If it was my boat, I'd keep what's there. It's dry and solid, you can skin it with more glass and even add another core layer which would significantly enhance the structure when you install the pod extension. Remember, you started with a project boat. If you wanted a completely new boat, you'd have started with a mold. :)
I removed all the coring in my transom, but it was an easy decision since the original was badly patched by a previous owner and largely mulch in many areas. If yours is sound, I'd be tempted to just build upon what is already there and solid.
Drill a few inspection holes and if the ply honestly looks in good condition then build off it. You will be opening a serious can of worms if you try to replace it. If it ain't broke don't fix it
Andy, if around the keyholes is good, lesve the core. Bertrsm thought the core was good enough why would not. Not withstanding the extra build need by Armstrong
I'd say if you're going to take the core out of that transom, just cut the whole back out. Yeah it means rebuilding most of the transom from nothing. But it also means you're done with the tear down in a day, and the heavy lifting part is construction, rather than grinding and tear down.
I understand wanting to have the peace of mind that it has been replaced with the coosa, but with the amount of work it will take to rip out a perfectly good transom, I think you should leave it. Take the time to make sure it’s sealed up perfectly and move on.
I take it that you thought it needed to be redone because it looked like a hack job? Rip it all out so you never have second thoughts that you are doing a re-hack job.
If the transom core is in good shape, keep it. However, I would enlarge all of the current drilled holes and fill with epoxy and redrill. This will help to ensure that any future water intrusion around the bolts for the outboard motor platform is protected from the wood core.
I've been watching you for a while now. And the one thing I noticed is you DON'T take shortcuts, nor do you put out shoddy work. Whatever you do will turn out better than factory. I for one, what you to keep it and get that boat out on Superior with your family. :)
This would be my preferred approach, as it removes the need to also strip the solid plywood core, allows you build a brand new transom and even potentially removes the need of a transom bracket!
@@AdrianoCisternino yep, that was my reasoning too. And one more thing, I really think it will be faster, inboard versus outboard needs a longer length.
Careful of project creep, if it ain't broke don't fix it. The whole "while I'm here I should...." results in a project you never get to enjoy, scab it all up to the same level then add a solid panel on top of that.
I used a lot of encapsulated exterior grade Fir plywood when I refit my sailboat. We tore it all apart for recycling last year and after twenty-seven year's on the ocean I didn't have a single area that water got into. My point being, and as you already know, properly done plywood is an excellent product for use on boats.
This isn't called "Outsiders Rule" Andy, in my mind I'd say what you know holds the majority vote, opinions are like butt O's, everyone has one, in the end, your Gut feeling and knowledge is Matter of Fact..My point of view carries no weight nor influence either way, stay true to thyself. Knowledge and experience makes it matter. Thumbs up, it will all work !!
Hi Andy, I voted to keep the plywood, but I do have a caveat to that vote. Rip that funky wood out of the old key holes. At that point you can make a couple of judicious cuts and assess how well the plywood is bonded around the key holes. If it is solid, then fill in the key holes and beef the rest of the transom up. If there is delamination, well you know what you have to do.
I've so been there on cutting where I shouldn't, not on a boat, though, on a piano soundboard (I'm a piano technician). Recovering from that actually gave me some skills that provided me a decent living over the years, but it sure as hell didn't seem like that at the time!! In terms of your poll, due what your patrons vote for. I'd be one if I could afford it... I've learned a lot, and really appreciate your instructive videos!
thank you for the non virus related content. also... Mas on sail life had the same decision to make regarding his rotted stringers on athena. he decided to simply reinforce in place with enough material to make the rotted cores a non-issue because quite simply it was the easiest path to a workable solution. i learn something valuable and new from each of your videos and though i would dearly love to see the process of removal and reinforcement, perhaps the best lesson learned here is, "if it aint broke don't fix it."
Pez Pengy I think Mads messed up by just glassing over the rotten beams. If just adding a few more layers of glass made it as strong as glass laminated over wood don’t you think the original designer would have just made the whole thing out of a few more layers of glass to start with. There is no way that Mads way is stronger than original glass over wood plank . He may regret it later. I hope not though.
@@mwatkins2464 Mads Athena stringer lay up was engineered to the hull weight, there is no way it is weaker than the original in original condition which relied on the wood core (which decomposed) as part of the stringer strength. Go back and watch how many layers it took before you say "few more layers" again so you transfer the info accurately.
Why would the original designer add that much more glass? It's waiste of time and money. Also, how accurate durability calculations were in 1985? If any analysis was made in the beginning. I think Mads had a finite element analysis made to assess his options with the stringers. His only possible problem with the rotten wood is the added smell to the boat.
@@mwatkins2464 In a beam most of the strength is in the outside. The middle is just there to keep the outside in the right place. An I beam is a good example. The two big flanges take the load and the middle web just keeps the flanges in the right place. Mads added a lot of glass on the outside so those beams are probably much stronger than the origainal setup. It wasn't done that way in the factory because it is difficult to glass over air to create a hollow structure. Also wood is a lot cheaper than glass.
Hi, why not use fr4 instead of the coosa? Can you go with a thinner fr4 vs coosa? Is there a large cost difference and what are the pros and cons of the choice of material properties on the stern? Great video. It seems cutting into the bottom was the right thing to do all things considered.
Considering the lengths you are going to restoring this boat why not just bite the bullet and tear it out and replace the entire transom with coosa...it would make for great content and keeping with the spirit of the build and as with most things you do, it would be of far greater quality than the original and should never be an area of concern again simply because coosa doesn't absorb water and should never rot...I know wood has been used for hundreds of years in boat building and with proper construction and care can last a lifetime...but since you have basically devoted thousands of hours and dollars to this build documenting every step why not leave behind something that truly is a legacy of sorts that with proper care may last several life times due mainly to the quality of work you are doing and the superior quality materials used... Thanks for all you do!!! I always look forward to seeing what you are doing next... always interesting and informative... Keep on keeping on brother!
Couldn't find the link to the poll. Everyone is going to say RIP out all wood and go with coosa .But seriously will the boat still be on the water 40 years now? Its solid wood ,you obviously know what you are doing, leave well enough alone and strengthen the top. Love your videos keep up the good work.
I think u should do the full coosa transom , for a few reasons. #1 more content for ur channel .I mean ur channel really help me with my 17ft boston super sport now it's perfect . #2 u wont have to ever redo it #3 it will be even stronger I mean the ocean is unpredictable and with ur family involved. Safety is no 1 priority. By the way love them bertram my dream boat.
Keep it and do your thing, it’s fine, like you said, it’s gonna last. I have no doubt whatsoever it will be perfect and strong enough to hold those monsters!!
Andy, I’ve been watching your videos for a long time and you are one of the best on “how to” instructor videos I’ve seen on UA-cam. My question is that why not go further in conducting an experiment to put your skills to the test. Why not discard the outboard bracket and run stringers through the transom and make an integral outboard bracket? Personally, if I had the time, which a lot of folks might have during this epidemic I’d rather do something that would last for a long time. You have the shop, the materials to do it and with some imagination it can be done.?
The commenters here are part of the "wood bad. coosa good" milleu and you shouldn't let yourself fall into that trap. If the wood is sealed, it's just fine.
peace of mind rip it out , and i'm ocd and would rather see perfection of all coosa board running from side to side rather than piecing it in sections at a time . down the road it'll be an easier sale if its over done.
Might as well rip it out... Your're a glass guy, that's what your good at, so get rid of the plywood. It really doesn't matter though, that boat will never see water again...it's never going to get finished at this pace. So what are we looking forward to. Next week you will cut out the transom. The week after that you will cut out and first the first layer of Coosa and install it. The week after that you lay up the next layer of Coosa. Then the next week you will glass it all in.... You really do need a few helpers and move this along. This old boat is killing your youtube channel. BTW that connector that you ripped out was the thrust brace. It connected the transom to the actual thrust beam that the engine pushed against.
Ok, after seeing where you are... I’d cut it all out. I would replace with the komerling product I told you about though instead of coosa. I’d do 4 @3/4” layers top to bottom with two knees between the bolt holes for the bracket at around 36” apart or where ever they can be tied to the stringers. My email is jecurry07@yahoo if you would like more info on the komerling product. I’m not a rep or salesman but have used all the cores available on the market today and feel it is a better product for this application. And, it’s only about $130 per 4x8 3/4” sheet, James!
If you are confident the wood is sealed, I would leave the plywood. since the bolts leaked... do you really think the wood is sealed? That is the real question here. Keep up the good work!
Andy I’m on the fence on what I would do, if the boat is going to sit in the water during the boating season 24/7 where it has more of a chance to develop leaks, I might consider replacing the plywood, if the boat is going to be trailered to and from the lake, I would probably leave it, just my thoughts 👍😁
HAVING OWNED ONE OF THESE UNITS, I KNOW HOW STRONG THAT RANSOM IS, 400 PLUS HORSE HOLMAN MOODY SETUP HELD WELL , BOAT WAS DROPPED WHILE BEING LIFTED, HAD TRANSOM AND KEEL X RAYED NO PROBLEM. ADDING THICKNESS WILL STRENGTHEN THE ALREADY STRONG TRANSOM.
I for one would like to see you fix the transom as is. Your work is stellar, and I believe it would be more realistic for us viewers to see you repair from the solid " leftovers" you have now. Love your work and channel !
After watching the video, reading the replies and incorporating my experience as limited as it may be. Your there, hands on ... If the core is absolutely solid and your confident you can seal the finished product -if anyone can, you can- just go ahead a build up. But if anything in your being questions that rebuild, give in to your ocd and rip it all out. I feel certain"YOU" can do a great job either way you go but in the end ... Will you have confidence in the transom work to take out family and friends? Personally, if the core is solid and I know my work and effort will result in a better structure that will last 20 or 30 years minimum. Build it up!!! You already have it down to the original Hull and if that is good then why go through the added time and expense. Find out the specs for the Armstrong bracket and meet or exceed it. I look forward to seeing which way you go and the final product. As always, great work on everything to do.
Keep what’s there , build off of that . Be extra vigilant on sealing it up when you reinstall all the hardware. Coat every hole that has to go through the transom liberally with an epoxy or some other waterproofing that will soak in thoroughly inside the holes . 👍👍😊
No chance like the present one to replace. Much much easier now to go all the way. That said, a looooot more time and effort whereas you could just reinforce what is there and be 99% confident that it will be fine.
Never saw a transom that didn't have water around the drain plug. I would have to put at least a larger layer of wood over the outdrive holes so all the joints don't fall on the same spot. How does the outside glass look around those holes?
"Given that it's a weak area" l would ask Bertram if they have an approved schedule? I've been with you for awhile now, and this is your own boat so l know you won't be taking any short cuts. Has this modification been done before, as with any vehicle in a fluid, move the engines will have an effect on buoyancy, and center of gravity. Have any calculations been made? I suspect that the outboard mounting bracket is calculated to offset the this, might be a good idea to double check? Love your channel it would make a good video to show the weight and balance much and center of gravity or vertical center of buoyancy. I put a much heavier engine on a homebuilt (successfully) to avoid drag inducing ballast in the tail moved the engine back about 6" to compensate. 👍👍👍👍 I expect you've already got those bases covered. For the amount of work already done, l'd put a router on a 18" X 12" clear Pespex/Lexan base and rout out as much of the ply as possible before resorting to hand tools (l suppose a Festool multicut with the depth stop or a shop rigged depth stop would be helpful) and replace with non-rotting water permeable ply. Just on the grounds l wouldn't want to be revisiting it again after all the strengthening has gone over it. 😭😭😭 Excellent work and l am sure however you tackle the troublesome transom will be a well thought out and practical solution. 👍👍👍👍👍👍👍👍👍 It it was a drunken sailor l'd put him in the scuppers with a hose pipe on him🤭 Addendum Say the original engine was 500lbs and the center of that mass 30" inboard of the transom, and a 25' boat is level in the water. (25 X 12 - 30) X 500 = 135,000 lb inches for equilibrium (floats level) (25 X 12 + 30) X 800 = 264,000 lbs inches Or Close on nearly double. Very approx equivalent to putting a 1000 lbs heaver inboard, yeap not sure how much effect that would have, interesting stuff 🤔👍🤣 (check my Math could be wrong guessed wait of original engine and arm length ) probably not a biggy l thinking its like 4 big blokes moving from midships to standing on the transom.
BTW the leaking bolt is a red herring, there was no water leaking OUT Between the Armstrong mount and the transom. Only has to be water tight on that joint, that bolt is INSIDE the water tight compartment. Andy your good 👍👍👍👍👍👍👍
🎶What do you do with a leaky transom? What do you do with a leaky transom? What do you do with a leaky transom? Early in the morning. Whack it on the side with a great big hammer, Whack it on the side with a great big hammer, Whack it on the side with a great big hammer, Early in the morning. 🎶
Not cheap, but an easier super sturdy permanent solution is to bond on a 1/4-1/2" thick aluminum plate. Drill a few 1" holes to help bond THROUGH the plate to the backing fiberglass. Any bolts that need to go through the transom could be sleeved with PVC to eliminate even t a remote change of electrolytic galvanization transferring in to the aluminum plate. The plate will cost $225-250 and will give absolute piece of mind.
Leave it, if you feel good about the core,,you are getting into design/engineering areas,,crazy as it sounds, call one of the bass boat company and have a conversation about their layup "schedules". they are currently designing for 400 hp with short transoms and jack-plates... their opinion would have a very high Value...either way,,,thinking it will go 30 years,,,unless you plan to race this puppy Offshore..
Xylene / Xylol is common solvent used in cleaners and is at times even used as thinner of paints (when wanting it to take longer to dry vs typical paint thinners that has quicker flash point). 5200 on the other hand uses Glycol (Diethylene Glycol Monoethyl Ether), likely to help it bond with polyester resins and polyurethanes since glycol is typically used in those as well. So in theory a Glycol solvent would work best at breaking down 5200 ... but it would also do the same to the polyester resin which you are not wanting to do. Acetone and MEK (Methyl Ethyl Ketone) as I am sure you know are used in marine industry to remove 5200, and they do work well. However, specific products like Marine Formula Debond, Anti-Bond and similar product Goo Gone has tested to work easier allegedly. I never have tried them, just use MEK which works ok. And MEK is easier to get and likely cheaper then those other special products, which again may work better but MEK works good enough than to go to all that hassle of finding and paying more. But this makes me wonder if one my old personal fav solvents of Lacquer Thinner would work as well, since it is basically just MEK, Toluene and Naptha. Strong stuff though, so only use it when its needed.
Assuming the existing plywood is completely dry seems like an assumption most boat people would make. However, boat people, myself included, are extremely optimistic, otherwise, we'd never leave the dock. Err on the side of caution.
I own a 1966, V26 Stamas, originally a single Chrysler Dana Drive I/O, that I repowered with a twin outboard bracket & 200 HP outboards. The transom was well sealed in fiberglass at the factory, there was no water intrusion, and the plywood core was as solid and hard as when the boat was built. That's over 50 years. If the original construction is good, and no water has penetrated, there's no reason to replace the plywood core. Reinforcing for the bracket loads is the bigger issue. Greg
I work for a boatyard and have installed many armstrong brackets, and even have one on my own boat. Standard transom thickness is about 2". Two 3/4 sheets of plywood or coosa laminated together, and outside skin of 3/16 to 1/4 and an inside skin of about an 1/8. In good condition that will support a bracket and twin 130's no problem. The Bertram 25 was initially designed for inboards only and only has a small section of traditionally cored transom. That bump-out area. Should be two layers of 3/4 plywood in there. The rest of the transom is solid glass but thin, as you discovered. I'd leave the existing plywood core, redo the keyholes, and laminate two layers of 3/4 coosa over the entire inside of the transom, using filler or oddball pieces to bring all the levels up. I would then also build some coosa knees to tie the transom to the top of every stringer. On my 1979 23 seacraft I installed an armstrong bracket on, I did three knees. One to each of the tops of the large box stringers, and another to the center stringer. I would also remove the bracket from the transom and grind off the bottom paint and re-bed the bracket to the hull NOT to the top coat of the existing bottom paint, which is how it looks. With the bracket off you could also dig out the transom core from around every bracket bolt hole and fill with thickened epoxy and re-drill. Then the core would be truly sealed and you would have nice solid chunks of epoxy in the transom to tighten the bolts to. Just my .02 cents USD. Loving your videos, as I do a lot of systems and structrual work, but am just getting into the refinishing aspect of boat work. Learning a lot from you about gelcoat and paintwork. Keep up the good work!
Build it out & roll with it. In 35-40yrs you won’t be worried about boats at that time! Go get it done & enjoy it, summer time is around the corner. While we are all still here, go enjoy as you much as possible. Stay safe & keep the good videos rolling! 🍻⛵️
Ok, I'm not a boat builder... But, if yo build up the top and sides to match the center section with whatever you would normally use... Then cut a 1" thick piece of (I'm going to say plywood. You probably know better material) to cover the entire transom and bond it all together and transfer the load across the whole area would that accomplish what you trying to reinforce... Like I said... Don't claim to be a boat builder.
Option 3: Park the Bertram in your front yard, fill it with dirt and plant flowers in it. Then, buy a brand new boat and start making videos of you wrecking people holding a rope behind it! BAHAHAHA!!
My question to you is gonna be!!! Whats gonna give YOU the GREATEST peace of mind! what is gonna be the strongest, as others have said if it aint broke dont fix it! but if this is gonna be for you and your family, then you have to do what you believe is gonna be best. I would build up the low area and then finish the whole area with the coosa like you described. Take care and be safe.
Why the dewaxer worked is not because of the xylene necessarily, but the fact the surface of the old glass was not properly prepared for the G10 and 5200 that was added on top. The wax on the surface of the glass then was broken down by the xylene and BAMM! No more bond and it peels off fairly easily. I have used 5200 and wiped the top off it down with xylene and not had it deteriorate.
A tip for removing the Armstrong bracket; support the bracket with your hoist then use a long piece of 80lb mono or braided fishing line, tie some sticks around the ends and wrap it around the joint and saw trough the 5200 like butter. When you remount the bracket leave a new rip cord for the next guy before you use your 5200 or boat works similar. Looks Good, Bill W
Two words: reciprocating saw. I know the old core is fine... now. But it doesn’t seem like any greater level of effort to replace the existing vs. building up the existing. The only difference seems to be the demo, which is the fastest & easiest part. Once the demo is done, you’ll have larger pieces of solid Coosa which will likely outlast all of us. My $0.02.
Rip it out!. If you are going to build up the top part anyway, it can be quite easy, too: Take the platform off and cut out the thick part of the transom completely. Then you can use the remaining top part as the guide to fit in the lower plate of Coosa all the way from the top to the bottom and put the wider covering plate of Coosa from the inside over the whole width of the transom as planned. All you have to do then is glass the transom from the outside, but that should be a no-brainer for you as you will have the new Coosa core to build up against. Glass up and finish the rest, remount the platform - job done! Refitting the whole rest of the boat with Coosa and fiddling around with two different materials in the core, of all places at this part of the boat where you have the highest loads and stress for the material, is, imho a false compromise. Taking this radical solution will give you a rock solid foundation for refitting the platform, and it's risk free as far as moisture is concerned. You are doing such a great job with the rest, paying so much attention to detail - to my mind you shouldn't fall short here. No second guessing with peace of mind! Love our channel! Done some binge-watching as I am bound to refit my 1974 Lanaverre 590 - a small French daysailer. I feel so inspired by your channel, thanks! Greetings from Hamburg, Germany, Mark
As far as the transom per se, I doubt it matters structurally which method you choose. I'm confident you can do either correctly or make it look fantastic. Consider doing whatever is less time consuming. Now that the dead and live live loads (especially thrust) you've added to the transom by using outboards will be adequately supported by the transom, the concern is to ensure that the these loads will be transmitted to the stringer system and hull bottom/sides adequately to prevent over stressing the stringer/hull frame (racking and flexing). Great project Andy. Love the series.
1970’s/80’s technology and engineering isn’t as good as today’s. Cosa is a far superior product. I think you know this and is why your really thinking about doing this. It’s a lot of extra work but in the long run you know you’ll have piece of mind.
You are replacing the plywood with Coosa .That was your original plan for the entire boat. Don't wimp out now. I would like to see the process. Is that not why your channel exists ... Process and Procedures not turning out quick jobs for customers
Leave it there and build up on it... too many hours in labor going the other way and that is if no mistakes are made...do not create more work for yourself than you have to....Bring Out Another Thousand....Good Luck!
I'm no boat builder or engineer or anything... So take my opinion with a grain of salt. If it's going to cost more (i.e. time and effort) to rip out the old transom, than say- to add material for the thickness required, I'd say just leave the old transom in. As you said, you feel it's still a viable transom. But, I can see your point with ripping out everything and starting fresh. There's the rub I guess- which decision will end up being easier and less costly in the end? Hmmmm... Quite the conundrum.
Andy, don't spend all that time and headache ripping out the plywood. Since the plywood is dry then it will be fine like you say for 20-30 years, it makes no sense to remove it. I'd say just thicken it up with the new foam boards, enlarge the holes and fill them with epoxy and re-drill them to the original size so the plywood stays fully sealed. It will be more than strong enough. Love the attention you give to these projects, really great workmanship !
A pair off Suzuki 350 HP motors weigh at least 660 kg plus all fittings ect. Other brands similar .And weight in a totally different place to inboards. Where engine is carried on the bottom . replace whole transom or you won't get insurance or peace of mind
Talk about digging in :P too bad you don't have a pair of I/O's at this point. Building up probably less $$$ in materials, all new more $$$ in materials. All the odd cutting to build it up, or all fresh with layups and what not might be close time wise.
Xylene is a VERY typical solvent for all kinds of things. Go buy a gallon at the usual scumbags and use that instead of that expensive total boat stuff. I agree using the Cleaner/Dewaxer for what it is intended for, but for what you are doing...yea, go get a gallon of Xylene instead.
I heard ya start to quote Ave at 13.55... nice. I would think sanding, layering another core and glassing it all in wouldn't be a bad thing. If the core isn't damaged, let it be. It was made right and sealed properly.
Do you have, or could you make, a video on the different materials you use and the tools as well. What they all do and how they're used? Kind of a fiberglass 101. You're the best fiberglass teacher on UA-cam
I would build off of the core you have NOT!!! I changed my mind because the repair done by someone else was not done right the other repair may be the same. So I would have to rip it all out so I know it’s strength and that it’s sealed properly. Take it down to the outer skin then start building it stronger. Thanks Andy 👍👍💰
What would be the most efficient way? What would be the most satisfying way. If building over will work and your happy with it, go that route. If blowing it out would help you sleep better, go that route. Myself, sleeping better is always the better route in the end. Even if it seems unnecessary.
With the amount of horse power and weight and torque that will be applied to the back of the boat. Basically a fully loaded ( or possibly over loaded boat 6 fat dudes drinking) gear and such. Hammering down on the throttles ( we don't all ease off the docks). 1/4 inch fiber glass? really? honestly Chainsaw the back off. glass in a new transom. be faster then trying to match up and fill in the cracks. Your work is most excellent but as you know each join is a potential "leak/weep" point and the amount of fairing oh la laaa. Yes that seems a bit extreme. As my father would say. The best path is not always the most easiest. by moving the motors that far back. your going to be basically lifting the entire boat by the transom. then add chop of water bouncing the boat up and down. I fear that your going to put undue force on it and unless it has a VERY stable and secure transom. your going to have many "stress cracks" and later water intrusion and delamaination issues. I mainly work on old slow sail boats and I am often surprised by the amount of stress those boats and their hulls are under.
Andy the Hull was built for inboards not twin outboards on a bracket. If you just had the outer skin right now, how would you build the inside of the transom up to your desired thickness? 3" of coosa and a thick well laid up inner skin with offset tabbing or various thicknesses of plywood and glass, and some pine for the keyholes? I'm sure you could find out what Bertram would recommend or get the opinion of a naval architect or engineer. Maybe not a situation for "well it lasted this long it should be good." Lake Superior is cold and deep even in the summer.
Hi Andy Great comments Everyone both for keeping it fixing up the old to handle the new outboards or completely removing the old and in with the new. For me and my blue collar money and time I would fix it as is and get my family out in the water before they go to college my boys are six and eight but if money and time is not your issue and you just called your Ranch manger to have him rotate you Polo Ponies for this weekends Match then by all means replace all the old wood and replace the entire and stretch it to 31 foot because everyone know that the 31by10 Bertram is the woulds best hull and reinforce it to handle Four 350hp V8 Merc racing motors and blow by the Yacht Cub at a hundred and twenty Bata Bing Bata Boom.
I have never seen a plywood core that didn't saturate. Your boat maybe was stored out of the water most of its life? Through fasteners leak and are a point of entry for water and it would seem no matter how well they are sealed and bedded. And there is always something that has to be mounted, the newest latest and greatest, trolling motor brackets, tow eyes, trim tabs, etc. etc. also inside brackets for pumps down in the bilge and a myriad of other things will allow egress of moisture over time. In more than sixty years of working around boats this is the way it is. Case in point those Armstrong mounting bolts looked like they had a good amount of 5200 sealing them yet you found the leaks seaping in through the entire thickness of the transom. Who knows how much just entered and was absorbed at the plywood? As has been proven with fiberglass 'blisters' fiberglass is not impermeable to water. The more draft the more pressure forcing the water into the glass. Even the new 'barrier' coats are not given with a 100% guarantee over time. You are close enough now is the time to get it out. It will never be easier. The coefficient of expansion on metals and fiberglass is also going to contribute to breaking any watertight bond pretty quickly with your hot summers and super cold winters. Nope I would take it out. Several good techniques on doing that which make it pretty quick. Boatworks Today down in Florida did a series on a very similar boat and transom repair covering it. Several others have tackled the job. Comes out in pretty large chunks. Where it is saturated it quite literally falls out once the fiberglass is removed. When rebuilding the transom set in solid epoxy (check Gougin Bros printed material on how) in areas where you are going to have bolts to prevent compression (another cause of leaking). Now you can rest assured it will last a lifetime. Take care. Doug
Leave the plywood. While Coosa doesn't rot it is only marginally better than plywood when the core gets wet. Any water intrusion combined with action of the fiberglass will create internal hydraulic pressures that will create delamination of the Coosa. Their is no perfect core. JJ
Repair keyholes, add an inch more to the overall thickness of the transom, then add a glassed in strong-back just above keyhole height across the transom and forward on each side 18" or so.......
Despite the backyard job done to try and stiffen up the transom, the original core is still in good nick even with all the bolt holes drilled through it. For me, I'd keep the original core and anywhere you have to drill through the transom, overdrill the holes, backfill with thickened epoxy and then drill (when fully cured of course) to the final required size. The good old..."drill, fill, drill" technique. I would do the the backfilling before you proceed with the additional Coosa stiffening then do the final drill after the stiffening work is done. In my mind, doing it this way it will give you peace of mind that you have completely sealed off the interrnal ply core from the elements. A whole lot easier than spending day after day after day trying to remove a perfectly good core.
Either all ply or all coosa. As long as the existing ply is dry, I don't see where you can go wrong either way. But If you leave the ply there's no reason to use coosa for your work. Oh and for removing ply coring get an aggressive wood carving burr for your 4.5" grinder. Once I get the glass off, I can have the core cleaned out in no time. Guards from going too deep with saw too. While it will remove glass it's dramatically slower than wood so you get the benefit of fast wood removal and the safety of being able to hit the glass without doing immediate damage. Just make sure you don't loose control of the tool, it removes skin just as fast, guess how I know. www.woodcraft.com/products/kutzall-extreme-dish-wheel-4-1-2-diameter-very-coarse-dw412x120?via=573621bd69702d0676000002%2C573621da69702d0676000d03%2C5763fe9869702d6582000b71
If it was my boat, I'd keep what's there. It's dry and solid, you can skin it with more glass and even add another core layer which would significantly enhance the structure when you install the pod extension. Remember, you started with a project boat. If you wanted a completely new boat, you'd have started with a mold. :)
I removed all the coring in my transom, but it was an easy decision since the original was badly patched by a previous owner and largely mulch in many areas. If yours is sound, I'd be tempted to just build upon what is already there and solid.
Leave it baby!
Drill a few inspection holes and if the ply honestly looks in good condition then build off it. You will be opening a serious can of worms if you try to replace it. If it ain't broke don't fix it
rip it out wont have to wonder, your banking that whats in side is good you came this far, that patch work on port side might also be ?
Andy, if around the keyholes is good, lesve the core. Bertrsm thought the core was good enough why would not. Not withstanding the extra build need by Armstrong
I'd say if you're going to take the core out of that transom, just cut the whole back out. Yeah it means rebuilding most of the transom from nothing. But it also means you're done with the tear down in a day, and the heavy lifting part is construction, rather than grinding and tear down.
I understand wanting to have the peace of mind that it has been replaced with the coosa, but with the amount of work it will take to rip out a perfectly good transom, I think you should leave it. Take the time to make sure it’s sealed up perfectly and move on.
I take it that you thought it needed to be redone because it looked like a hack job? Rip it all out so you never have second thoughts that you are doing a re-hack job.
Open the keys holes for further examination. If everything is fine then repair key holes and add crisscross pattern of acoosa to build transom.
Does Coosa have "grain?" Would he end up with better strength going crosswise than he would with overlapping laminations?
I know little to nothing so bare with me, I do believe Coosa board is bidirectional.
I'd like to see you get out on the water this year.
Mars Rover it’s illegal right now in south Florida.
May just be me, but if the current setup is dry and solid I’d reinforce it an be done with it.
If the transom core is in good shape, keep it. However, I would enlarge all of the current drilled holes and fill with epoxy and redrill. This will help to ensure that any future water intrusion around the bolts for the outboard motor platform is protected from the wood core.
I think if you're gonna fill the key holes with glass you should just redo the whole thing and make it all a solid piece of coosa.
I've been watching you for a while now. And the one thing I noticed is you DON'T take shortcuts, nor do you put out shoddy work. Whatever you do will turn out better than factory. I for one, what you to keep it and get that boat out on Superior with your family. :)
Right, bold suggestion, lengthen the boat and incorporate the mounting for the engines.
This would be my preferred approach, as it removes the need to also strip the solid plywood core, allows you build a brand new transom and even potentially removes the need of a transom bracket!
@@AdrianoCisternino yep, that was my reasoning too. And one more thing, I really think it will be faster, inboard versus outboard needs a longer length.
Careful of project creep, if it ain't broke don't fix it. The whole "while I'm here I should...." results in a project you never get to enjoy, scab it all up to the same level then add a solid panel on top of that.
would love to see how to replace a wood transom with coosa and if the wood goes bad, then you'll need to remove the coosa and the wood
noli novio look up born again boating on UA-cam he’s done a refit with coosa
I used a lot of encapsulated exterior grade Fir plywood when I refit my sailboat. We tore it all apart for recycling last year and after twenty-seven year's on the ocean I didn't have a single area that water got into. My point being, and as you already know, properly done plywood is an excellent product for use on boats.
This isn't called "Outsiders Rule" Andy, in my mind I'd say what you know holds the majority vote, opinions are like butt O's, everyone has one, in the end, your Gut feeling and knowledge is Matter of Fact..My point of view carries no weight nor influence either way, stay true to thyself. Knowledge and experience makes it matter. Thumbs up, it will all work !!
Hi Andy, I voted to keep the plywood, but I do have a caveat to that vote. Rip that funky wood out of the old key holes. At that point you can make a couple of judicious cuts and assess how well the plywood is bonded around the key holes. If it is solid, then fill in the key holes and beef the rest of the transom up. If there is delamination, well you know what you have to do.
I've so been there on cutting where I shouldn't, not on a boat, though, on a piano soundboard (I'm a piano technician). Recovering from that actually gave me some skills that provided me a decent living over the years, but it sure as hell didn't seem like that at the time!! In terms of your poll, due what your patrons vote for. I'd be one if I could afford it... I've learned a lot, and really appreciate your instructive videos!
thank you for the non virus related content. also...
Mas on sail life had the same decision to make regarding his rotted stringers on athena. he decided to simply reinforce in place with enough material to make the rotted cores a non-issue because quite simply it was the easiest path to a workable solution. i learn something valuable and new from each of your videos and though i would dearly love to see the process of removal and reinforcement, perhaps the best lesson learned here is, "if it aint broke don't fix it."
Pez Pengy I think Mads messed up by just glassing over the rotten beams. If just adding a few more layers of glass made it as strong as glass laminated over wood don’t you think the original designer would have just made the whole thing out of a few more layers of glass to start with. There is no way that Mads way is stronger than original glass over wood plank . He may regret it later. I hope not though.
@@mwatkins2464 Mads Athena stringer lay up was engineered to the hull weight, there is no way it is weaker than the original in original condition which relied on the wood core (which decomposed) as part of the stringer strength. Go back and watch how many layers it took before you say "few more layers" again so you transfer the info accurately.
Why would the original designer add that much more glass? It's waiste of time and money. Also, how accurate durability calculations were in 1985? If any analysis was made in the beginning.
I think Mads had a finite element analysis made to assess his options with the stringers. His only possible problem with the rotten wood is the added smell to the boat.
@@mwatkins2464 In a beam most of the strength is in the outside. The middle is just there to keep the outside in the right place. An I beam is a good example. The two big flanges take the load and the middle web just keeps the flanges in the right place. Mads added a lot of glass on the outside so those beams are probably much stronger than the origainal setup. It wasn't done that way in the factory because it is difficult to glass over air to create a hollow structure. Also wood is a lot cheaper than glass.
Hi, why not use fr4 instead of the coosa? Can you go with a thinner fr4 vs coosa? Is there a large cost difference and what are the pros and cons of the choice of material properties on the stern? Great video. It seems cutting into the bottom was the right thing to do all things considered.
Considering the lengths you are going to restoring this boat why not just bite the bullet and tear it out and replace the entire transom with coosa...it would make for great content and keeping with the spirit of the build and as with most things you do, it would be of far greater quality than the original and should never be an area of concern again simply because coosa doesn't absorb water and should never rot...I know wood has been used for hundreds of years in boat building and with proper construction and care can last a lifetime...but since you have basically devoted thousands of hours and dollars to this build documenting every step why not leave behind something that truly is a legacy of sorts that with proper care may last several life times due mainly to the quality of work you are doing and the superior quality materials used... Thanks for all you do!!! I always look forward to seeing what you are doing next... always interesting and informative... Keep on keeping on brother!
Couldn't find the link to the poll. Everyone is going to say RIP out all wood and go with coosa .But seriously will the boat still be on the water 40 years now? Its solid wood ,you obviously know what you are doing, leave well enough alone and strengthen the top. Love your videos keep up the good work.
I think u should do the full coosa transom , for a few reasons. #1 more content for ur channel .I mean ur channel really help me with my 17ft boston super sport now it's perfect . #2 u wont have to ever redo it #3 it will be even stronger I mean the ocean is unpredictable and with ur family involved. Safety is no 1 priority. By the way love them bertram my dream boat.
Rip it out remove all doubt, I’m watching your doing....ya have to build it up anyway!
Rip it out so you wont be secong guessing yourself , especially if something happenes later down the road.
Meatbaltn, looks like were a minority here but I concur
I for one want to see Her splash :) He's been second guessing the transom for for quite some time now.
The safety of your family and your self should never be at risk, it is a safety issue that is why he should do the transom
If I am keeping the boat for myself. Take out the potenial weak link. If I am selling it. Nothing wrong with it. So my conscience will be clear.
Good work. Scary how bodgers can wreck a boat. Make it like new, those big outboards will really add stress it wasn't meant to take.
Keep it and do your thing, it’s fine, like you said, it’s gonna last. I have no doubt whatsoever it will be perfect and strong enough to hold those monsters!!
Perfect time too install a couple of Volvo out drives, don’t be a cheapskate ::)
Andy, I’ve been watching your videos for a long time and you are one of the best on “how to” instructor videos I’ve seen on UA-cam. My question is that why not go further in conducting an experiment to put your skills to the test. Why not discard the outboard bracket and run stringers through the transom and make an integral outboard bracket? Personally, if I had the time, which a lot of folks might have during this epidemic I’d rather do something that would last for a long time. You have the shop, the materials to do it and with some imagination it can be done.?
Are you in touch with the designer of this hull?
The commenters here are part of the "wood bad. coosa good" milleu and you shouldn't let yourself fall into that trap. If the wood is sealed, it's just fine.
peace of mind rip it out , and i'm ocd and would rather see perfection of all coosa board running from side to side rather than piecing it in sections at a time . down the road it'll be an easier sale if its over done.
Might as well rip it out... Your're a glass guy, that's what your good at, so get rid of the plywood. It really doesn't matter though, that boat will never see water again...it's never going to get finished at this pace.
So what are we looking forward to. Next week you will cut out the transom. The week after that you will cut out and first the first layer of Coosa and install it. The week after that you lay up the next layer of Coosa. Then the next week you will glass it all in.... You really do need a few helpers and move this along. This old boat is killing your youtube channel.
BTW that connector that you ripped out was the thrust brace. It connected the transom to the actual thrust beam that the engine pushed against.
Ok, after seeing where you are... I’d cut it all out. I would replace with the komerling product I told you about though instead of coosa. I’d do 4 @3/4” layers top to bottom with two knees between the bolt holes for the bracket at around 36” apart or where ever they can be tied to the stringers. My email is jecurry07@yahoo if you would like more info on the komerling product. I’m not a rep or salesman but have used all the cores available on the market today and feel it is a better product for this application. And, it’s only about $130 per 4x8 3/4” sheet, James!
If you are confident the wood is sealed, I would leave the plywood.
since the bolts leaked... do you really think the wood is sealed? That is the real question here.
Keep up the good work!
Andy I’m on the fence on what I would do, if the boat is going to sit in the water during the boating season 24/7 where it has more of a chance to develop leaks, I might consider replacing the plywood, if the boat is going to be trailered to and from the lake, I would probably leave it, just my thoughts 👍😁
HAVING OWNED ONE OF THESE UNITS, I KNOW HOW STRONG THAT RANSOM IS, 400 PLUS HORSE HOLMAN MOODY SETUP HELD WELL , BOAT WAS DROPPED WHILE BEING LIFTED, HAD TRANSOM AND KEEL X RAYED NO PROBLEM. ADDING THICKNESS WILL STRENGTHEN THE ALREADY STRONG TRANSOM.
I'd replace it. That way to know 100% for sure its solid and stays that way.
I for one would like to see you fix the transom as is. Your work is stellar, and I believe it would be more realistic for us viewers to see you repair from the solid " leftovers" you have now. Love your work and channel !
After watching the video, reading the replies and incorporating my experience as limited as it may be. Your there, hands on ... If the core is absolutely solid and your confident you can seal the finished product -if anyone can, you can- just go ahead a build up. But if anything in your being questions that rebuild, give in to your ocd and rip it all out.
I feel certain"YOU" can do a great job either way you go but in the end ... Will you have confidence in the transom work to take out family and friends?
Personally, if the core is solid and I know my work and effort will result in a better structure that will last 20 or 30 years minimum. Build it up!!! You already have it down to the original Hull and if that is good then why go through the added time and expense. Find out the specs for the Armstrong bracket and meet or exceed it.
I look forward to seeing which way you go and the final product. As always, great work on everything to do.
Seeing you now have screws going through it i would atleast replace where all the mounting bolts go and below them
Keep what’s there , build off of that . Be extra vigilant on sealing it up when you reinstall all the hardware. Coat every hole that has to go through the transom liberally with an epoxy or some other waterproofing that will soak in thoroughly inside the holes . 👍👍😊
Drill fill drill
I’d build off the existing platform being its new and dry . I tore a shabbily installed mako transom out that lasted 40 years .
Don't fix what isn't broke!!!!!!!! Spend that time, energy, effort and money else where!!!! I wanna see it float!
No chance like the present one to replace. Much much easier now to go all the way. That said, a looooot more time and effort whereas you could just reinforce what is there and be 99% confident that it will be fine.
Compressive Strenght of Coosa? Will it handle the crush of the bolts? Maybe a Backer?
Go all the way up for future equipment mounting! Just build off it.
Your videos are way too short!!! Check other UA-camrs....they have nice long interesting videos
Never saw a transom that didn't have water around the drain plug.
I would have to put at least a larger layer of wood over the outdrive holes so all the joints don't fall on the same spot. How does the outside glass look around those holes?
"Given that it's a weak area" l would ask Bertram if they have an approved schedule?
I've been with you for awhile now, and this is your own boat so l know you won't be taking any short cuts.
Has this modification been done before, as with any vehicle in a fluid, move the engines will have an effect on buoyancy, and center of gravity. Have any calculations been made? I suspect that the outboard mounting bracket is calculated to offset the this, might be a good idea to double check? Love your channel it would make a good video to show the weight and balance much and center of gravity or vertical center of buoyancy. I put a much heavier engine on a homebuilt (successfully) to avoid drag inducing ballast in the tail moved the engine back about 6" to compensate. 👍👍👍👍 I expect you've already got those bases covered.
For the amount of work already done, l'd put a router on a 18" X 12" clear Pespex/Lexan base and rout out as much of the ply as possible before resorting to hand tools (l suppose a Festool multicut with the depth stop or a shop rigged depth stop would be helpful) and replace with non-rotting water permeable ply. Just on the grounds l wouldn't want to be revisiting it again after all the strengthening has gone over it. 😭😭😭
Excellent work and l am sure however you tackle the troublesome transom will be a well thought out and practical solution.
👍👍👍👍👍👍👍👍👍 It it was a drunken sailor l'd put him in the scuppers with a hose pipe on him🤭
Addendum
Say the original engine was 500lbs and the center of that mass 30" inboard of the transom, and a 25' boat is level in the water.
(25 X 12 - 30) X 500 = 135,000 lb inches for equilibrium (floats level)
(25 X 12 + 30) X 800 = 264,000 lbs inches
Or Close on nearly double. Very approx equivalent to putting a 1000 lbs heaver inboard, yeap not sure how much effect that would have, interesting stuff 🤔👍🤣 (check my Math could be wrong guessed wait of original engine and arm length ) probably not a biggy l thinking its like 4 big blokes moving from midships to standing on the transom.
BTW the leaking bolt is a red herring, there was no water leaking OUT Between the Armstrong mount and the transom.
Only has to be water tight on that joint, that bolt is INSIDE the water tight compartment. Andy your good 👍👍👍👍👍👍👍
🎶What do you do with a leaky transom?
What do you do with a leaky transom?
What do you do with a leaky transom?
Early in the morning.
Whack it on the side with a great big hammer,
Whack it on the side with a great big hammer,
Whack it on the side with a great big hammer,
Early in the morning. 🎶
Total Boat Dewaxer and Surface Prep (according to their SDS) is 6% Xylene, 36% Ispropol Alchahol and 60% Naptha
Not cheap, but an easier super sturdy permanent solution is to bond on a 1/4-1/2" thick aluminum plate. Drill a few 1" holes to help bond THROUGH the plate to the backing fiberglass. Any bolts that need to go through the transom could be sleeved with PVC to eliminate even t a remote change of electrolytic galvanization transferring in to the aluminum plate. The plate will cost $225-250 and will give absolute piece of mind.
Leave it, if you feel good about the core,,you are getting into design/engineering areas,,crazy as it sounds, call one of the bass boat company and have a conversation about their layup "schedules". they are currently designing for 400 hp with short transoms and jack-plates... their opinion would have a very high Value...either way,,,thinking it will go 30 years,,,unless you plan to race this puppy Offshore..
Xylene / Xylol is common solvent used in cleaners and is at times even used as thinner of paints (when wanting it to take longer to dry vs typical paint thinners that has quicker flash point). 5200 on the other hand uses Glycol (Diethylene Glycol Monoethyl Ether), likely to help it bond with polyester resins and polyurethanes since glycol is typically used in those as well. So in theory a Glycol solvent would work best at breaking down 5200 ... but it would also do the same to the polyester resin which you are not wanting to do. Acetone and MEK (Methyl Ethyl Ketone) as I am sure you know are used in marine industry to remove 5200, and they do work well. However, specific products like Marine Formula Debond, Anti-Bond and similar product Goo Gone has tested to work easier allegedly. I never have tried them, just use MEK which works ok. And MEK is easier to get and likely cheaper then those other special products, which again may work better but MEK works good enough than to go to all that hassle of finding and paying more. But this makes me wonder if one my old personal fav solvents of Lacquer Thinner would work as well, since it is basically just MEK, Toluene and Naptha. Strong stuff though, so only use it when its needed.
Assuming the existing plywood is completely dry seems like an assumption most boat people would make. However, boat people, myself included, are extremely optimistic, otherwise, we'd never leave the dock. Err on the side of caution.
I own a 1966, V26 Stamas, originally a single Chrysler Dana Drive I/O, that I repowered with a twin outboard bracket & 200 HP outboards. The transom was well sealed in fiberglass at the factory, there was no water intrusion, and the plywood core was as solid and hard as when the boat was built. That's over 50 years. If the original construction is good, and no water has penetrated, there's no reason to replace the plywood core. Reinforcing for the bracket loads is the bigger issue. Greg
I work for a boatyard and have installed many armstrong brackets, and even have one on my own boat.
Standard transom thickness is about 2". Two 3/4 sheets of plywood or coosa laminated together, and outside skin of 3/16 to 1/4 and an inside skin of about an 1/8. In good condition that will support a bracket and twin 130's no problem.
The Bertram 25 was initially designed for inboards only and only has a small section of traditionally cored transom. That bump-out area. Should be two layers of 3/4 plywood in there. The rest of the transom is solid glass but thin, as you discovered.
I'd leave the existing plywood core, redo the keyholes, and laminate two layers of 3/4 coosa over the entire inside of the transom, using filler or oddball pieces to bring all the levels up. I would then also build some coosa knees to tie the transom to the top of every stringer. On my 1979 23 seacraft I installed an armstrong bracket on, I did three knees. One to each of the tops of the large box stringers, and another to the center stringer.
I would also remove the bracket from the transom and grind off the bottom paint and re-bed the bracket to the hull NOT to the top coat of the existing bottom paint, which is how it looks.
With the bracket off you could also dig out the transom core from around every bracket bolt hole and fill with thickened epoxy and re-drill. Then the core would be truly sealed and you would have nice solid chunks of epoxy in the transom to tighten the bolts to.
Just my .02 cents USD.
Loving your videos, as I do a lot of systems and structrual work, but am just getting into the refinishing aspect of boat work. Learning a lot from you about gelcoat and paintwork. Keep up the good work!
Build it out & roll with it. In 35-40yrs you won’t be worried about boats at that time! Go get it done & enjoy it, summer time is around the corner. While we are all still here, go enjoy as you much as possible. Stay safe & keep the good videos rolling! 🍻⛵️
Ok, I'm not a boat builder... But, if yo build up the top and sides to match the center section with whatever you would normally use... Then cut a 1" thick piece of (I'm going to say plywood. You probably know better material) to cover the entire transom and bond it all together and transfer the load across the whole area would that accomplish what you trying to reinforce...
Like I said... Don't claim to be a boat builder.
Option 3: Park the Bertram in your front yard, fill it with dirt and plant flowers in it. Then, buy a brand new boat and start making videos of you wrecking people holding a rope behind it! BAHAHAHA!!
My question to you is gonna be!!! Whats gonna give YOU the GREATEST peace of mind! what is gonna be the strongest, as others have said if it aint broke dont fix it! but if this is gonna be for you and your family, then you have to do what you believe is gonna be best. I would build up the low area and then finish the whole area with the coosa like you described. Take care and be safe.
Why the dewaxer worked is not because of the xylene necessarily, but the fact the surface of the old glass was not properly prepared for the G10 and 5200 that was added on top. The wax on the surface of the glass then was broken down by the xylene and BAMM! No more bond and it peels off fairly easily. I have used 5200 and wiped the top off it down with xylene and not had it deteriorate.
Getting ready to do the transom on my 26 CC and binge watching all your videos. Appreciate the effort taken to film and starting your channel.
A tip for removing the Armstrong bracket; support the bracket with your hoist then use a long piece of 80lb mono or braided fishing line, tie some sticks around the ends and wrap it around the joint and saw trough the 5200 like butter. When you remount the bracket leave a new rip cord for the next guy before you use your 5200 or boat works similar. Looks Good, Bill W
Two words: reciprocating saw. I know the old core is fine... now. But it doesn’t seem like any greater level of effort to replace the existing vs. building up the existing. The only difference seems to be the demo, which is the fastest & easiest part. Once the demo is done, you’ll have larger pieces of solid Coosa which will likely outlast all of us. My $0.02.
Leave the ply alone! Thicken it up and feather the edges toward gunwales to remove the stress area
Don't fix what isn't broke. I'm sure you'll seal it properly and it will last forever. Beef it up and keep up the good work! Love your videos.
Rip it out!.
If you are going to build up the top part anyway, it can be quite easy, too:
Take the platform off and cut out the thick part of the transom completely. Then you can use the remaining top part as the guide to fit in the lower plate of Coosa all the way from the top to the bottom and put the wider covering plate of Coosa from the inside over the whole width of the transom as planned.
All you have to do then is glass the transom from the outside, but that should be a no-brainer for you as you will have the new Coosa core to build up against. Glass up and finish the rest, remount the platform - job done!
Refitting the whole rest of the boat with Coosa and fiddling around with two different materials in the core, of all places at this part of the boat where you have the highest loads and stress for the material, is, imho a false compromise.
Taking this radical solution will give you a rock solid foundation for refitting the platform, and it's risk free as far as moisture is concerned. You are doing such a great job with the rest, paying so much attention to detail - to my mind you shouldn't fall short here. No second guessing with peace of mind!
Love our channel! Done some binge-watching as I am bound to refit my 1974 Lanaverre 590 - a small French daysailer. I feel so inspired by your channel, thanks!
Greetings from Hamburg, Germany,
Mark
As far as the transom per se, I doubt it matters structurally which method you choose. I'm confident you can do either correctly or make it look fantastic. Consider doing whatever is less time consuming. Now that the dead and live live loads (especially thrust) you've added to the transom by using outboards will be adequately supported by the transom, the concern is to ensure that the these loads will be transmitted to the stringer system and hull bottom/sides adequately to prevent over stressing the stringer/hull frame (racking and flexing). Great project Andy. Love the series.
1970’s/80’s technology and engineering isn’t as good as today’s. Cosa is a far superior product. I think you know this and is why your really thinking about doing this. It’s a lot of extra work but in the long run you know you’ll have piece of mind.
You are replacing the plywood with Coosa .That was your original plan for the entire boat. Don't wimp out now. I would like to see the process. Is that not why your channel exists ... Process and Procedures not turning out quick jobs for customers
Leave it there and build up on it... too many hours in labor going the other way and that is if no mistakes are made...do not create more work for yourself than you have to....Bring Out Another Thousand....Good Luck!
I'm no boat builder or engineer or anything... So take my opinion with a grain of salt. If it's going to cost more (i.e. time and effort) to rip out the old transom, than say- to add material for the thickness required, I'd say just leave the old transom in. As you said, you feel it's still a viable transom. But, I can see your point with ripping out everything and starting fresh. There's the rub I guess- which decision will end up being easier and less costly in the end? Hmmmm... Quite the conundrum.
If your plan is to keep it forever and ever I’d go all coosa and year out the plywood. Just my thoughts......
Andy, don't spend all that time and headache ripping out the plywood. Since the plywood is dry then it will be fine like you say for 20-30 years, it makes no sense to remove it. I'd say just thicken it up with the new foam boards, enlarge the holes and fill them with epoxy and re-drill them to the original size so the plywood stays fully sealed. It will be more than strong enough. Love the attention you give to these projects, really great workmanship !
A pair off Suzuki 350 HP motors weigh at least 660 kg plus all fittings ect. Other brands similar .And weight in a totally different place to inboards. Where engine is carried on the bottom . replace whole transom or you won't get insurance or peace of mind
Talk about digging in :P too bad you don't have a pair of I/O's at this point. Building up probably less $$$ in materials, all new more $$$ in materials. All the odd cutting to build it up, or all fresh with layups and what not might be close time wise.
Xylene is a VERY typical solvent for all kinds of things. Go buy a gallon at the usual scumbags and use that instead of that expensive total boat stuff. I agree using the Cleaner/Dewaxer for what it is intended for, but for what you are doing...yea, go get a gallon of Xylene instead.
I heard ya start to quote Ave at 13.55... nice.
I would think sanding, layering another core and glassing it all in wouldn't be a bad thing. If the core isn't damaged, let it be. It was made right and sealed properly.
Do you have, or could you make, a video on the different materials you use and the tools as well. What they all do and how they're used? Kind of a fiberglass 101. You're the best fiberglass teacher on UA-cam
I would build off of the core you have NOT!!! I changed my mind because the repair done by someone else was not done right the other repair may be the same. So I would have to rip it all out so I know it’s strength and that it’s sealed properly. Take it down to the outer skin then start building it stronger. Thanks Andy 👍👍💰
What would be the most efficient way? What would be the most satisfying way. If building over will work and your happy with it, go that route. If blowing it out would help you sleep better, go that route. Myself, sleeping better is always the better route in the end. Even if it seems unnecessary.
Doesn't plywood offer more strength than coosa? How many layers of 1708 will be needed to build up the strength you need?
Build it up/reinforce it. Don’t reinvent the wheel. Make it safe and functional.
With the amount of horse power and weight and torque that will be applied to the back of the boat. Basically a fully loaded ( or possibly over loaded boat 6 fat dudes drinking) gear and such. Hammering down on the throttles ( we don't all ease off the docks). 1/4 inch fiber glass? really? honestly Chainsaw the back off. glass in a new transom. be faster then trying to match up and fill in the cracks. Your work is most excellent but as you know each join is a potential "leak/weep" point and the amount of fairing oh la laaa. Yes that seems a bit extreme. As my father would say. The best path is not always the most easiest. by moving the motors that far back. your going to be basically lifting the entire boat by the transom. then add chop of water bouncing the boat up and down. I fear that your going to put undue force on it and unless it has a VERY stable and secure transom. your going to have many "stress cracks" and later water intrusion and delamaination issues. I mainly work on old slow sail boats and I am often surprised by the amount of stress those boats and their hulls are under.
Andy the Hull was built for inboards not twin outboards on a bracket. If you just had the outer skin right now, how would you build the inside of the transom up to your desired thickness? 3" of coosa and a thick well laid up inner skin with offset tabbing or various thicknesses of plywood and glass, and some pine for the keyholes? I'm sure you could find out what Bertram would recommend or get the opinion of a naval architect or engineer. Maybe not a situation for "well it lasted this long it should be good." Lake Superior is cold and deep even in the summer.
Hi Andy
Great comments Everyone both for keeping it fixing up the old to handle the new outboards or completely removing the old and in with the new. For me and my blue collar money and time I would fix it as is and get my family out in the water before they go to college my boys are six and eight but if money and time is not your issue and you just called your Ranch manger to have him rotate you Polo Ponies for this weekends Match then by all means replace all the old wood and replace the entire and stretch it to 31 foot because everyone know that the 31by10 Bertram is the woulds best hull and reinforce it to handle Four 350hp V8 Merc racing motors and blow by the Yacht Cub at a hundred and twenty Bata Bing Bata Boom.
I have never seen a plywood core that didn't saturate. Your boat maybe was stored out of the water most of its life? Through fasteners leak and are a point of entry for water and it would seem no matter how well they are sealed and bedded. And there is always something that has to be mounted, the newest latest and greatest, trolling motor brackets, tow eyes, trim tabs, etc. etc. also inside brackets for pumps down in the bilge and a myriad of other things will allow egress of moisture over time. In more than sixty years of working around boats this is the way it is. Case in point those Armstrong mounting bolts looked like they had a good amount of 5200 sealing them yet you found the leaks seaping in through the entire thickness of the transom. Who knows how much just entered and was absorbed at the plywood? As has been proven with fiberglass 'blisters' fiberglass is not impermeable to water. The more draft the more pressure forcing the water into the glass. Even the new 'barrier' coats are not given with a 100% guarantee over time. You are close enough now is the time to get it out. It will never be easier. The coefficient of expansion on metals and fiberglass is also going to contribute to breaking any watertight bond pretty quickly with your hot summers and super cold winters. Nope I would take it out. Several good techniques on doing that which make it pretty quick. Boatworks Today down in Florida did a series on a very similar boat and transom repair covering it. Several others have tackled the job. Comes out in pretty large chunks. Where it is saturated it quite literally falls out once the fiberglass is removed. When rebuilding the transom set in solid epoxy (check Gougin Bros printed material on how) in areas where you are going to have bolts to prevent compression (another cause of leaking). Now you can rest assured it will last a lifetime. Take care. Doug
Leave the plywood. While Coosa doesn't rot it is only marginally better than plywood when the core gets wet. Any water intrusion combined with action of the fiberglass will create internal hydraulic pressures that will create delamination of the Coosa. Their is no perfect core.
JJ
A lot depends on what your hanging on the back . if 1000 HP + or 4 outboards do not skimp anything .out and replace with largest sheet sizes possible
Repair keyholes, add an inch more to the overall thickness of the transom, then add a glassed in strong-back just above keyhole height across the transom and forward on each side 18" or so.......
Despite the backyard job done to try and stiffen up the transom, the original core is still in good nick even with all the bolt holes drilled through it. For me, I'd keep the original core and anywhere you have to drill through the transom, overdrill the holes, backfill with thickened epoxy and then drill (when fully cured of course) to the final required size. The good old..."drill, fill, drill" technique. I would do the the backfilling before you proceed with the additional Coosa stiffening then do the final drill after the stiffening work is done. In my mind, doing it this way it will give you peace of mind that you have completely sealed off the interrnal ply core from the elements. A whole lot easier than spending day after day after day trying to remove a perfectly good core.
Either all ply or all coosa. As long as the existing ply is dry, I don't see where you can go wrong either way. But If you leave the ply there's no reason to use coosa for your work.
Oh and for removing ply coring get an aggressive wood carving burr for your 4.5" grinder. Once I get the glass off, I can have the core cleaned out in no time. Guards from going too deep with saw too. While it will remove glass it's dramatically slower than wood so you get the benefit of fast wood removal and the safety of being able to hit the glass without doing immediate damage. Just make sure you don't loose control of the tool, it removes skin just as fast, guess how I know.
www.woodcraft.com/products/kutzall-extreme-dish-wheel-4-1-2-diameter-very-coarse-dw412x120?via=573621bd69702d0676000002%2C573621da69702d0676000d03%2C5763fe9869702d6582000b71