simple amas for canoe-tri

Discussion in 'Multihulls' started by Owly, Jan 4, 2019.

  1. Owly
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    Owly Junior Member

    I'm planning to build a pair of 12' long amas for a canoe tri using cheap 3 ply fir marine ply. They will each consist of two sides, which will be stacked atop each other, joined along the keel and bow, and then opened up, propped open, and bulkheads fitted inside. I have a kind of crazy idea of buying some 2" dia fiberglass sleeve material, which comes folded flat, slicing it down one side, slipping it over the joint while the side is stacked, epoxy gluing it to each side piece, being careful not to get epoxy along the center. This will serve like a hinge as in stitch and glue. Fiberglass doesn't like to conform to corners, but this stuff is sold flat. The inside will be filleted and taped, and the outside taped. The top surface will have one plywood section for a step, the rest covered with doped aircraft fabric with stringers as needed for shape.

    The canoe tri itself will have two side decks built between the akas, resulting in a rectangular area across the boat of 78" fore and aft by 72" across, recessed into the sides a bit. These side decks will provide a seating area & camping area under a boom tent. The amas and outboard akas will extend outward for a total beam of over 10' and be designed to fold up over and inward for transport at only 6' wide by 15' long.
    At night, the central area of the original canoe will have netting stretched over it for a bed. The actual sailing rig will be a cambered junk rig made from very light fabric, considerably over size for the boat due to the instant reefing possible with such a rig. Leeboards will be fitted so they are under the side decks when folded up.

    This is intended to be used for sailing some of the large fairly remote local reservoirs, and camping out. I'm building this from a wrecked canoe... I loaned it out and it came back wrecked ;-(

    H.W.
     
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  2. Doug Lord
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    Doug Lord Flight Ready

    I like the basic idea. It would be nice to see some sketches and to get an idea of the projected ama freeboard. Good Luck!

    PS- about 40 years ago in my 20's my Dad loaned out the family Dyer Dhow to an architect next door. He towed it behind his charter boat ,got in a storm and that was the end . It was the boat I learned to sail in-very sad.....
     
  3. Owly
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    Owly Junior Member

    There will not be a lot of freeboard.... I plan to make these from a single sheet of plywood, so that means 8" sides. I'll use a second sheet for msc stuff like the side decks, but straps, and various other parts. The internal bulkheads will be blue XPS insulation foam, with "plank" glued to the top edge for the beams, and foam knees at gunnel level tying them in more to the sides.... needless to say I will use epoxy and fiberglass to tab things together.

    I have a bad habit of not drawing things out..... I formulate the shape and construction in my head and go, with a few "napkin sketches". I've been doing some cardboard models. Needless to say, there will be significant sheer due to the spreading of the sides. I expect the displacement to be something in excess of 150 lbs per ama. I don't know if that's enough, but it's a good starting place I think. As the amas will fold over, I'm considering making them adjustable in the down position to get the optimal balance when loaded of both just barely making a wake when level... It'll never be level. This would also make it possible to lower both for camping to reduce rocking at anchor. If that makes sense.
    I've been making cardboard models on my desk........I may crown the decks a bit to bump the displacement up to around 200 pounds submerged. I'm sorely tempted to make them just a bit larger displacement such that they will support the average man standing on the deck without submerging, but that means a taller V or a chine, more work or material.... I'd like to keep them small. The marine ply I'm looking at is only $50 a sheet locally. Because I will be able to "hike out" on the side deck, the additional displacement really is unneeded for sailing. The temptation to build more and heavier is something to be resisted I think. As it is 1/4" fir ply is probably over built. 23 pounds approximately per sheet.... not too outrageous if I resist things like adding fiberglass, etc, where it isn't needed.

    H.W.
     
  4. tspeer
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    tspeer Senior Member

  5. guzzis3
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    guzzis3 Senior Member

    Have you got Garry Dierking's Building outrigger canoes?

    Seriously it's one of the best books on multihulls sailboats I've ever read, and he has a design for floats very similar to what you are doing. Lots and lots of good ideas that would not have occurred to me.
     
  6. Owly
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    Owly Junior Member

    A bit of googling yields many variants. I am perhaps being too conservative in beam over all and also in displacement of the amas. A number of designs use hulls built the way I'm doing my models. I found a page of Michael Storer designs showing a "napkin drawing" similar to what I've been playing with, however he has a raised canoe type bow, where I was not planning to do this. In the drawing the stern is simply stitched together..... as I did one version, but the desire for a bit more displacement makes a transom more desirable. I think 12 foot amas on a 15 foot canoe make some degree of sense..... at least in based on TLAR "engineering" (that looks about right). I do not intend to spend hundreds of dollars on plans. Richard uses a V bottom and chines on his amas, based on the study plan. I've considered exactly this, but it's more hull panels, more material, and more joints. This is supposed to be a pretty simple project. Richard Woods Strike 15 is a lovely little tri along the same lines but built specifically as a trimaran, and well worth the price of 95GBP, but I'm simply looking to put together a cheap canoe tri from a broken canoe, with minimal investment of time and dollars. It doesn't have to be a performance boat, the purpose is to explore and camp out. I want to be able to put up a lot of sail area for the size boat so I can ghost along in light winds, rather than kicking ***. The temptation is to use 12" sides instead of 8" sides, which would greatly increase ama displacement (over 300 lbs each) to the point where you could probably fly the hull at times, depending on the over all beam, but that is more weight, and more structure needed, which in turn is more weight yet. Every aspect of something like this is a judgment call. I ask myself "what's the mission", and I fall back to my original plan. It's not meant for "big water". The mission is to enjoy sailing the remote reaches of the big local reservoirs, camp out, and explore, and to pursue my interest in the modern cambered junk rig. The quick and dirty solution of course is just to use plastic pipe, but I find that not at all appealing..... I'd much rather build hulls. A V hull averaging 10 inches in all three dimensions would be 50 square inches cross section. An 8" diameter pipe would have almost the identical displacement........ and zero appeal...... and probably too much longitudinal flex.

    H.W.
     
  7. redreuben
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    redreuben redreuben

  8. fallguy
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    fallguy Senior Member

    I build amas and akas for my canoe and a sail. The amas and akas are basically anti-tip rigs, but would probably work in light winds. I built a sail and started, never finished lee boards if you wanted to tack, nor did I build a step to use the mast.

    They are based on a silly book and the amas and akas are based on Gary Dierking's designs. The amas and akas are not silly at all. The boat never ran under sail and probably never will.

    The $50, 5 Hour Canoe Sail Rig: by William Mantis - Small Craft Advisor http://smallcraftadvisor.com/the-50-5-hour-canoe-sail-rig-by-william-mantis.html

    You could have the sail if you are close to Minnesota. Mom sewed it from some rip stop or tougher nylon.

    I would recommend using xps for the amas and making akas from a veneered layup of some sort. The hardware is all various sizes of pvc with pins. The amas have two positions for loaded canoe or unloaded canoe. We realized this need in tests. Yes, there is ice on the lake.

    4461A1A1-87CC-4D22-98A4-7FA76F02B582.jpeg
     
  9. guzzis3
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    guzzis3 Senior Member

    The books is $21 on amazon a few $ more on ebay. It contains everything you need to construct 2 types of floats a diamond section plywood version and a rounded float. He offers several ways to connect, several beams and a couple of main hulls. He also gives details of various rigs, tacking and shunting.

    It is a superb investment even if you never build one. The problems with boatbuilding of any sort are all too often in the details. GD's book is full of details like mounting a lee board, building an outboard bracket. It has fantastic advice on materials and the details of building. It is practical down to earth and open minded regarding your choices and preferences. He is clear precise and complete with his explanations.

    It is a great book.

    https://www.amazon.com/Building-Out...ilding Outrigger Sailing Canoes Gary Dierking
     
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  10. fallguy
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    fallguy Senior Member

    Yes. I would never venture to do what Owly wants to do without reading Dierking. Dierking's website abilities are sorely lacking, all the reason to like him more. I attached my akas with rubber inner tube lashings from an old tire tube I got from a farmer friend. Not sure if I got it from Dierking; but likely.

    A second vote for that Strike from Wood's. I'm biased.. It makes the canoe and outriggers a little silly in comparison, though.
     
  11. Owly
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    Owly Junior Member

    Lots of good ideas here. The amas I see such as the Chesapeake ones are as one person described them "anti tip devices". My project has a mission that makes far large amas in relation to the boat more desirable.... or at least it seems that way to me. Remember that the actual canoe once the mods have been done to it will be vaguely similar to Richard Woods Strike 16 in that it will have wing decks incorporated into the hull and beams, though it will be smaller and lighter, and based on a fiberglass canoe hull. The side decks will give a seating area, as well as making it a viable "camper" for overnight trips. The Strike was not the inspiration, but as close to being what I envision as I could find. Even the wind screen bears some resemblance to what I had in mind for a spray deflector. His boom tent... a sort of wall tent, is also very much like what I had in mind. The amas are considerably larger than I had planned, as is the beam. What I have in mind is significantly smaller and lighter. If I were plans building, instead of putting something together from what I already have...... trying to do it with a low cost in materials and labor, I'd probably build his Strike 18, which has a usable cuddy. As it is, this will be a minimalist sort of project. Note that Richard uses beach cat hulls for amas, and they are probably a bit more than necessary.
    As it is, I will not be buying anybody's plans... a book perhaps, but nobody's plans fit my criteria. The finished boat will not resemble a canoe with floats very much. It will be decked forward of the front beam (Aka), and aft of the aft beam, creating sealed compartments to contain camping gear. The wings will be about 6'6" fore and aft by approximately 18" outboard.... the canoe of course is curved so this will not be constant. They will be taped right into the sides of the canoe, and all around. Interestingly, in one of the links in a recent post, the author talked about making the floats on his canoe two position.... one for at rest and one for when on the go.... This is exactly the situation I had anticipated.




    Strike 16 Trimaran for Sale | Small Trimarans http://smalltrimarans.com/blog/strike-16-trimaran-for-sale-2/
    [​IMG]
     
  12. redreuben
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    redreuben redreuben

    Owly have a look at the small Scarab Tris, the plans are cheap as.
    You can adapt as required the 16’ is currently the monthly special for $100.00 Au.
     
  13. Doug Lord
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    Doug Lord Flight Ready

    ==========================
    red, did you see this?



    Strike 16 Trimaran for Sale | Small Trimarans http://smalltrimarans.com/blog/strike-16-trimaran-for-sale-2/
    [​IMG]
     
  14. guzzis3
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    guzzis3 Senior Member

    Obviously it depends on what you want to end up with.

    The scarab 16 requires quite a lot of materials for it's size. The skin area is about 70% of the 25' cat I'm hoping to build. I know someone who is building one and I really like the design but...

    Hulua's main hull is only about 7 sqm of materials. The ply boat would be extremely fast to build until you get bogged down as always in the details as usual. A canoe is typically closer to 3' wide. It would not be my first choice for a trimaran hull, just as beach cat hulls would not be my first choice for floats.

    GD puts his work into longer waterlines which makes a lot of sense. Super fine super long hulls supported by elegant floats. Really small rigs 7 - 9 sqm most of them. When your hull is 18" wide it doesn't take much to drive it, and of course a 2hp outboard will be more than enough.

    If you want accommodation then tramps and tents make a lot of sense. RW's 18' cat for example does something REALLY sensible. You sleep etc under a boom tent and the little cabin is just for potty and galley. It gets to a point where cabins on small boats become oppressively claustrophobic as soon as you are in, so it makes sense to use demountable accommodation.

    Just some thoughts.
     

  15. Owly
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    Owly Junior Member

    Everybody has great ideas......... for me to do.... ;-). Great projects. The truth is that I'm lining things out for a very large boat project I plan to begin in about a year and a half... Large that is in comparison to these. I have a semi wrecked canoe that I can repair easily, and simply want to put this together for fairly minimal cost and labor.... I probably will only use it for a few years when I want to get away for a day or two. I of course check all these out for ideas. The Scarab (just mentioned) with it's nice little cuddy looks like a fun boat, but it's far more of a project than I want at the moment...... I like his sensibly long slender amas.
    Most of these kinds of amas have a chine, which to me is just more complexity... though it may be necessary. My original thought of the V hull is based on utter simplicity. Each hull consists primarily of two pieces of plywood joined at the keel and bow with a couple of bulkheads and a transom. A portion of the deck will be ply for a step, the rest simply doped fabric over some stringers... cheap heat shrink 1.8 oz glider fabric with Randolph dope. The ama hulls will not be glassed beyond the seam taping and tabbing necessary. The mast will be free standing, perhaps wood or aluminum, so a cuddy like the Scarab with it's stayed mast is completely out. This will go together for just a few hundred dollars, and not a lot of time. Issues like shelter in those sudden summer storms will have to be dealt with as they would in an open canoe... head for shore or a sheltered anchorage and throw up the boom tent until it passes. Other issues like having some sort of head, will need to be creatively solved.... as they would be in a canoe.
    The problem with any small project like this is the tendency for "leeway"..... drifting off course from the original intent under the well intentioned "cross winds" throw up when you make it public and invite comment and ideas. They are all welcome, but I have my centerboard well down, and the rudder lashed........ I learned that long ago. We've all been there I suspect.
    H.W.
     
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