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  1. #1
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    Default The outrigger and proa thread

    Here it is: a thread for those building wooden outriggers and proas!

    Please post builds, questions, sailing pics, etc.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    Here it is: a thread for those building wooden outriggers and proas!

    Please post builds, questions, sailing pics, etc.
    Good to see. Here's mine:

    Ulua stretched to 21'
    http://wikiproa.pbworks.com/w/page/1...s-21'-Ulua
    Tamanu as a catamaran
    http://wikiproa.pbworks.com/w/page/1...xas-200-report

    Having a tough time inserting pics today.

    Dan

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    Default Re: The outrigger and proa thread

    Here's mine so far:

    I'm building Gary Dierking's Wa'apa sailing outrigger canoe. It disassembles into 8' long sections. I modified mine a bit though (dierking is one of the rare designers who actually encourages modifications/experimentation with his designs). Mine will be 20' long instead of 24', for building space/ cartopping reasons. So the center section is only 4' long. Still plenty of boat, as I discovered when I laid the unfinished hull out in my livingroom this weekend!



    I also am building a modified ama. I figure the original ama, while good for paddling, has very little flotation. I have seen people standing on the amas of their canoes, and loading up their outriggers on the trampolines, so a larger ama can come in handy. Plus what better place to hang out while sailing than a well supported trampoline? I kept a high waterline/beam ratio, higher than the hull, but still have a total of 400lbs of displacement according to my rough calculations before the ama gets submerged.





    (sorry for the low quality pics, low light plus cell phone camera)...

    The other thing I am doing was based partly on the inspiration of Dan's double tamanu project. I have built a second hull, which will only be used in a catamaran configuration. The idea is that when I want the ability to have more crew, or to cruise further, I can rig up two hulls as a catamaran and be much more stable and more able to carry crew/supplies, at the cost of overall speed.

    As far as cross beams/rig/foils/steering, although it will be a tacking outrigger/catamaran, I am still undecided about details. I have been in touch with a guy who built a wa'apa in africa that steers using two lugsails only, no rudder. There is also a way of steering with just daggerboards, but my concern is that minute adjustments can't be made quickly that way, and every boat I've ever sailed, including catamarans, has had to be constantly adjusted at the tiller... yet polynesians have been weight/foil steering for millenia, so...

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    Still plenty of boat, as I discovered when I laid the unfinished hull out in my livingroom this weekend!
    that's awesome! sounds like something i'd do (and my wife would shake her head over).

    trevor

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    Default Re: The outrigger and proa thread

    haha well I had to wait for my girlfriend to be out of the house to set it up, to avoid all that eye rolling !!

    But seriously, setting it up full size really gave me and my building partner a feel for the seating arrangement/iako arrangement/mast position/etc., worked so much better than when I just tried to draw them out on paper... also allowed for some daydreaming on a cold winter day

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    haha well I had to wait for my girlfriend to be out of the house to set it up, to avoid all that eye rolling !!

    But seriously, setting it up full size really gave me and my building partner a feel for the seating arrangement/iako arrangement/mast position/etc., worked so much better than when I just tried to draw them out on paper... also allowed for some daydreaming on a cold winter day
    I KNEW as soon as I saw the hull on your living room floor ... you were a bachelor.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    I have been in touch with a guy who built a wa'apa in africa that steers using two lugsails only, no rudder. There is also a way of steering with just daggerboards, but my concern is that minute adjustments can't be made quickly that way, and every boat I've ever sailed, including catamarans, has had to be constantly adjusted at the tiller...
    I was in touch with Chris (the guy from Africa). He will be away for the next few months, but here is what he e-mailed me about the weight/daggerboard/sheet steering concerns I had:

    "I read your concerns about steering. Don't worry about that too much. YOur probably not going to race around buoys anyway! Just keep a paddle handy for emergency turns. Paddle steering is very convenient. You can sit just about anywhere on the boat and control it. If you use some power paddling techniques to control the boat you will add a lot to boat speed from steering instead of slowing it down. If you keep a few paddles laying around the boat in stragegic locations you don't have to worry about running into anything. Most sailors oversteer thier boats. Everytime you move the tiller you are putting on the brakes! Most beach cat sailors sail with the rig out of balance, so they have to use the tiller always with some weather helm or lee helm. If they let go of the tiller for an instant the boat will swing into or off the wind. Once you are sailing on course using the boat dynamics to steer the boat the boat will change course when the wind changes direction, course corrections are easy to accomplish when you are familiar with your rig. Just lift a leeboard a little or haul in on a sheet a few inches. Also, the Waapa tracks like a freight train! Very little rocker and those long chines make it stable on course. You'll feel that when you paddle to the dock using some draw strokes!"


    He has actually built a rudderless Wa'apa so his advice is pretty reliable in my book... interesting too...

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    Default Re: The outrigger and proa thread

    i bet the small ones had a steering paddle, and the big ones had lots of time for adjustment.

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    Default Re: The outrigger and proa thread

    I've just got a few rough proa/outrigger models built so far, but started cutting on my full-size Wa'apa build a few weeks ago. After I get the use of my father-in-law's table saw this Friday evening for chines and gunwales, the main hull should go 3D next week sometime. (In theory. Hard to commit with a two-year-old in the house.)

    Wa'apa


    3M Proa, nearly built to get under Missouri's 12' boat licensing restrictions.


    Heavily modified 3M Proa, converted to Imperial and stretched to 12' and made tacking. With a more positively buoyant ama. Abandoned when my wife decided she'd like to come sailing with me in the spring.


    My 16' Wa'apa build can be followed here, but I'll try and post anything of significance to this thread. Hopefully I won't get too abused for using SurePly and giving it a rough workboat finish.
    http://www.flickr.com/photos/1223521...7625305053212/

    Trevor

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by trefor View Post
    My 16' Wa'apa build can be followed here, but I'll try and post anything of significance to this thread. Hopefully I won't get too abused for using SurePly and giving it a rough workboat finish.
    http://www.flickr.com/photos/1223521...7625305053212/

    Trevor
    Looking forward to the updates. My thoughts on appearances were that the boat is there to be used, while excellent craftsmanship is always appreciated its only going to matter at a boat show. And the extra time and materials you spend on getting that perfect result could be spent on the water with the family.

    On the topic of time management, in reflection I could have used my time a lot better. There is quite a bit of down time with glue/epoxy/paint drying that could have been used working on the smaller perferal jobs. So try and look at the project as a whole and plan to get the best out of your limited time.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by basm View Post
    Looking forward to the updates. My thoughts on appearances were that the boat is there to be used, while excellent craftsmanship is always appreciated its only going to matter at a boat show. And the extra time and materials you spend on getting that perfect result could be spent on the water with the family.
    i do love a pretty boat and would be like a kid in a candy store at a wooden boat show, but i don't care if i personally own one or not. if at a show, i'd probably marvel over all the brightwork and craftsmanship, but then really drool over the beat-up and rusted working sharpie someone had way back in a corner somewhere.

    building for me is mostly a means to an end. decent small production sailboats are pretty scarce in the US midwest. i might have been able to find an affordable sunfish or hobie cat languishing in a backyard somewhere nearby, but for the price of buying one and fixing it, i could just go ahead and build something that would suit my needs better. if it only lasts a few years, no big deal. i get to build something new, when it does finally give out.

    looking forward to some sailing pics of your ulua. it's really an elegant design. any thoughts on sail color? are you going to leave the boat bright or paint it?

    trevor

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by trefor View Post
    looking forward to some sailing pics of your ulua. it's really an elegant design. any thoughts on sail color? are you going to leave the boat bright or paint it?
    I've painted the plywood fore and aft decks white and will give the gunwales below that red trim, the rest of the hull has been varnished inside & out, the ama will be white (drying in the garage right now) and Gary has made me a red sail.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by basm View Post
    I've painted the plywood fore and aft decks white and will give the gunwales below that red trim, the rest of the hull has been varnished inside & out, the ama will be white (drying in the garage right now) and Gary has made me a red sail.
    sounds nice! especially the red sail. that should look great.

    trevor

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    Default Re: The outrigger and proa thread

    My kayak to sailing tri-yak conversion is underway. Hope to have it in the water by spring:



    Something tells me I'm really going to have fun with this. Gary D's Wa'apa 24 could be in our future, too.
    Last edited by JimD; 12-13-2010 at 11:45 AM.

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    Default Re: The outrigger and proa thread

    Jim,

    You have to carefully observe that the weight you consume with your outrigger adaptation (to include the amas, the akas and the fastening system), does not overwhelm the load carrying capability of your original kayak hull. You probably already know this, but add your kayak weight, to the outrigger system (with sail rig) weight along with your own body weight (ready to paddle/sail) and any stuff you plan to carry. If that complete package exceeds your kayak's displacement figure, you have overloaded the boat and it will not sail on her lines... making for a sluggish boat that will not achieve its potential under sail, or paddle. Something has to go and it will likely be your body weight first, followed by the gear you'd like to carry in the kayak. Or, should you be lean already and not able to drop any pounds, that poundage will have to come from your intended load, such as extraneous camping gear, stores, et.al.

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    Default Re: The outrigger and proa thread

    I suspect that this thread will quickly turn into free advertising for Gary Dierking not that it isn't merited.

    I'm building his Ulua which is nearly complete, just in time for our summer. It's taken me 44 weeks so far, mostly because of space constraints and needing to balance working on it with family time. I've blogged my progress here: Bas' Ulua Build

    Some photos of the first water trials in mum's pool:


    Now where did I put the assembly instructions?


    Wow! It floats!


    Galley slave on the paddle and The Captain in keeping an eye aft.

    I stretched the hull to 6m which was the maximum I could build in my garage, that seems a lot when looking at the hull but that space shrinks a lot when on the water. I also over built the ama stretching the middle so that I could sit on it without completely sinking it for the same reasons as Peter gave.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by Chris Ostlind View Post
    Jim,

    You have to carefully observe that the weight you consume with your outrigger adaptation (to include the amas, the akas and the fastening system), does not overwhelm the load carrying capability of your original kayak hull. You probably already know this, but add your kayak weight, to the outrigger system (with sail rig) weight along with your own body weight (ready to paddle/sail) and any stuff you plan to carry. If that complete package exceeds your kayak's displacement figure, you have overloaded the boat and it will not sail on her lines... making for a sluggish boat that will not achieve its potential under sail, or paddle. Something has to go and it will likely be your body weight first, followed by the gear you'd like to carry in the kayak. Or, should you be lean already and not able to drop any pounds, that poundage will have to come from your intended load, such as extraneous camping gear, stores, et.al.
    Chris, I weigh about 140#. The kayak is a Shearwater Merganser 17'x22" beam, designed to carry up to about 200#. Also, I've taken the deck off and am adding another strake to increase the depth by about 8". So the main hull will end up being a double chined vee bottom double ender with a waterline beam of close to the 22" kayak beam. I expect it will probably sit somewhere close to the original kayak sheer. Here's me in the kayak. I'm guessing the extra weight will sink it another couple inches or so:



    The line drawing from Shearwater's website:



    The additional side panel I'm adding:





    So while I'm not quite sure how deep it will sit or how badly it will sail it should certainly float safely enough and will get me on the water. Didn't calculate the displacement of the amas, either. But I'd guess around 250# each. Who knows, it might even turn out to be not a bad boat, if only by chance.
    Last edited by JimD; 12-15-2010 at 02:41 PM.

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    Default Re: The outrigger and proa thread

    I'm planning on going with a steering oar, myself. It just seems easier to setup than a rudder/tiller and you can use it to sweep the back end through your tack if need be. But i plan to also have a couple paddles onboard for dead weather and easily approaching a dock/boat takeout point.

    Did the African fellow build a 24' or 16' version? Tacking or shunting? Just curious. For some reason I have it in my head that a shunting version is easier to steer by weight and sheet than a tacking version, but I could have easily made that up.

    Trevor

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    Default Re: The outrigger and proa thread

    Basm,

    I actually sent my wife a link to your blog on Friday, jokingly asking her if she thought her dad would let me float my outrigger in his pool come spring, like you have done.

    Was the foam ama difficult to fashion? What type of foam/styrofoam did you use to make it? I was thinking of going with big box store home insulation, if I decide to build a foam ama over the ply one designed for the Wa'apa.

    Trevor

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    Default Re: The outrigger and proa thread

    Trevor,

    I forgot to ask and just showed up with the canoe

    I used building insulation Styrofoam, the branded type rather than the generic no name type. It was easy enough to work with except that it is very messy creating lots of blue dust! plus you have to be careful that you don't dig into the soft foam suddenly. I gave up on getting a perfect shape in the end as it was just creating too much mess. Getting the nose and stern glassed over was a fidely job too. And the end result is heavier than I expected it would be.

    Bas

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    Default Re: The outrigger and proa thread

    You know Trevor, I have that same idea in my head, but logically I don't see why a tacking or shunting rig would make a difference in that respect... he built the 24' version (google ghanawaapa.blogspot) with a schooner lugsail configuration, shunting version. He swears by the shunting, that it's actually easier than tacking (because light multihulls are notoriously difficult to tack). He steers just with the sheets.

    My idea is to have a tacking rig, just a single lugsail (I have one from another boat may as well use it) but maybe install two leeboards, one forward and one aft. Depending on the point of sail, I could lift or lower them to balance the boat as perfectly as can be done, using the steering paddle for mild corrections. I may even rout out a channel going up and down the leeboards, the width of the leeboard bolt, so that the boards could be raised and lowered like daggerboards, giving even more CLR options but remaining kickup for shallow water and for minor corrections in balance.

    I am wary of steering oars as they can really wear you out. I am wary of rudders if possible because they are always the first things to break and take hours and hours to build/install. I had a tiller break on my cartopper once (right at a knot of course). Pulled up the rudder and used an oar hanging off the side, viking style, to steer. It was strenuous, in moderate winds. Worked quite well, though, just required alot of attention. Then again, on a balanced canoe (the cartopper uses its rudder as part of its lateral plane) it might not be so bad and certainly would be convenient for tacking!

    Basm that ulua looks great! I'm so jealous that it's approaching summer in OZ, here in the US we are experiencing a coooold cooold winter that has just begun :-( This thread may just turn into free advertising for Gary Dierking, but he is one of the few designers out there with practical small outrigger plans! I am still looking for plans for an OC6 type outrigger paddling canoe, for pure hawaiian racing sail/paddle canoes, and others but Dierking seems to be the only one with any plans, especially in wood. If anyone wants to prove me wrong on that please do so!

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    I'm so jealous that it's approaching summer in OZ,
    <Cough> New Zealand <cough>

    Most of Australia doesn't know what winter is

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by peterchech View Post
    This thread may just turn into free advertising for Gary Dierking, but he is one of the few designers out there with practical small outrigger plans! I am still looking for plans for an OC6 type outrigger paddling canoe, for pure hawaiian racing sail/paddle canoes, and others but Dierking seems to be the only one with any plans, especially in wood. If anyone wants to prove me wrong on that please do so!
    I looked for a long time and the only other design for homebuilders short of trying to build from the lines in Canoes of Oceana was the 18 or 24' canoes from Selway Fisher.

    Dan

  24. #24

    Default Re: The outrigger and proa thread

    Hello!! This is Chris the guy with the Waapa in Ghana! I'm back from work finally. I've been eagerly reading all this this string and was very surprised to be reading myself!! That was fun! How is your project going?

    Something I never mentioned to you before when we were discussing the shunting double lug rig was that I built a sloop rigged tacking canoe (16ft "nice canoe") with an inflatable outrigger that also did not have a rudder. I was able to balance the rig and sail with the sheets and adjusting the leeboards. It was what gave me most of the inspiration for the rig on the Waapa. That boat was really a lot of fun and sailed really fast! I still have it. It has a gaff rig with a small fortriangle that I took off of a Klepper.

    Comeing about is pretty easy, if there wasn't enough way to take you straight through the eye then a couple of paddle strokes got you the rest of the way really quick. Steer with the paddle until the rig is balanced. You can adjust course by moving your weight around a little, like leaning over to one side or waving your arms around, scooting forward or aft. What got me started in that direction was that I used to sail my TSL with this rig and one day when I got to the beach I had left the rudder home, so I just went without and discovered that I didn't need it!

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by granitefallscc View Post
    Hello!! This is Chris the guy with the Waapa in Ghana! ...
    --- Chris, what do your fellow Ghanaians think about your outrigger? Are sailing on one of those big lakes, or on the coast? My girlfriend spent 6 weeks in Ghana and she had my request to photograph any wooden boat she saw there. She photographed some of the big dug-out canoes on the coast (I thought they were good candidates for outriggers, but they function well as they are, I guess), a pretty little two-person fishing dug-out on a lake, and some curious kayak-like craft used on that big crater-like lake, built simply out of solid squared-off logs with the ends chain-sawed off into rough angles, from which the fishermen checked their nets, paddling with their hands or a scrap of board in their hands -- but I guess the outrigger never evolved on the west Coast as it did on the east coast. -- Wade

  26. #26

    Default Re: The outrigger and proa thread

    I am sailing on the Volta River below Akosombo dam. Downstream the river becomes a lake again when it comes up against the Kpong dam. The river continues about 80K again after the Kpong dam to the sea. I built the Waapa to sail on the lake above the Akosombo dam which is very large and encompasses a lot of wilderness area, wildlife preserves and forrest preserves. I spent the last trip building the Waapa and making sea trials on the river. I plan some expeditions on the lake next trip. The local boats on the river are single hull canoes built from planks. They are typically around 12 to 18 ft. The large fishing canoes used in the sea are dugouts made from huge logs and some chine planks fastened to them. They range from 20 to 40 foot with a few larger. The seaboats use a large square downwind sail to return to the beach after fishing. The trade winds are very dependable. They mostly use a small outboard to go to weather though quite a few of them still paddle. They are very brave seamen as they go over the horizon and spend days at sea fishing. On the river the boats are universally paddled with a round primitive paddle. You rarely hear a motor. They are strong paddlers though the native paddles don't allow for any sophisticated paddling techniques. They are a heavy carved plank with a round blade. On Volta Lake the boats are the plank built kind, generally a little larger than the river canoes but not by much. A downwind sail is used on the lake and the river but it is just an unshaped square sail held up with a couple of sticks of bamboo. When I'm sailing around I know they are watching me very closely but they don't want me to notice. Going to weather under sail has to be very interesting to them. The wood they use to build the plank canoes is very dense and sinks, so if a canoe is swamped the canoe goes under. Some people perish every year from this problem. Ocasionally I'll be sailing to weather and pass some guys paddling, that's when I get some real attention. If I'm paddling when there's no wind they will alway speed up to show me they are faster. The boats are a good design and go pretty fast under paddle power even tho they have no paint and the finish is pretty rough.

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    Default Re: The outrigger and proa thread

    Quote Originally Posted by granitefallscc View Post
    ...The large fishing canoes used in the sea are dugouts made from huge logs and some chine planks fastened to them. They range from 20 to 40 foot with a few larger. The seaboats use a large square downwind sail to return to the beach after fishing. The trade winds are very dependable. They mostly use a small outboard to go to weather though quite a few of them still paddle. ...
    --- Thanks for that information. I have several photos of the sea boats, including one beautifully dynamic one of dozensof fishermen preparing their boats for sea, but the photo showed not a single paddle, outboard, or sail. I figured they must have the outboards stowed away safely somewhere (since I saw some side-planks rigged out to take what I assumed was an outboard), or that the fishermen kept their paddles under cover somewhere. Many of the boats seemed to have small masts, though usually they were flying only a small flag. The adz work on the hulls was interesing -- long vertical scoops that looked decorative but would have vastly slowed the hulls in water, I should think. Perhaps that was part of a ritualistic belief. The painting and slogans drawn on the hulls are fascinating, and for these I did find a good article on line that discussed them. My girlfriend while in Accra saw many commerical vehicles and businesses with religious slogans combined with advertisements, such as "Praise the Lord Plumbing," and "Only God is Our Salvation Hardware Supply." I belief some of the boats had similar slogans painted or carved on their hulls. The photo of the slender lake canoes was too long distance for such details to be seen. Your comment about the sinking wood is fascinating. -- Wade

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    Default Re: The outrigger and proa thread

    I've enjoyed following Gary Dierking's blog site about the development of his new boat. I notice today that the new hull:

    Has a similar shape to a New England Sharpie:

  29. #29

    Default Re: The outrigger and proa thread

    did this work? I am trying to figure out how to post an image.

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    Default Re: The outrigger and proa thread

    Try an image hosting site and then right click the image. Copy the url that ends in .jpg and click the little image button above the reply. Paste the url and uncheck the little box on that page. Or you can email it to me and I'll do it for you--pm me if you'd rather do that.

    Dan

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    Default Leeboard Leverage?

    The spec'd attachement for Ulua's leeboard is through the gunwales and a piece of alu angle screwed to the inboard gunwale and the front seat.

    I have no doubt that this works bco all the successful implementations.

    But under port tack, four feet of leeboard leverage on about one inch of gunwale/alu is generating a certain amount of cognitive dissonance in what's left of my mind.

    I have seen a clamp-on implementation (http://tinyurl.com/89quphl) where my vision of the forces/vectors makes sense: the force is going through the bolt and trying to push the horizontal crossmember down instead of trying to twist the gunwales off.

    Seems like either there's a lot less pressure than I think trying to rip that leeboard off the boat on port tack or my notion of the forces/vectors is flawed in some other way.

    Would anybody care to comment?
    Last edited by PeteCress; 12-25-2011 at 09:59 AM.

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    Default Re: Leeboard Leverage?

    Quote Originally Posted by PeteCress View Post
    The spec'd attachement for Ulua's leeboard is through the gunwales and a piece of alu angle screwed to the inboard gunwale and the front seat.

    I have no doubt that this works bco all the successful implementations.

    But under port tack, four feet of leeboard leverage on about one inch of gunwale/alu is generating a certain amount of cognitive dissonance in what's left of my mind.

    I have sees a clamp-on implementation (http://tinyurl.com/89quphl) where my vision of the forces/vectors makes sense: the force is going through the bolt and trying to push the horizontal crossmember down instead of trying to twist the gunwales off.

    Seems like either there's a lot less pressure than I think trying to rip that leeboard off the boat on port tack or my notion of the forces/vectors is flawed in some other way.

    Would anybody care to comment?

    The aluminum angle should be 1/4" thick. If it is I doubt that you'll ever bend it or damage the gunwale. I haven't had any reported failures yet.
    You can also extend the aluminum further forward and have alternate leeboard mounting holes.

  33. #33
    Join Date
    Aug 2011
    Location
    USA: Paoli, Pennsylvania
    Posts
    747

    Default Re: Leeboard Leverage?

    Now I see that the implementation on my Ulua differs from the spec'd.

    On the spec'd, the top of the leeboard is pushing against the gunwale and the bolt, passing under the gunwale, is pushing down on to the seat.

    On mine, the hole is drilled through the gunwale instead of below it: http://tinyurl.com/7r94wz7

    Same forces, I guess, but the leverage is different bco the shorter distance from bolt to top of gunwale and the bolt is trying to twist the gunwale instead of pushing against it.

    Looks like it didn't work out for some reason bc there are two after-the-fact holes drilled lower in the hull: http://tinyurl.com/728e78q and a plywood re-enforcement inside the hull: http://tinyurl.com/83zs5es



    But none of this addresses my real question. I know it all works bco the experience of others.

    The real question was about how much force there is on a leeboard: it seems like there must be less force than I intuit.

  34. #34
    Join Date
    Nov 2004
    Location
    St. Charles, IL
    Posts
    1,139

    Default Re: Leeboard Leverage?

    Quote Originally Posted by PeteCress View Post
    Now I see that the implementation on my Ulua differs from the spec'd.

    On the spec'd, the top of the leeboard is pushing against the gunwale and the bolt, passing under the gunwale, is pushing down on to the seat.

    On mine, the hole is drilled through the gunwale instead of below it: http://tinyurl.com/7r94wz7

    Same forces, I guess, but the leverage is different bco the shorter distance from bolt to top of gunwale and the bolt is trying to twist the gunwale instead of pushing against it.

    Looks like it didn't work out for some reason bc there are two after-the-fact holes drilled lower in the hull: http://tinyurl.com/728e78q and a plywood re-enforcement inside the hull: http://tinyurl.com/83zs5es



    But none of this addresses my real question. I know it all works bco the experience of others.

    The real question was about how much force there is on a leeboard: it seems like there must be less force than I intuit.
    Use the hole BELOW the seat! I tried the hole in the gunnel not realizing what it would do--essentially twist it off! There's an aluminum angle iron that the bolt head must go through or you'll break the vaka.

    Dan

  35. #35
    Join Date
    Aug 2011
    Posts
    14

    Default Re: Leeboard Leverage?

    Oh hey, that is my clamp-on lee-board. I was not trying to solve any problem by using it. It was vestigial from when I sailed an Old Town canoe. I got it off the aca rig plan. http://www.enter.net/~skimmer/building/building.html

    Happy Holidays to all...

    Quote Originally Posted by PeteCress View Post
    The spec'd attachement for Ulua's leeboard is through the gunwales and a piece of alu angle screwed to the inboard gunwale and the front seat.

    I have no doubt that this works bco all the successful implementations.

    But under port tack, four feet of leeboard leverage on about one inch of gunwale/alu is generating a certain amount of cognitive dissonance in what's left of my mind.

    I have seen a clamp-on implementation (http://tinyurl.com/89quphl) where my vision of the forces/vectors makes sense: the force is going through the bolt and trying to push the horizontal crossmember down instead of trying to twist the gunwales off.

    Seems like either there's a lot less pressure than I think trying to rip that leeboard off the boat on port tack or my notion of the forces/vectors is flawed in some other way.

    Would anybody care to comment?

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