I'm new, I want to build a mini trimaran

Discussion in 'Boat Design' started by Willzilla, Dec 3, 2011.

  1. upchurchmr
    Joined: Feb 2011
    Posts: 3,287
    Likes: 259, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Willzilla,

    As far as I can tell the "Drifter" tris in the Duckworks site have all three hulls flat bottomed. You can see how the bottom is curved (has rocker). This will be necessary to get the boat to turn.

    Watson has a very good point, proven plans will actually save you money. I don't think you will make a $100 boat without lots of free stuff.

    I'm building a kayak from someone elses design, my $600 estimate will be $1200 without paddle and seat. Some of the extra has come from my attempts to "improve" the design.

    If you were to build the Drifter with glass and epoxy in just the corners and the outside of the bottom I suspect you would need $100 of epoxy - if you can get 1/2 gallon without paying extra and the same or a little less in glass cloth. I am using US prices, don't know what you have to pay in New Zeland. Several people in the thread are closer to you and would have a better idea.

    I would suggest the 12' Drifter would be about as small as you really want to go, I know smaller has been done, but those boats always seem to be sitting behind the house rotting after a short time. Around here the simple and cheap way to get a sail is to buy a used windsurfer mast and sail. I have not done it but am thinking about it for my kayak.

    I wish I had of tried this at your age.

    Have fun,

    Marc
    PS: Don't worry about all the paragraphs starting with I - you have lots of company. But it is more interesting to find a way to do without the I. But talk is cheap - I ignore my own advise.
     
  2. Willzilla
    Joined: Dec 2011
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: New Zealand

    Willzilla Junior Member

    Resin is out of the picture for now then.. but thats fine! Right now I cant be putting in the money and stuff to do a normal build (which seems silly) but my plan for all this was to make something that sails for fun no matter how good it is. It just needs to be safe of course and I'm trying to figure out the best way for me to achieve that. Maybe if I got a job I could do more! But they are very hard to find.

    Can anyone tell me if this could be rigged to sail? http://www.bateau2.com/free/cheapcanoe.htm

    would it be worth it? I'm happy if it works ok. I'm just trying to find plans for a canoe to use as the main hull and this shouldn't cost toooooo much.

    edit: nevermind it has glass.
     
  3. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    =====================
    You live in one of the greatest sailing areas on earth-would it be worth considering a small used boat?
     
  4. upchurchmr
    Joined: Feb 2011
    Posts: 3,287
    Likes: 259, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Willzilla,

    Your initial request said trimaran, so I got focused on that. If you can find a canoe, the sail area you have has been used many times, without floats. Then you would need to mount a mast, make a leeboard, add a rudder and you could be sailing. There have been many such boats made, historically there were lots. Sorry I don't have a reference, but Howard Rice is a proponent for small (really small) boat crusing. Look here for his comments: http://forum.woodenboat.com/showthread.php?139540-SCAMP-envy-lust/page2 .I know his are much more fancy than you need, it just shows the concept.
    You could also search for his sailing canoe "Slyph" in the same forum.

    Marc
     
  5. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    - those ama-mounted mini-keels make a lot of sense. I notice the amas are mounted high enough that the keels can pass over rocks or allow beaching without damge to the keels.

    The keels need to be firmly attached as they take a lot of force at times. The lumber bottom plank in my sketch would make that easy to do, mount them recessed into slots in the bottom plank with battens along the joint on each side; they can be 3/8" plywood or thicker.

    It’s a flat-bottomed canoe, I didn’t like mine and it soon got cut up and tossed in the trash. It’s easy to build but probably noisy, slow to sail with amas and tippy to paddle without. A flat-bottomed boat needs more beam to feel stable, narrow craft like kayaks have rounded bottoms to ride low in the water which helps the stability.

    Usually the mast is attached to the forward crossbeam, which reacts the wind force directly to the downwind ama. However it will sail best when you use your body weight to balance it so just the keel iin the water; then the wind force will be twisting the hull one way while your body weight twists it the other way. So the hull needs to resist the twisting forces, which the flat-bottomed canoe is not designed to do. This amount of force is unlikely to trouble a commercial fiber-glass canoe which tend to be over-built.
     
  6. kerosene
    Joined: Jul 2006
    Posts: 1,285
    Likes: 203, Points: 63, Legacy Rep: 358
    Location: finland

    kerosene Senior Member

    1 person likes this.
  7. Willzilla
    Joined: Dec 2011
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: New Zealand

    Willzilla Junior Member

    Thanks for all the replies so far

    On the subject of kayaks (I love the tortured plywood one) What sort of performance could you get from one rigged to sail? My dad was saying kayaks cant sail nearly as close to the wind as a sailboat, but I think he's thinking of the much more simple down wind kayak sails. The one I have has a proper mast and boom set up. If I set up a kayak with that and ama's would it be an ok sailor or would it perform poorly?

    Mainly because (same deal with a canoe) if I could de-rig it and use it as a kayak that would be much more functional. My Dad's a kayaker and a sailor and I think he would have a bit of fun.

    Also kayaks don't seem to require as much materials and space compared to most of my other options so far. I wanted this project to be minimal and just for fun mainly, then maybe when I'm a bit older with a bit more money I could do a nice build properly. But right now up sizing a bit becomes too much. the other reason i don't want to spend much is if I had that kind of money to spend then I would be buying more tools and things to be making a bit more money. I'm in the first part of my summer holidays though and I would love to do this as a fun project. And if I managed to build a kayak before I went on holiday in janurary I could take it along and use it! Rigging it to sail wouldnt matter as much at that time. It would be a bit rushed for time though.

    If I worked on a canoe what is the likelihood my setting up a hammock from the front to the back and maybe removing a few seats (if possible) to make it hang lower? That could make for a pleasant day!

    I'm having a really hard time deciding what track to go down to get sailing. Thanks for all the links and advice though. I'm just looking for something minimal that I could know I've built and could have fun sailing this summer. Then in the future I'm sure I will do a much better and bigger boat!
     
  8. Corley
    Joined: Oct 2009
    Posts: 3,781
    Likes: 196, Points: 63, Legacy Rep: 826
    Location: Melbourne, Australia

    Corley epoxy coated

    Well the thing is if you go down the trimaran or proa route you get increased sail carrying capacity which means more sail area and a more efficient higher aspect rig. Normal kayaks dont sail very well because they have very little righting moment which means they have to use inefficient low aspect rigs and very small sail areas.

    The fine hull shapes you require in a kayak for efficient paddling are not particularly suited to a sailing craft unless it gets its righting moment from something else like buoyancy floats at the end of a lever (ie a trimaran) a proa would work ok too and less building and less weight than a tri or cat should paddle ok too with the float attached. It's one of those boat design tradeoffs another option is to look at is a kayak catamaran generally not as efficient as a trimaran or proa though due to weight and you need two kayaks as well.
     
  9. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    There is a down side to sailing a kayak or canoe compared with a regular sailboat. A long and narrow boat wants to run straight and is not very agile in turning. This creates a problem when sailing upwind, as changing tack often takes too long and being so light, the boat is stopped by the wind and is unable to complete the evolution. It’s not a big problem, you do something called boxing, allowing the boat to sail backwards so you end up with a three-point turn, but it can be annoying if you are close to a dock or bank. Most kayak sailors with this problem just use the paddle for a faster turn.

    With Summer so close I would think your best bet to get into the water quickly would be to get hold of a plastic canoe; easier to attach stuff to a canoe than to a kayak. Going back to the plastic pipe idea, you can make an ama with a 10 ft length of 4" pipe for a buoyancy of 55 lb; a 22-15 deg elbow at the bow may help it cut the water; seal the ends with caps. It is best not to use screws to mount it to the crossbeams, maybe pipe support strapping pulled very tight will work.
     
  10. Willzilla
    Joined: Dec 2011
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: New Zealand

    Willzilla Junior Member

    I've learnt a lot so far from all the replies!

    I don't have to get sailing right away but i just don't want to be missing out by the time the winter weather comes round. And if thats the case then oh well! But I don't want to be putting all my money and lots of time into doing a full build of something because I can't be sailing all the time and I don't think its a good investment right now.

    Right now I'm looking at proa's. I'm going to do some sketches and see what people here think. If all goes well I will start a new thread but if it doesnt seem like a great idea then I will look around more. But after looking at them more I like them and it would be functional for what I want. I'm just thinking of a really simple ply proa with a V bottom main hull, and the ama maybe flat or V bottom depending if it will make much of a difference. It would just be frame, ply and wood glue mostly. I can afford the amount of ply and its in the range of amount I was hoping to use.
     
  11. blisspacket
    Joined: Jun 2005
    Posts: 55
    Likes: 1, Points: 8, Legacy Rep: 15
    Location: st augustine

    blisspacket Junior Member

  12. messabout
    Joined: Jan 2006
    Posts: 3,367
    Likes: 510, Points: 113, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Permit me to stick my oar into this conversation. I will argue for practical solutions to your plight.

    1. Any sort of multi will need more material which will translate to more cost and more building grief.

    2. A simply built, small or very small multi will not be much if any faster than a mono of equivalent length.

    3. Multi transport will be problematic. If disassembled for transport, then putting it together and taking it apart diminishes convenience and sailing time.

    4. A small mono of the tender type is far more practical, cheaper and faster to build

    5. Your dad is correct in that the mono will change directions with more certainty. Build a simple mono and go sailing. Two sheets of ply, a chine log, and a few sticks for inwales and easy framing and you have a useable boat.

    6. OK so you are opposed to the PDR. Just pinch the ends together a little bit and it wont be so ugly. It will still take you sailing in relative safety and without breaking the bank. Anyone who casts derisions on your little boat can stand on the beach and enviously watch you sail away.
     
  13. upchurchmr
    Joined: Feb 2011
    Posts: 3,287
    Likes: 259, Points: 83, Legacy Rep: 579
    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Willzilla,

    The kayak trimaran conversions have problems tacking because the hulls have very little rocker. Another problem is that many of the designs have the centerboard (usually leeboard) too far forward. The Little Wing was mentioned before in this thread and it has no real issues for tacking from all reports. It is not an "adaptation" of a typical kayak, but specifically designed.

    See

    Shop clcboats.com » Sailboats » CLC Kayak/Canoe SailRig this is a a boat that is sometimes said to have difficulty in tacking, but with a little technique will do very well. You may not know but first timers on Hobie cats also have tacking issues, a little learning and they can be tacked every time. Just not as easy as a monohull dingy. A canoe adapted to be a tri will also have the same problem.

    One thing I never see from the monohull crowd is specific suggestions. Since I don't want one I can't help.

    Marc
     
  14. Tiny Turnip
    Joined: Mar 2008
    Posts: 865
    Likes: 274, Points: 63, Legacy Rep: 743
    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    This is my new trimaran from

    Solway Dory who know a bit about sailing canoes.

    18foot, just about liftable with 2, fully rigged, more comfortable with more!

    turns very sweetly, (tacks considerably more easily than my Winklebrig, 16ft displacement monohull)

    As I hope the photos show, it has a decent amount of rocker, and of course, the mizzen is a great help in going through the tack.

    [​IMG]

    [​IMG]

    [​IMG]

    Its a bigger boat than you're considering, but do check out the Solway Dory website - lots of ideas there.

    Photos by Greg Spencer, of the Open Canoe Sailing Group.
     
    Last edited: Dec 6, 2011
    1 person likes this.

  15. Doug Lord
    Joined: May 2009
    Posts: 16,679
    Likes: 349, Points: 93, Legacy Rep: 1362
    Location: Cocoa, Florida

    Doug Lord Flight Ready

    TT, that sure is a fine looking little cruising tri-one of the best I've seen!
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.