Want to engineer a small solar powered trimaran. Seeking advice.

Discussion in 'Multihulls' started by JunkRat, Dec 27, 2018.

  1. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member

    Solway Dory Osprey.
    I have a larger older version of this boat and I bless the fact that two of us can carry it fully rigged. It portages well and carries its trolley. Conservatively rigged. Reefing by rolling round the mast. Ive had 11.5 knots. Designed for cruising with a tent.
     
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  2. bjdbowman
    Joined: Apr 2017
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    Location: Florida

    bjdbowman Junior Member

    JunkRat,

    Thanks for the nice comments. I’ll PM you.

    I found the same problems trying to solve our like minded issues with an existing production hull. But I found this boat that has some potential as the main center hull, thought I doubt that you can find one for sale:

    Faering Cruiser | 22'6" Rowing-Sailing Pocket Cruiser https://www.clcboats.com/shop/boats/wooden-sailboat-kits/clc-faering-cruiser.html#line_drawings

    Maybe CLC will build you one… And then you can simply add some hulls from a small production beach cat.

    [​IMG]

    The above was a bit of inspiration for my project as well… My issue is that there just is not anything close to what I want/need. And I also like to build, therefore the EC project. My boat length (18'-24') is only for hull speed… I don’t want to build a huge boat like the 26 that you mentioned above.

    Here is also nice quick little plastic sailboat: Weta - Fun. Fast. Easy. Sailing for you and your family. | Weta https://www.wetamarine.com/ more inspiration for you.

    I want a light easy to handle set of hulls, but plastic is out of the question, glass and wood are heavy, therefore my ideas for the skin on a plastic/composite (carbon) frame with added Kevlar/carbon woven on the outside of hulls.

    I have some concepts but nothing solid at this point… still working on the tender/dingy project as a test bed.

    I also like the concept of the “Herbie Volkscrusier” but a shrunken down version, say in the 24 foot long range with the option to have three hulls and not a proa. Here is a link to Herbie:

    https://proafile.com/multihull-boats/discussion-forum/viewthread/382/

    Just some thoughts… good luck hunting.

    Bowman
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    If you need to portage, the lighter the better. Unless you are a power lifter, you won't be able to carry a trimaran. A 15 foot wooden cedar canoe can be built at about 30 lb. I don't think you got the right information about wood construction being too heavy.
     
  4. bjdbowman
    Joined: Apr 2017
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    Location: Florida

    bjdbowman Junior Member

    gonzo,

    My idea is to move one hull at a time from a small trailer and assemble the small Tri just above the high water line... Lunching will utilize the inflatable rollers as seen on the EC. I think that a SOF should be about 1/6 the weight of a solid plywood S&G hull, but I have not built with this method, so we will see. A cedar strip hull would be nice, but I am thinking utility over looks (function over form), and then there is the cost issue with the cedar here in Florida. I think that JunkRat may have a better SOR than me, as I am budget weary. I believe that JunkRat may be thinking small amas and not a full blown Tri.

    I do like the work from CLC, they have many great boats. Worth looking into.

    Bowman
     
  5. JunkRat
    Joined: Dec 2018
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    Location: USA

    JunkRat Junior Member

    Holy cow, this is an actual production boat. I love it. Really love the way the akas are set up. Ingenious. Mast furling is starting to feel like a killer feature on these types of trips, and I'm thinking now that an oversized sail can be designed for light wind, but sailed partially furled in medium wind and then mostly furled in heavy wind. Rather than having a sail designed for ideal conditions that is dangerous in heavy wind and useless in light wind.

    Anyway, going to research that company and those boats. Great lead. Thanks!

    That is a very nice looking boat, and I agree, 26 feet is a bit big. When I started out I hadn't worked out the various weights, so I'm thinking around 20feet (From a traditional boat) is likely a good size.

    FWIW, I think there are a lot of advances happening in plastic construction these days.... namely 3D printing has exploded, and there are now service companies that will produce whatever you want. EG: You email them a file and they ship you a part. This could be useful for small stuff, but possibly some serious components could be made this way as well. Envelopes and materials are advancing-- there are 3D printed rocket engine nozzles now. Not sure what the service companies can do, but that might help.

    For any given LOA, at an equivalent strength a foam core composite will be lighter than wood. That's just physics.

    I agree lighter is better, but there are tradeoffs. To make it to that 40 mile portage you have to make it thru 1,000 miles of coastal sailing completely unsupported.
     
  6. JunkRat
    Joined: Dec 2018
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    JunkRat Junior Member

    That boat is georgeous but if you want to go that route I would go with just that boat and not add outriggers to it. Plus, it seems that is a luxuruious / expensive way to go. They will sell you a hull kit which is CNC cut plywood for all the parts. That alone is $4,000. Half the cost of a Hobie Island. And that's just doing the easy part of CNC cutting plywood.

    All in it looks like building that would probably be $40,000. Much of that is your time, but you time has value too.

    If you have a lot of time and no hobbies, and plenty of space, like a backyard and a wife that will put up with it taking a long time then building a boat is a fine hobby. You can take a break for weeks or months when it becomes too much. It doesn't cost you much to take up your back yard, you can take time to find parts on sale or iterate on your ideas until they work in practice the way they did in your head.

    I'm speaking from experience here and am in the middle of a large build myself. I've had to focus and it has taken more time and money than intended, but it is letting me get the exact thing I need and it is in my area of expertise and so I'm having a blast. Boats aren't my area of expertise and I don't have the driving need to get exactly what I want there.

    All that said, if you want something like the above, you might have the best results doing a full size model in foam. Something like XPS or urethane. Get that the way you want and then you can use it as a male mold and make a female mold from it. Then you could vacuum bag infuse the whole hull. I think that this method of construction would reduce the effort to 2-3 major pieces. They would be large infusion projects each, but a lot easier than actually building it. So you do your physical shaping of the shape using something forgiving and maleable, and then you make a molde from that, and then use that mold to make final high precision parts.

    This may be what you were already planning, but I expect it wold be a lot easier than assembling a couple hundred CNC cut pieces of plywood and hand glassing them.

    Just my thoughts having built some things made my own composits (But never built a hull and never done this modern infusion type of composite.)
     
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  7. John Persson
    Joined: Dec 2018
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    Location: Canada

    John Persson New Member

    My sailing kayak is now 95% completed and what a learning experience it has been!

    It is basically a floating sailing frame made from aluminum pipe with a kayak attached. I bought 20' lengths of 3/4", 1" and 1-1/4" schedule 40 aluminum pipes and cut, drilled and bolted as necessary.

    The amas were made by carving dock flotation foam into a hydrodynamic shape, attaching plywood top and bottom with through-bolts and sleeves and covering with layers of roofing tar, 10 oz fiberglass cloth and marine epoxy.

    It has 140 sq ft of sail area in a conventional Bermuda rig of mainsail and jib; which in itself requires a large amount of deck area as each sail sweeps a 10' radius. A bowsprit was required to accommodate the forward projection of the foresail.

    The kayak required reinforcement on the keel, bow, stern and where the mast steps into the hull. The mast has six stays: one forward to the bowsprit, one to the extreme stern, and two to each side attached to the main forward amas.

    I sewed in two reefing points on the main sail and will carry a storm jib for strong winds.

    Due to the remote area I want to traverse, power generation was a necessity for essential equipment such as GPS, emergency beacon, marine radio, nav lights, bilge pump, etc.

    I installed 2ea 100watt solar cells, a vertical turbine wind generator and a bicycle with an alternator attached via a fan belt to an alternator, charge controller and a small automotive AGM battery.

    The large sail area requires a large rudder (when compared to a typical kayak rudder) and for redundancy I put bearings on the rear amas to make them steerable as well.

    At times I will need to sail 24/7 so a self-steering system was installed utilizing a wind vane linked by mechanical servos to a trim tab on the main rudder all fabricated using materials I had on hand. The tools used were simple; circular saw and saz-all for the foam, angle grinder for cutting the aluminum pipe, portable drill and spanners.

    The big safety issue with a trimaran is the possibility of a pitch-pole, so I installed two horizontal foils up front with trim tabs operated by linear actuators.

    The loaded weight with three months of food, 20# of propane for cooking and 20 gallons of drinking water will be about 1000#. LaTida.png I'm working up a 3D model to document the build and although it is still a work in progress I've attached a view from underneath showing the structure and flotation.
     
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  8. rob denney
    Joined: Feb 2005
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    rob denney Senior Member

    Sorry, I was meaning you could get them built. It will cost more than buying second hand, but you should end up with what you want rather than the compromises inherent in buying any of the comparatively heavy, slow boats mentioned.
     
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  9. Niclas Vestman
    Joined: Aug 2017
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    Location: Malmoe, Sweden

    Niclas Vestman Junior Member

    I did research the small multi topic and found an abundance. Mostly custom though. For factory build, have a look at the french Astus trimaran. Range of 16.5' to 24'. Other interesting ones. Mike Waters w22, Husky 6.2, Sardine Run 19, Custom project Osprey built on Nacra amas. Also check out YAT yet another trinado, trinado, and TC 627, among others. Them there are the resources, www.smalltrimarans.com (i think) or small trimaran designs. Can't quite seem to remember. Also don't forget Kurt Hughes designs and the Scarab trimarans.
     
  10. Niclas Vestman
    Joined: Aug 2017
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    Location: Malmoe, Sweden

    Niclas Vestman Junior Member

    Smalltrimarans.com and smalltridesign.com
     
  11. Niclas Vestman
    Joined: Aug 2017
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    Location: Malmoe, Sweden

    Niclas Vestman Junior Member

    http://multihulls.org/?page_id=200&id=335

    Don't know if this is still for sale. Built by a swede and had a thread here on boatdesign.net. probably as light fast and as much sail you can get in that size bracket. The multi 23 and Diam 24 are 2 other factory built racing or semi racing tris coincidentaly both designed by VPLP.
     

  12. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Cedar (or any other species of wood) strip construction does not need to be finished like a fancy piano. A painted finish can be made quite fast and economically. SOF can be quite light, but then it will be fragile.
     
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