I remember when you first showed up at Lionel's Back Yard Metal Casting forum. We all thought you were crazy! Showing up having not cast anything, saying you would cast a prop like this. Inspiring determination, Doug.
Shafts will alway have harmonics. When you spin them up they go through criticals when that happens the shaft will actually bowes slightly. Ones it goes through it straightens out. When you balance it your actually balancing the bow out of it. What you are doing is called a static balance. A dynamic balance you would need a balance machine for. Most decent machine shops can do it for you...maybe even a driveshaft shop. The only bonus would be is lengthened cutlass bearing life.
@@SVSeeker There is balance machines balancing huge industrial fans. Probably the dynamic balance dont affect this so much because the prop doesnt spins so fast. It also depends where the 100 grams difference sits on the blade. You can balance static, instantaneous and dynamic. Static is sufficient.
There’s a procedure for balancing propellers I learned from hovercraft building. Put the shaft on a knife edge to eliminate friction. The heavier blade will rotate to the bottom. Then you can fine tune the weight of each blade until it is perfectly balanced and will not rotate on its own anymore.
Car wheels I dynamically balance on a machine, spinning it up and putting weight on both sides of the wheel. My motor cycle tyre I balanced static on rollers and its perfectly fine too. I do believe this static trick aka having the 3 prop blades the same ish weight will be more than good enough to not have any problems. The wobble on the stand will show even a tiny imbalance but the boat won't move that easy so even this 100 gram imbalance would probably be just fine
@@timstewart8690 it’s still better than just measuring the weight of each blade in that it takes the centre of mass into consideration as well. I’d match the blades closely on the scales & so a static balance.
I believe a static balance would be fine,dynamic balance is for two planes, and with the variable pitch if you balance in two planes it will increase as pitch is increased. You would chase it forever. Have you ever used thordon instead of rubber for bearings. Man that looks good.
The beauty is that you don’t have to say how you would do it. You can just do it. To your own propeller. To lead by example rather than armchair quarterbacking.
I wasn’t suggesting leading from here. I’m suggesting doing something as opposed to talking about what you’d do differently if you weren’t just second-guessing someone who’s doing something.
A tug I use to work on had a Busch-Sulzer Diesel, it had an RPM chart, 0 - 400 with a notation that 275 was a critical turn. It warned "Do not operate at 275 RPM." When we passed 275 RPM there was a noticeable shake in the whole boat. If you end up with a critical turn, stay away from that RPM. You may find you are fine above or below that turn. Happy New Year!
that rpm is just where the harmonics of all turning things come together. It can be pretty dangerous but sometimes just adding a counterweight to the "gearbox" might fix it because of a change in frequency. Thats how they fix in in modern cars, just add a block of metal on a bracket and it might have gone away(probably calculated/simulated in some software first)
Torsional vibration could also produce some no-go rpm ranges, or does the hydraulic transmission overcome that ? Recalling here in my youth being in charge of an 8 cylinder 600rpm Allen Diesel generator and discovering playing with the governor produced some speeds that were very unhappy and that previous technical lectures on crankshaft balancing, harmonics and torsional oscillation had some practical use .
@SV Seeker. The problem is. If there is any shake at all. The shaft will walk around the rear wet bearing instead of spinning in it. It will ruin the shaft and the cutlis real fast.
Watching him spin that prop brought back memories of the old videos of those inventors that did not do so well. Kept waiting for the prop to go spinning across the grass and through a wall!
You're over thinking it Doug. This is just like balancing a wheel. Think of it as a fixed assembly. Take weight off the heavier blades to match the lightest blade. You're only going to be able to to a static balance in the axial plane only. Without much better measurement equipment you won't be able to eliminate dynamic vibration. You're correct about the harmonics, but I would say the imbalance you currently have IS significant because it's going to cause incremental and ongoing premature wear to your bearings. Great work on it though. Your engineering style and work arounds continue to impress me.
Actualy the stand moving allows you to balance at speed.... You bring it to the rpm that causes that stand to move then you bring in a marker to the rotation of the blade at the outer edge until the heavy side just touches the marker.... Then you will have marked the heavy point.... First static balance blades tip to base then static balance with the blades on the shaft and the shaft resting on sharp blades like scraper blades or planer blades... I can accurately balance for 100 thousand rpm this way as in jet engine turbines... You will need to remove weight from the center of balance of the tip to base
my neighbor was a turbine mechanic and he would tell me that the harmonics would cause the turbines to vibrate at a certain speed. you had to spin the turbine past the harmonic or else they would literally explode. main thing is to not let it sit in the harmonic speed. but then again you probably know all this. Love the Vids. cant wait for them to come out.
The whole system will have various balance points, based on the harmonics of each component. You can probably just tune your use of them, by making sure that you don’t run them at the speed which triggers the harmonic resonance. DAMN, you just said those words!
I’m over here building model aircraft carriers and this guy is building a whole boat in his front yard, first time watching your channel, looks awesome keep up the great work
Long time watcher, first time injecting my $0.02. Everyone is right about the static balance of each individual part and the dynamic balance of the assembly as a whole. We always referred to critical rotation/harmonics as knowing the natural frequency of your shaft assemby in my refinery days. And it seems like you found it for both prop sets around the 200-300 rpm marks. Low rpms won't push you into needing a really tight balance, but it will improve your reliability in seals and bearings. I bet you can find a good way to be more precise the more you think about it. It seems I'm always learning something new from your videos. Props to ya for this one, haha!
I was feeling pretty good about myself this afternoon. I, while taking a break, made some coffee. I grinded my own beans, put the ground beans into my coffee maker, added water and turned the coffee maker on. I, as I said, was feeling good because the coffee I made was tasting OK as I logged on to UA-cam. I was sipping coffee and clicking around until I came across some whacko that is building his own bad ass sailing ship in his front yard! It, by comparison, made the grinding of my Starbucks coffee beans seem like not such a big deal. My coffee, in fact, all of a sudden wasn't that special so I, just to make myself feel better, gave the sailboat video a thumbs down and found a video of a cat that was slipping then and fell off of a counter top. I, again, felt good about myself. I've never slipped off of a counter top and I bet that cat can't grind HIS own beans! PS In all seriousness this is (maybe) the most totally awesome project I've ever seen and it inspired one of only three UA-cam comments I've ever made. It's got my thumbs up and I am subscribed. - Signed 'Blown Away in Miami'.
Doug, you never cease to amaze me. I have managed to cobble most of my mistakes together to make them work, you, on the other hand figure out how to make things work properly
And now the me watching your videos has come full circle, right back to the propeller. And I was just doing research on bronze casting to make a khopesh the night I found your casting videos.
I had a Torque-Shift variable pitch prop on my runabout. It operated by springs, cams and water pressure. It worked very well. Come out of the hole at 11 pitch and switch up to 21 or 22 pitch. Sold the boat years ago, still have the prop somewhere.
i used to work on small offshore supply boats...just under 500GRT...and all of them, even the newer ones had some vibration at a particular rpm, usually low-mid range...some barely noticeable, others felt like the boat was falling apart...so many variables to take into account its really trial and error till you get it "perfect"...but hey for 600revs on a couple wobbly stands, i'd call that good enough! keep doin your thing Doug lookin forward to seeing her in the water soon!
When you were spinning your shaft and prop fast. I set and watched a range, the propeller tips against a spot on the green trailer chassis. The prop tips were spot on, no wiggle, no hopping, very true. Just an observation...
Boy would I love to come and join you for a little bit and help out. I would love to come and be on your beautiful vessel that has slowly been coming to fruition in the most amazing ways. Been a fan since the beginning, I can’t wait to see how this beautiful machine turns out!
Welcome to the phenomenon of _resonance._ If it 'comes and goes' through a consistent RPM window, you COULD use a heavy viscous coupling but that might be more complicated than just a good balancing and brute force bracing.
You're amazing to me. What you're doing is phenomenal. I'm very happy to see another video from you. Ill be sad when you're finished but so proud and happy for what you and your crew/family/ friends have accomplished. Be safe always and keep inspiring people everyday!
Clever... I knew of how to check center of gravity on a dual blade propeller, like what you would find on dinky airplanes.. But never once, did I ever think about the center of gravity for each blade.. I am blown away by that.. really clever...
As a fellow boat building(rebuilding) youtuber, I thought I get a lot of comments telling me I'm doing it wrong etc. My comment is do whatever you want. It will work, and if it doesn't you can fix it cause you built it. 👍⛵
To balance the blades you could hang the 3-blades set vertically close to the ground and measure the distance of each blade from the ground. Add weight to the blades appropriately until all blades are the same distance. I have done this for wind turbine blades, it worked great.
After this coming summer’s launch and tests it will be interesting to hear your thoughts on “what I should have done” or “ hey that works better than I thought it would.” The amount of engineering you’re done on Seeker is impressive especially when you think of the huge teams of draftsman, engineers, designers, craftsman it takes to develop and build anything this complex. I realize this is the boat the internet built but you had to manage and collate all that information so it would be nice to have a “lessons learned”.
@@leeklemetti1887 True! I have watched most of them but then again that boat is still high and dry and hasn’t lived through any rough water. Lots of stresses that are only theoretical at this point.
I spent two years readying a sailboat for a big trip, and thought I had everything planned. Nope. I learned a lot of lessons that I will apply to my next endeavor though.
Two things I kept considering watching this whole video, Love seeing your work by the way. One is the best way to figure the pull of an unbalanced spinning object, is a grease pen. Come close to the object without touching it until it touches the grease pins. That would be the heaviest point from your axis. Obviously not the blades lol but I would test it maybe three or four feet down. I was also wondering if the smaller amount of grease not being equally distributed along the inner shaft could possibly be that many grams off which would also explain why it levels out later.
Another informative video! I especially enjoy seeing the way you work around maneuvering heavy objects. I guess necessity is the mother of invention when you're alone and need to keep pushing forward!
You are correct of course that the weight difference closer to the edge versus the shaft is the cause. Weigh each blade with one end on the scale, then the other end on the scale. Write it down and note which blades have the closest discrepancy ratios. That is, the most similar outer weight to inner weight ratios. They should all also have the same weight overall. You can grind them to create that. In fact you can use the grinder to alter the inner- outer weight ratios as well.
any decent propeller shop can balance that for you. We have one in Savannah GA (champion Propeller) they have always done mine. It would lengthen the life of the whole assembly. Plus it would not be good to have a bad vibration after you have launched it. I've put brand new 18 inch props on and had vibrations, had to take them back off and have them balanced for a smooth ride. You have an amazing story, I wish you well in your travels.
@@SVSeeker completely get it and you have done amazing work. Just sometimes you have to have equipment to do certain task that are needed but not worth the investment to do yourself. You can certainly put it in the water and test it and risk having to pull the boat back out the water to have it done. If you were just cruising the coast I wouldn't be concerned too much. But from your videos you have plans of taking off on some extensive traveling. Repairs in other areas may be more difficult and more expensive then doing now. The wobble in the shaft looks concerning also if it is not trued then your bearing will not last long at all. Just a suggestion. Much respect to the job you have done. It looks amazing.
hey seeker and co happy new year. my knowledge on marine shafting is minuscule ..keith fenner knows and is probably a good resource for you to make use of..
While this is true, the heaviest one could also have the most weight at the base of the blade. It turns out that the distance from the point of rotation actually plays a large role in how things balance as well as weight. It's called moment of inertia if you want to read more about it. In short, it's important that the center of mass is the middle of the shaft for the assembly. Or, the same distance from the base on each blade.
@@Akya2120 Center of mass distance from the point of rotation is the only thing what matters = moment of inertia. It does not matter if the heaviest one have the most weight at the base of the blade.
@@deadslow201 it actually does the moment of inertial is some constant times mass times the square of the radius from the axis of rotation. Literally the distance at which the mass is located from the center is exponentially more important. As I said, while getting them to all weigh the same is important, getting the mass to be evenly distributed is more important.
Doug, I haven’t noticed if you had already done this or if it’s even possible but what about putting a large ball valve on the propeller shaft tube just in case you had to pull the shaft completely out while in the water or while seeker is on her keels and the repair takes more than a day and the tide will come up again... you usually think of everything and have a plan, but this just popped in my head. Thanks for sharing. Edit: I even had an afterthought for just a big rubber plug lol just in case you had the cutlass bearing out. Paint the plug red and keep it with your puller.
To test the blade balance, using your CNC capabilities, make a "jig" that would allow all three blades to be mounted, at 120 degree separation, with a pilot hole of about 3 inches in the middle. Once the jig is finely balanced, mount the blades and set all the angles the same. Then mount the whole contraption onto an automotive "bubble" balancer. The position of the bubble would give you the heavy incidence and you could adjust accordingly.
RC model airplane builders use a similar rig to balance their props. The heavy blade always stops at the bottom. Remove a little material from the heavy blade. When the prop stops in random locations when given a push its in balance. This works fine for rc motors spinning at thousands of rpms. You may want to use bigger rollers like bicycle tires to make it more sensitive. Offset the wheels so the shaft contacts on the upper half of the wheel circumference. You wont be spinning the prop fast at all in this rig just a push by hand to get it moving. The prop will act like a pendulum.
Long time viewer, first time caller. This is scary to me - and it's the first of your videos where I really feel that way - I generally agree with your stance on safety. I think there's a risk here you didn't account for - if it fell off the stand the prop would, as you say, go north. But when that happens, the shaft would rotate around it's center of mass, sending it's other end south - into you, holding the rpm meter. Even if I'm wrong about all that, the amount of kinetic energy there is over the top. I wouldn't want to be anywhere near it.
I would go where that happens. 100 year old English rebuild next to an American build Chinese junk ship from OK. Both re/built in America. Love it, please post the meeting location.
I think I just found my new favorite channel!!! Your right on track with the balancing of the props and I think the vibration was coming from the tale end of the shaft not being supported do to gravity pulling down on the end while rotating... just a thought thou!!! Luv what your doing!!!❤️❤️💪🏼👊🏼👍🏻🤣🤣🤣
I used to ballance C-130 Propellers. Before we had the high tech sensors we ballanced them the same way car tires used to be ballanced. Horizontal on a pin and we added the ballance weights on the hub. Might be worth exploring.
get a piece of chalk, and gently touch it to the front nose while its spinning. the high point (heavy) will leave a mark, place a trial weight on the opposite side and repeat. etc
Doug i have a 38 foot cape island fishing boat and had a wobble in shaft of the boat it’s not variable pitch but not only did I ruin every bearing and cutless but also the transmission I’m running a 220 John Deere so pretty much the same hp as you think you have a 210 Cummins just a heads up is all I sent my blade out to a foundry in Nova Scotia and they polished and balanced for 400$ fixed everything no problems after it was done
Wow, this is a great project. I can mostly tell within a minut or so if a vid is gonna bore the pants of me or if the guy that made it knows what their talking about. In your case I kwew within 30 seconds: This guy is smart. Brilliant, thanks.
Now you've got me curious how they balance drive shafts for cars... I suspect having a balanced shaft is important as well as having balanced blades. If you fire up the prop and the whole boat has a resonant frequency, you'll know where it's coming from! Hell, that might be kind of nice to have a little hum once in awhile. Top shelf Doug!!!
They spin them on a balancer like everything modern these days and apply weight or remove weight as necessary. Local shop in Georgia charges $120 to shorten and rebalance shafts.
Think Tacoma Narrows Bridge Collapse - when the vibrations for a given structure resonates to the point where the amplitude begins to increase continuously to the point of destruction. This typically occurs when the natural frequency of the support structure and the rotating vibration ( inducing force) (wind in Tacoma Narrows case), excites the structure, growing in strength. There is such a thing as a critical speed and machinery should avoid lingering at or around this rpm. Move the throttle quickly past this point when speeding up or slowing down. As stated by many commenters vibration reduces bearing life, the lower the better. I That said your test rig set up did actually depict the bearing support configuration found when in the vessel so it likely you won’t see the vibrations at the same rpm or at all. My suggest is to get the weight as close as possible in a static condition and call it good.
I don't know if you look at comments from videos five months ago but I didn't remember this until the blade started spinning on that stands that you had but I just wanted a comment that one of my favorite sounds in the whole world is that sound of the grease going squishing pop and it's like you can't really describe the noise you have to make it and the best way to do it is with the s*** ton of Grease ciao for now
I would mark with a punch the center of gravity on those blades now while your out of the water just a suggestion. It was pretty impressive to see six hundred rpm on that setup! pretty cool it was moving. Happy New Year Doug.
Talk to an AME. A prop balancer will work. Also, that 120 grams will make a significant difference on your bearing life!!! I would start with static balance (blade weights) then finish off the dynamic balance with an aircraft prop balance.
You guys continue to set the bar for playing things fast and loose, pun intended! I understand just leaving the shaft lay in the bearing but I would have thrown a few sandbags on both of those uprights as an insurance policy. I know you don't care much about the safety aspect but that's a lot of work to redo if that thing comes apart.
Damn! It’s great to see savvy back yard mechanics doing stuff with a combination of low tech, high tech and common sense. That’s a recipe for innovation and adventure.
Run the shaft without the blades then see if it vibrates. As a helo pilot you are really trying to get something difficult done. Congratulations on the progress!
I remember when you first showed up at Lionel's Back Yard Metal Casting forum. We all thought you were crazy! Showing up having not cast anything, saying you would cast a prop like this. Inspiring determination, Doug.
Shafts will alway have harmonics. When you spin them up they go through criticals when that happens the shaft will actually bowes slightly. Ones it goes through it straightens out. When you balance it your actually balancing the bow out of it. What you are doing is called a static balance. A dynamic balance you would need a balance machine for. Most decent machine shops can do it for you...maybe even a driveshaft shop. The only bonus would be is lengthened cutlass bearing life.
I doubt you'd find a drive shaft outfit that would ever consider swinging 100 pounds of blades. : )
@@SVSeeker Ask...
@@SVSeeker Assumption is the mother... something something :)
@@SVSeeker There is balance machines balancing huge industrial fans. Probably the dynamic balance dont affect this so much because the prop doesnt spins so fast. It also depends where the 100 grams difference sits on the blade. You can balance static, instantaneous and dynamic. Static is sufficient.
I’m not qualified to add any information but it sounds like what you are saying makes sense
There’s a procedure for balancing propellers I learned from hovercraft building. Put the shaft on a knife edge to eliminate friction. The heavier blade will rotate to the bottom. Then you can fine tune the weight of each blade until it is perfectly balanced and will not rotate on its own anymore.
That's known as static balance.
Dynamic balance is a different kettle of fish. : o)
That is the minimum what he could do.
Car wheels I dynamically balance on a machine, spinning it up and putting weight on both sides of the wheel. My motor cycle tyre I balanced static on rollers and its perfectly fine too. I do believe this static trick aka having the 3 prop blades the same ish weight will be more than good enough to not have any problems. The wobble on the stand will show even a tiny imbalance but the boat won't move that easy so even this 100 gram imbalance would probably be just fine
@@timstewart8690 it’s still better than just measuring the weight of each blade in that it takes the centre of mass into consideration as well.
I’d match the blades closely on the scales & so a static balance.
I believe a static balance would be fine,dynamic balance is for two planes, and with the variable pitch if you balance in two planes it will increase as pitch is increased. You would chase it forever.
Have you ever used thordon instead of rubber for bearings. Man that looks good.
I would get the balance as perfect as possible, it will extend the life of your bearings and improve your engine performance.
captain obvious lol
The beauty is that you don’t have to say how you would do it. You can just do it. To your own propeller. To lead by example rather than armchair quarterbacking.
@@davidgray7907 098
@@ButterflyMatt how does one "lead by example" from the UA-cam comments section lol? What a preposterous suggestion
I wasn’t suggesting leading from here. I’m suggesting doing something as opposed to talking about what you’d do differently if you weren’t just second-guessing someone who’s doing something.
A tug I use to work on had a Busch-Sulzer Diesel, it had an RPM chart, 0 - 400 with a notation that 275 was a critical turn. It warned "Do not operate at 275 RPM." When we passed 275 RPM there was a noticeable shake in the whole boat. If you end up with a critical turn, stay away from that RPM. You may find you are fine above or below that turn. Happy New Year!
that rpm is just where the harmonics of all turning things come together. It can be pretty dangerous but sometimes just adding a counterweight to the "gearbox" might fix it because of a change in frequency. Thats how they fix in in modern cars, just add a block of metal on a bracket and it might have gone away(probably calculated/simulated in some software first)
Torsional vibration could also produce some no-go rpm ranges, or does the hydraulic transmission overcome that ? Recalling here in my youth being in charge of an 8 cylinder 600rpm Allen Diesel generator and discovering playing with the governor produced some speeds that were very unhappy and that previous technical lectures on crankshaft balancing, harmonics and torsional oscillation had some practical use .
I have been a pipe fitter for 25 years. I've learned a lot just by watching a few of your videos please keep up the good work.
I’m back after several years.
It was awesome watching you test the prop shaft and blades.
Excellent craftsmanship!!
At A&P school we had this propeller balancer thing and we got the balance within .5 of a gram. Made the engine run much better.
I balanced rotor blades for helicopters. It is extremely important and will make parts last longer and decrease vibration.
@@dvdadaudits7500 i agree but its only 600rpm maximum. 1 gram put of balance at about a 2' off centerline is only 1lb. 6000rpm and its 100lbs.
@SV Seeker. The problem is. If there is any shake at all. The shaft will walk around the rear wet bearing instead of spinning in it. It will ruin the shaft and the cutlis real fast.
Watching him spin that prop brought back memories of the old videos of those inventors that did not do so well. Kept waiting for the prop to go spinning across the grass and through a wall!
I highly recommend all Dave Gerr's books on boats - full of expert and practical knowledge.
You're over thinking it Doug. This is just like balancing a wheel. Think of it as a fixed assembly. Take weight off the heavier blades to match the lightest blade. You're only going to be able to to a static balance in the axial plane only. Without much better measurement equipment you won't be able to eliminate dynamic vibration. You're correct about the harmonics, but I would say the imbalance you currently have IS significant because it's going to cause incremental and ongoing premature wear to your bearings. Great work on it though. Your engineering style and work arounds continue to impress me.
Actualy the stand moving allows you to balance at speed.... You bring it to the rpm that causes that stand to move then you bring in a marker to the rotation of the blade at the outer edge until the heavy side just touches the marker.... Then you will have marked the heavy point.... First static balance blades tip to base then static balance with the blades on the shaft and the shaft resting on sharp blades like scraper blades or planer blades... I can accurately balance for 100 thousand rpm this way as in jet engine turbines...
You will need to remove weight from the center of balance of the tip to base
what ed says
Take it to a driveshaft specialist
Bernoulli's principle (when a fluid meets a restriction the fluid velocity is increased, with a proportional decrease to pressure)!
Highly recommend you have the shaft straitened and the prop balanced. It will shaft you headaches in the future. I worked/owned a prop shop years ago.
Not supposing to hear form someone who was paid for it. :)
@@YoloSwagNinja Pumpkin, I've not stopped listening to people with biased views. I never did listen to them. :)
my neighbor was a turbine mechanic and he would tell me that the harmonics would cause the turbines to vibrate at a certain speed. you had to spin the turbine past the harmonic or else they would literally explode. main thing is to not let it sit in the harmonic speed. but then again you probably know all this. Love the Vids. cant wait for them to come out.
The whole system will have various balance points, based on the harmonics of each component. You can probably just tune your use of them, by making sure that you don’t run them at the speed which triggers the harmonic resonance. DAMN, you just said those words!
I think you could engineer that out of the system with some springs and some weights on the shaft, like an old school mechanical speed governor
I’m over here building model aircraft carriers and this guy is building a whole boat in his front yard, first time watching your channel, looks awesome keep up the great work
Holy cow! there's some serious energy stored in that prop! Scary but fun!
Long time watcher, first time injecting my $0.02. Everyone is right about the static balance of each individual part and the dynamic balance of the assembly as a whole. We always referred to critical rotation/harmonics as knowing the natural frequency of your shaft assemby in my refinery days. And it seems like you found it for both prop sets around the 200-300 rpm marks.
Low rpms won't push you into needing a really tight balance, but it will improve your reliability in seals and bearings. I bet you can find a good way to be more precise the more you think about it. It seems I'm always learning something new from your videos.
Props to ya for this one, haha!
I was feeling pretty good about myself this afternoon. I, while taking a break, made some coffee. I grinded my own beans, put the ground beans into my coffee maker, added water and turned the coffee maker on. I, as I said, was feeling good because the coffee I made was tasting OK as I logged on to UA-cam. I was sipping coffee and clicking around until I came across some whacko that is building his own bad ass sailing ship in his front yard! It, by comparison, made the grinding of my Starbucks coffee beans seem like not such a big deal. My coffee, in fact, all of a sudden wasn't that special so I, just to make myself feel better, gave the sailboat video a thumbs down and found a video of a cat that was slipping then and fell off of a counter top. I, again, felt good about myself. I've never slipped off of a counter top and I bet that cat can't grind HIS own beans! PS In all seriousness this is (maybe) the most totally awesome project I've ever seen and it inspired one of only three UA-cam comments I've ever made. It's got my thumbs up and I am subscribed. - Signed 'Blown Away in Miami'.
LOL I hope you write for a living
Gotta love the Sacrificial Safety Sofa set up to catch the spinning prop in case it came off the stands 🤣
He is playing with his shaft again lol
I learned a lot about propellers during this episode. Thanks Doug
Doug, you never cease to amaze me. I have managed to cobble most of my mistakes together to make them work, you, on the other hand figure out how to make things work properly
And now the me watching your videos has come full circle, right back to the propeller. And I was just doing research on bronze casting to make a khopesh the night I found your casting videos.
I had a Torque-Shift variable pitch prop on my runabout. It operated by springs, cams and water pressure. It worked very well. Come out of the hole at 11 pitch and switch up to 21 or 22 pitch. Sold the boat years ago, still have the prop somewhere.
i used to work on small offshore supply boats...just under 500GRT...and all of them, even the newer ones had some vibration at a particular rpm, usually low-mid range...some barely noticeable, others felt like the boat was falling apart...so many variables to take into account its really trial and error till you get it "perfect"...but hey for 600revs on a couple wobbly stands, i'd call that good enough!
keep doin your thing Doug
lookin forward to seeing her in the water soon!
The idea with the rope for handling the shaft while getting it out... some things are so easy :)
Hey Doug, I made the first test cuts on my tiny cnc machine today. Fixed ( replaced ) a bad stepper driver. Love your boat, ship, vessel!
Prop housing design is fantastic!!!!! Dayumm
Also, my heart jumped a little when you measured the propellor blades in metric! :D
Don't get too excited, it was likely a cheap Chinese scale that didn't have the option for imperial units. Lol
When you were spinning your shaft and prop fast. I set and watched a range, the propeller tips against a spot on the green trailer chassis. The prop tips were spot on, no wiggle, no hopping, very true. Just an observation...
That prop is a thing of beauty.Nice work.
Doug, with prop speed like that you should win the America's cup! I loved the test.
The guy who helped you to put the shaft in thanked you for letting him help you.
maybe he bought him lunch for the effort? :)
Brilliant. What an adventure. Thanks SV Seeker crew.
Thanks for sharing all of this Doug. This channel really does amaze me of the human ability to learn and create.
Boy would I love to come and join you for a little bit and help out. I would love to come and be on your beautiful vessel that has slowly been coming to fruition in the most amazing ways. Been a fan since the beginning, I can’t wait to see how this beautiful machine turns out!
Welcome to the phenomenon of _resonance._ If it 'comes and goes' through a consistent RPM window, you COULD use a heavy viscous coupling but that might be more complicated than just a good balancing and brute force bracing.
Great demonstration of resonance frequency!
You're amazing to me. What you're doing is phenomenal. I'm very happy to see another video from you. Ill be sad when you're finished but so proud and happy for what you and your crew/family/ friends have accomplished. Be safe always and keep inspiring people everyday!
Clever... I knew of how to check center of gravity on a dual blade propeller, like what you would find on dinky airplanes.. But never once, did I ever think about the center of gravity for each blade.. I am blown away by that.. really clever...
Pure bloody genius. Good luck to you, your family & your project.
Consider that the blades will also differ aerodynamically when spinning in air, not just weight.
For some reason that 100lbs of spinning death made me nervous
Darken , 14,544 grams per blade it’s 43,632 grams or 96.192lbs of death
It made me so anxious watching that, imagine it starting to wobble and falling over into the ground, that could kill a man so easy.
@@aldousorwell4577 Ive watched Doug do alot of stuff, been watching for years, this is the only time I was scared for his safety lol
@@darken3150 me too, even I had one eye closed..
Doug's motto...Safety THIRD!
Wonderful "A-HA!" moment when you explained how to find the COG of the blade :)
As a fellow boat building(rebuilding) youtuber, I thought I get a lot of comments telling me I'm doing it wrong etc. My comment is do whatever you want. It will work, and if it doesn't you can fix it cause you built it. 👍⛵
Bart and Doug. What a team !!
i was hoping you were going to throw melons into that blade
SLICING BANANAS WOULD BE A hoot!
Use frozen fish 🤣
I was thinking an apple or a potato lol. Not worth messing up the blades though.
Almost spit out my beer... 😂
Youre editing is awesome! The explanation of the VP shaft was perfect!
To balance the blades you could hang the 3-blades set vertically close to the ground and measure the distance of each blade from the ground. Add weight to the blades appropriately until all blades are the same distance. I have done this for wind turbine blades, it worked great.
You definitely know what you’re doing!!!
After this coming summer’s launch and tests it will be interesting to hear your thoughts on “what I should have done” or “ hey that works better than I thought it would.” The amount of engineering you’re done on Seeker is impressive especially when you think of the huge teams of draftsman, engineers, designers, craftsman it takes to develop and build anything this complex. I realize this is the boat the internet built but you had to manage and collate all that information so it would be nice to have a “lessons learned”.
Just watch 100 videos. Job done.
@@leeklemetti1887 True! I have watched most of them but then again that boat is still high and dry and hasn’t lived through any rough water. Lots of stresses that are only theoretical at this point.
I spent two years readying a sailboat for a big trip, and thought I had everything planned. Nope.
I learned a lot of lessons that I will apply to my next endeavor though.
Congratulations I was expecting the thing to start hopping around as you got it going that fast!
This the best chief engineer...Thanks chief for this video..
I can't wait to see this Seeker in the water... !!!!!!!!!!!
Two things I kept considering watching this whole video, Love seeing your work by the way. One is the best way to figure the pull of an unbalanced spinning object, is a grease pen. Come close to the object without touching it until it touches the grease pins. That would be the heaviest point from your axis. Obviously not the blades lol but I would test it maybe three or four feet down.
I was also wondering if the smaller amount of grease not being equally distributed along the inner shaft could possibly be that many grams off which would also explain why it levels out later.
توتار. عناىاا
"You start cussin' at somethin' and it all of a sudden works for ya"
Ain't that the truth with these things!
Another informative video! I especially enjoy seeing the way you work around maneuvering heavy objects. I guess necessity is the mother of invention when you're alone and need to keep pushing forward!
You are correct of course that the weight difference closer to the edge versus the shaft is the cause. Weigh each blade with one end on the scale, then the other end on the scale. Write it down and note which blades have the closest discrepancy ratios. That is, the most similar outer weight to inner weight ratios. They should all also have the same weight overall. You can grind them to create that. In fact you can use the grinder to alter the inner- outer weight ratios as well.
any decent propeller shop can balance that for you. We have one in Savannah GA (champion Propeller) they have always done mine. It would lengthen the life of the whole assembly. Plus it would not be good to have a bad vibration after you have launched it. I've put brand new 18 inch props on and had vibrations, had to take them back off and have them balanced for a smooth ride. You have an amazing story, I wish you well in your travels.
Sort of missing the point of our DIY channel. : )
@@SVSeeker completely get it and you have done amazing work. Just sometimes you have to have equipment to do certain task that are needed but not worth the investment to do yourself. You can certainly put it in the water and test it and risk having to pull the boat back out the water to have it done. If you were just cruising the coast I wouldn't be concerned too much. But from your videos you have plans of taking off on some extensive traveling. Repairs in other areas may be more difficult and more expensive then doing now. The wobble in the shaft looks concerning also if it is not trued then your bearing will not last long at all. Just a suggestion. Much respect to the job you have done. It looks amazing.
Sometimes paying for perfection is worth it before the boat is in water. Find a shop that can do it. Better than wobbly stands and a drill.
Nope
@@DadBuilds When you get older, you'll learn not to get butt hunt when your suggestion is rejected. : )
He is right. Its his boat and project. He can do whatever he wants. No ill from here.
I think I would add anti-rattle washers on that prop end cap or something to make sure those bolts don’t come loose.
One of the most informative videos to date. Thanks Doug
How you guys resisted the urge to toss an onion or something into that spinning prop is supernatural.
Fun vid.
hey seeker and co happy new year. my knowledge on marine shafting is minuscule ..keith fenner knows and is probably a good resource for you to make use of..
Bravo. You guys are nuts 😂
I first saw your channel when you where casting the blades with kay.
Its been a great adventure since then.
When it’s on the stand without power, whichever prop rotates toward the ground is the heavy one
That is the minimum what he could do.
I believe he did that after casting the blades
While this is true, the heaviest one could also have the most weight at the base of the blade. It turns out that the distance from the point of rotation actually plays a large role in how things balance as well as weight. It's called moment of inertia if you want to read more about it. In short, it's important that the center of mass is the middle of the shaft for the assembly. Or, the same distance from the base on each blade.
@@Akya2120 Center of mass distance from the point of rotation is the only thing what matters = moment of inertia. It does not matter if the heaviest one have the most weight at the base of the blade.
@@deadslow201 it actually does the moment of inertial is some constant times mass times the square of the radius from the axis of rotation. Literally the distance at which the mass is located from the center is exponentially more important. As I said, while getting them to all weigh the same is important, getting the mass to be evenly distributed is more important.
Doug, I haven’t noticed if you had already done this or if it’s even possible but what about putting a large ball valve on the propeller shaft tube just in case you had to pull the shaft completely out while in the water or while seeker is on her keels and the repair takes more than a day and the tide will come up again... you usually think of everything and have a plan, but this just popped in my head. Thanks for sharing.
Edit: I even had an afterthought for just a big rubber plug lol just in case you had the cutlass bearing out. Paint the plug red and keep it with your puller.
To test the blade balance, using your CNC capabilities, make a "jig" that would allow all three blades to be mounted, at 120 degree separation, with a pilot hole of about 3 inches in the middle. Once the jig is finely balanced, mount the blades and set all the angles the same. Then mount the whole contraption onto an automotive "bubble" balancer. The position of the bubble would give you the heavy incidence and you could adjust accordingly.
hes deffinately a friend everyone needs this dude denied help and offered tacos what a fucking legend go get yall some friends like him
RC model airplane builders use a similar rig to balance their props. The heavy blade always stops at the bottom. Remove a little material from the heavy blade. When the prop stops in random locations when given a push its in balance. This works fine for rc motors spinning at thousands of rpms. You may want to use bigger rollers like bicycle tires to make it more sensitive. Offset the wheels so the shaft contacts on the upper half of the wheel circumference. You wont be spinning the prop fast at all in this rig just a push by hand to get it moving. The prop will act like a pendulum.
Long time viewer, first time caller.
This is scary to me - and it's the first of your videos where I really feel that way - I generally agree with your stance on safety. I think there's a risk here you didn't account for - if it fell off the stand the prop would, as you say, go north. But when that happens, the shaft would rotate around it's center of mass, sending it's other end south - into you, holding the rpm meter. Even if I'm wrong about all that, the amount of kinetic energy there is over the top. I wouldn't want to be anywhere near it.
If you can’t figure out where you should stand then you should not be around. :)
I hope I get to see Seeker and Tallyho sailing together one day :)
I would go where that happens. 100 year old English rebuild next to an American build Chinese junk ship from OK. Both re/built in America. Love it, please post the meeting location.
I think I just found my new favorite channel!!!
Your right on track with the balancing of the props and I think the vibration was coming from the tale end of the shaft not being supported do to gravity pulling down on the end while rotating... just a thought thou!!!
Luv what your doing!!!❤️❤️💪🏼👊🏼👍🏻🤣🤣🤣
I used to ballance C-130 Propellers. Before we had the high tech sensors we ballanced them the same way car tires used to be ballanced. Horizontal on a pin and we added the ballance weights on the hub. Might be worth exploring.
THAT IS REALLY SMOOTH STUFF...
get a piece of chalk, and gently touch it to the front nose while its spinning. the high point (heavy) will leave a mark, place a trial weight on the opposite side and repeat. etc
Can’t wait to see it in the water
Doug i have a 38 foot cape island fishing boat and had a wobble in shaft of the boat it’s not variable pitch but not only did I ruin every bearing and cutless but also the transmission I’m running a 220 John Deere so pretty much the same hp as you think you have a 210 Cummins just a heads up is all I sent my blade out to a foundry in Nova Scotia and they polished and balanced for 400$ fixed everything no problems after it was done
This guy knows his stuff👌
You do great work, but your attitude is even better!
just watched all ten of these fantastic keep up the great work
Wow, this is a great project. I can mostly tell within a minut or so if a vid is gonna bore the pants of me or if the guy that made it knows what their talking about. In your case I kwew within 30 seconds: This guy is smart. Brilliant, thanks.
Now you've got me curious how they balance drive shafts for cars... I suspect having a balanced shaft is important as well as having balanced blades. If you fire up the prop and the whole boat has a resonant frequency, you'll know where it's coming from! Hell, that might be kind of nice to have a little hum once in awhile. Top shelf Doug!!!
They spin them on a balancer like everything modern these days and apply weight or remove weight as necessary. Local shop in Georgia charges $120 to shorten and rebalance shafts.
Think Tacoma Narrows Bridge Collapse - when the vibrations for a given structure resonates to the point where the amplitude begins to increase continuously to the point of destruction. This typically occurs when the natural frequency of the support structure and the rotating vibration ( inducing force) (wind in Tacoma Narrows case), excites the structure, growing in strength.
There is such a thing as a critical speed and machinery should avoid lingering at or around this rpm. Move the throttle quickly past this point when speeding up or slowing down. As stated by many commenters vibration reduces bearing life, the lower the better.
I That said your test rig set up did actually depict the bearing support configuration found when in the vessel so it likely you won’t see the vibrations at the same rpm or at all. My suggest is to get the weight as close as possible in a static condition and call it good.
perfect doug. i was about too comment on balancing on CM. thumbs up buddy!
and when i first started watching your channel , you were casting the propellers and now you have a wet date, tks for sharing the journey ,
love ya man, life is not perfect but it works if you try. Keep pushing the more you learn the less you realize you know.
Sweet been looking at Westsail 42 it has adjustable prop that is controlled by RPM. Been watching since the sub days.
I don't know if you look at comments from videos five months ago but I didn't remember this until the blade started spinning on that stands that you had but I just wanted a comment that one of my favorite sounds in the whole world is that sound of the grease going squishing pop and it's like you can't really describe the noise you have to make it and the best way to do it is with the s*** ton of Grease ciao for now
Vibration can carry through the boat and rattle things apart I think it’s very important to make sure that you have perfect balance.
If you place it on a on a truck rim you can get a static balance with a bubble level.
I would mark with a punch the center of gravity on those blades now while your out of the water just a suggestion. It was pretty impressive to see six hundred rpm on that setup! pretty cool it was moving. Happy New Year Doug.
Talk to an AME. A prop balancer will work. Also, that 120 grams will make a significant difference on your bearing life!!! I would start with static balance (blade weights) then finish off the dynamic balance with an aircraft prop balance.
You guys continue to set the bar for playing things fast and loose, pun intended! I understand just leaving the shaft lay in the bearing but I would have thrown a few sandbags on both of those uprights as an insurance policy. I know you don't care much about the safety aspect but that's a lot of work to redo if that thing comes apart.
Damn! It’s great to see savvy back yard mechanics doing stuff with a combination of low tech, high tech and common sense. That’s a recipe for innovation and adventure.
Run the shaft without the blades then see if it vibrates.
As a helo pilot you are really trying to get something difficult done. Congratulations on the progress!
Dewalt for the win..... Very impressive shaft
Hello again Doug, Have you ever driven a car with a drive shaft that was out of balance. Try balancing the shaft with no propeller.
4:02 doesn't make it any better