My sons proa the Slight return has a removable rudder each end that is side mounted on a vertical pintle to windward side of the main hull. It works well & is simple & strong. If you are working a proa anywhere where there are other boats & congestion you need it! Spade rudders are good at low angles but stall quickly at high angles of attack.
Wow, this is the first time I see a proa with a spade rudder! every other proa I can think of has a kickup or at least retractable design. That said, I see that spade rudders are surprising common on production crusing cats (I currently have my cat hauled out in a boat yard along side a lot of large production cats so I have been able to sample the design field) it really seems strange to me because I consider being able to get up to the beach or into shallow water a very significant advantage of a multihull - although, I live somewhere with a large tide range and if your are sailing mostly in the Mediterranean or the Baltic that might be acceptable... but to me I look at them and see that if you ran aground you could do serious damage to the rudder or the propeller.
The 'New Age of Sail' guys in Hawaii seem to be playing with reversible interlinked spade rudders. I'm 100% with you on being able to park on the beach. But I interpreted the video as "this is a quick test, I plan to implement Newick/Brown/Harris style retractable ones" Lot easier to stick a tube through the hull than build a cassette in.
I wonder if there would be some way to have it connected to the sail so that it moves with it from one end to the other. Of course then you would have a bow rudder.
oh yeah, I think the rudders on the John Harris designs are large so you have control at slow speed. Lift (steering power) is proportional to the square of speed so once you are going fast a small rudder is enough!
@@fjordproa6510actually, I just suddenly remember... the real test of a multihull rudder is surfing down waves. When I first become interested in proas in mid 2000s, breaking your rudder was somewhat of a badge of honour on the proa file. I didn't manage to build a successful shunter in that period but I did make a tacking outrigger that took me for a long cruise and I broke the rudder. I've also broken rudders on my cat. usually there is not that much force on the rudder but when you are surfing down a wave it's suddenly significantly more. Speed can quite easily double compared to normal and if you are not going exactly straight you will need to make a hard correction also so the force might be 10 times normal. You need strong wind and a long fetch and to sail downwind to get into those conditions
The CLC boats also have Western rigs on them, so the overall sailplan CE is going to be a long way aft relative to the hull-only CLR (unlike either of your boats). I think that big cassette rudder is doing a lot of lifting work to pull the CLR backwards.
Watching this, I have an idea. Since you normally control the boat by trim, you are just moving the CLR, right? What about.... instead of a rudder, you had basically a daggerboard or leeboard on each end of the hull. The front board would be raised, but the aft board would be raised or lowered, instead of turned. To turn far downwind, the board is extended deep to pull the CLR aft, and to tack upwind, the board is raised to allow the CLR to go forward (and maybe the forward board is dropped just a little to move the CLR forward even more). This "should" turn the boat as well, right?
Hello, this is what they do now on Proas.is. In my Video # 41 ua-cam.com/video/ZMzQ5VLDXKE/v-deo.html from 7:17 and 7:42 you can see that they now have 2 centerboards. But I think they use them more for trimming than for direct steering. Ore ask at www.Proas.is
Sorry for a little unsolicited advice - I would go with separate tie-on fixture for steering with kick-up rudder blade. Shunting rail on your boat makes it a bit tricky to implement though... Tooting my own horn - on my boat, the entire steering is a separate thing that is lashed to the gunwales and the rudder blade is hanging next to the hull. No good video to show it, but here you can get a glimpse after 0:30 mark ua-cam.com/video/gYs4bznSQJ0/v-deo.html
Hello, thanks for the comment. The main reason for my test was to find out how big the rudder blade should be at least. The rudders are made retractable into the hull. This is well-known technology and works well. Look at: clcboats.com/shop/boats/wooden-sailboat-kits/madness-31-foot-pacific-proa.html
My sons proa the Slight return has a removable rudder each end that is side mounted on a vertical pintle to windward side of the main hull. It works well & is simple & strong. If you are working a proa anywhere where there are other boats & congestion you need it! Spade rudders are good at low angles but stall quickly at high angles of attack.
Wow, this is the first time I see a proa with a spade rudder! every other proa I can think of has a kickup or at least retractable design. That said, I see that spade rudders are surprising common on production crusing cats (I currently have my cat hauled out in a boat yard along side a lot of large production cats so I have been able to sample the design field) it really seems strange to me because I consider being able to get up to the beach or into shallow water a very significant advantage of a multihull - although, I live somewhere with a large tide range and if your are sailing mostly in the Mediterranean or the Baltic that might be acceptable... but to me I look at them and see that if you ran aground you could do serious damage to the rudder or the propeller.
The 'New Age of Sail' guys in Hawaii seem to be playing with reversible interlinked spade rudders.
I'm 100% with you on being able to park on the beach.
But I interpreted the video as "this is a quick test, I plan to implement Newick/Brown/Harris style retractable ones"
Lot easier to stick a tube through the hull than build a cassette in.
@@375dash very true, great point
I wonder if there would be some way to have it connected to the sail so that it moves with it from one end to the other. Of course then you would have a bow rudder.
oh yeah, I think the rudders on the John Harris designs are large so you have control at slow speed. Lift (steering power) is proportional to the square of speed so once you are going fast a small rudder is enough!
Yes, good point.
But when I entered the harbour I was very slow and it went well enough.
@@fjordproa6510actually, I just suddenly remember... the real test of a multihull rudder is surfing down waves. When I first become interested in proas in mid 2000s, breaking your rudder was somewhat of a badge of honour on the proa file. I didn't manage to build a successful shunter in that period but I did make a tacking outrigger that took me for a long cruise and I broke the rudder. I've also broken rudders on my cat. usually there is not that much force on the rudder but when you are surfing down a wave it's suddenly significantly more. Speed can quite easily double compared to normal and if you are not going exactly straight you will need to make a hard correction also so the force might be 10 times normal. You need strong wind and a long fetch and to sail downwind to get into those conditions
The CLC boats also have Western rigs on them, so the overall sailplan CE is going to be a long way aft relative to the hull-only CLR (unlike either of your boats).
I think that big cassette rudder is doing a lot of lifting work to pull the CLR backwards.
Watching this, I have an idea. Since you normally control the boat by trim, you are just moving the CLR, right? What about.... instead of a rudder, you had basically a daggerboard or leeboard on each end of the hull. The front board would be raised, but the aft board would be raised or lowered, instead of turned. To turn far downwind, the board is extended deep to pull the CLR aft, and to tack upwind, the board is raised to allow the CLR to go forward (and maybe the forward board is dropped just a little to move the CLR forward even more). This "should" turn the boat as well, right?
Hello, this is what they do now on Proas.is.
In my Video # 41 ua-cam.com/video/ZMzQ5VLDXKE/v-deo.html from 7:17 and 7:42
you can see that they now have 2 centerboards.
But I think they use them more for trimming than for direct steering.
Ore ask at www.Proas.is
Sorry for a little unsolicited advice - I would go with separate tie-on fixture for steering with kick-up rudder blade. Shunting rail on your boat makes it a bit tricky to implement though... Tooting my own horn - on my boat, the entire steering is a separate thing that is lashed to the gunwales and the rudder blade is hanging next to the hull. No good video to show it, but here you can get a glimpse after 0:30 mark ua-cam.com/video/gYs4bznSQJ0/v-deo.html
Hello, thanks for the comment.
The main reason for my test was to find out how big the rudder blade should be at least.
The rudders are made retractable into the hull.
This is well-known technology and works well.
Look at:
clcboats.com/shop/boats/wooden-sailboat-kits/madness-31-foot-pacific-proa.html
Interesting. What do you do with it when shunted so its in the "bow"? The Chesapeake rudders are a cartridge that can be retracted right?
disregard. I see your comment below that you are determining size before building retractable style. Very logical.