Info need for sailcloth.

Discussion in 'Boat Design' started by aliaj00, Apr 3, 2012.

  1. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    This is a canoe, interested in a sail assist from time to time (my assumption). Anything more then 3 or 4 ounces is just over kill, weighty and likely not to produce a portable, stowable rig, that sets well in the wind strengths they'll use the boat in.
     
  2. MastMonkey
    Joined: Oct 2009
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    MastMonkey Junior Member

    The Wa'Apa is a 24 foot outrigger sailing "canoe", very different from a sail assisted light boat. It is a Polynesian design configured as either a proa, a single outrigger with a tacking rig, or a trimaran. Either way it is primarily a sailboat, with more in common to a low cost trimaran than a simple canoe. There is a tremendous variability in the rigs. Several use second hand mast and sails, some use wind surfer rigs, other go the traditional route and make a crab claw or simple sprit. My own recommendation would be that if the hull is well built out of good materials it is worth the extra cost to put a good sail on it. I would use 4-5 ounce Dacron personally or consider something lighter but batten it. A crab claw sail made out of Tyvek or polytarp would be cool, but again it depend on the conditions they want to sail in.
     
  3. aliaj00
    Joined: Sep 2009
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    aliaj00 Junior Member

    HI all,

    i didn't expect so much support for my question. :) thanks a lot i learned almost everything from this forum.

    and yes this is going to be a cheap "economical for me" sailing trimaran as we are not allowed to have motors and the patent for the motor if and if i get permission is 600$+ so my budget is off limit as this is going well beyond my money expectation. so i save each month a little to be able to finish it.

    Currently i have made the sail from a polyester cloth around 300gram per meter and unfortunately the mast i used was an aluminum one, but not the 6061 and it got bend while trying to make some dry tests on it. actually it was designed for the circular step stairs "as middle support" but i thought it would have been good enough. it was`t. :( .

    i have not put it on sea as the mast needs to be replaced. also the paint has not been put down as i have not find a good replacement for it. no boat supplies around and building from very various thing that can do the job. many seems to do it but i am afraid of screwing it and still not decided.

    Also i looked at some SOF kayaks and they have used nylon to give scratch resistance. can i add a layer of common nylon cloth to the fiberglass_epoxy on the outside?????? as most of the shore here is rocky???????

    to the last comment from MastMonkey the hull is exterior grade 6mm plywood reinforced with plywood_epoxy at the stations and everywhere i seem it would be needed "joints"so comments are very very welcomed. i will attache some photos later to show the joints.

    BR aliaj00
     
  4. hoytedow
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    hoytedow Carbon Based Life Form

    You may want to build a hollow wooden mast. They are not difficult to build using 6mm plywood and spruce or other coniferous wood and are much stronger/more rigid than your typical thin aluminum tubing.
     

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  5. aliaj00
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    aliaj00 Junior Member

    Hi hoytedow,

    thanks for the help. What might be the dimensions for a 6 Meter Mast and 4.5 Meter boom. that will be much cheaper.

    BR Aliaj00
     
  6. hoytedow
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    hoytedow Carbon Based Life Form

    I added what I think would be good minimum dimensions at the base, then tapering back from 15 cm at the base to 10 cm fore/aft at the top. Width would stay the same down the length of the mast. Not being an expert I welcome any corrections and revisions from the more knowledgeable members.
     
  7. aliaj00
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    aliaj00 Junior Member

    Guys i have found this page: http://www.themultihull.net/st2.htm

    its says one can build a fiberglass mast with polyester resin. does it sound realistic for my project. for 6M mast and 4.5M boom????

    thanks,

    Br

    Aliaj00
     
  8. hoytedow
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    hoytedow Carbon Based Life Form

    He said if he were to do it over he would be using epoxy. So would I. You should start with the wood mast since your boat is plywood. You can put one layer of fiberglass cloth over it to make it very strong.

    = cheap/economical
     
  9. Petros
    Joined: Oct 2007
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    Petros Senior Member

    I would not use nylon fabric over a fiber glass hull. If you are worried about durablity just put another layer of fiberglass over the areas you want to protect. Nylon expands, or relaxes, when in comes in contact with moisture (it absorbs H20 into the matrix and gets longer), so it is not a good choice for protecting a hull. Polyester would be much better, it does not stretch nearly as much, nor does moisture affect it. It would have to be glued down over the surface since you do not want moisture to be trapped between the hull and the fabric. Which is just as well why you just add another layer of fiberglass.

    The skin on frame allows the fabric to dry out since you do not have it up against a surface that can trap moisture.

    I have also built a number of wood masts, much less costly than just about anything else you might use.
     
  10. aliaj00
    Joined: Sep 2009
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    aliaj00 Junior Member

    Hi guys,

    thanks for the help. hoytedow if i put the fiberglass on it can i use many butt joins for the mast. i was thinking a little more after your post and i have some strips of 16x16mm that are about 5M. can i use a pvc tube and use it as a guide to put the fiberglass and than put strips of wood around it and again fiberglass???? so it forms a sandwich and as they are rectanglular to use thickend epoxy with sawdust to fill in the gaps. if Ok, what diameter can i use to build it like this.

    Petros, thanks for the help now i understand it better so nylon is out of the question. Can i use some strips of wood on the underneath of the boat over the fiberglass to protect the fiberglass from the shore????
     
  11. aliaj00
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    aliaj00 Junior Member

    photos attached

    photos of station 2 attached
     

    Attached Files:

  12. aliaj00
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    aliaj00 Junior Member

    Wa`apa data as per the book
    overall 23’8”(7200mm)
    Hull width 211⁄4”(540mm)
    Overall width 11’(3370mm)
    Draft 6”(150mm) @ 675 lb (306 kg) displacement
    Hull weight 174 lb (79 kg), 58 lb (26 kg)per section
    Weight fully rigged 275 lb (125 kg)
    Sailing rig type Tacking or Shunting
    Sail area 84 sq ft (7.8 sq m)
    Tacking, 126 sq ft
    (11.7 sq m)
    Shunting
    Construction method Plywood
     
  13. hoytedow
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    hoytedow Carbon Based Life Form

    As I said, I am not an expert. I would avoid many butt joints using no more than 2 per side and staggering their placement so they are not near each other. Get an expert's opinion. Mine doesn't have much weight in this regard.
     
  14. aliaj00
    Joined: Sep 2009
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    Location: albania

    aliaj00 Junior Member

    Hi Hoytedow,

    I was talking to a friend of mine after work and he has another aluminum tube like mine "construction type but unknown mark" that is 60MM diameter and i think 2.5 or 3 mm thick. i seated a 75Kg friend over it at 5.2M distance and it bends but not break. and after he gets up it regain its shape.

    Guys what do you think of this tube. can i use it without pushing the sail too hard.

    please help on this as it is 100$ piece of 6M and for me its not cheap :) :p :D

    Thanks all,


    BR, Aliaj00
     

  15. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If you're going to use aluminum, you have to be careful about the alloy. 6061 is what you want, nothing else will do. Some will try to sell you 6063, but it's half as strong! None of the 5000 series would be recommend either. Simply put, to make a judgement about a suitable spar material, we need the full set of spec's. What is the alloy, the length, the diameter, the wall thickness, extruded or welded, is it tubing or pipe (big difference), etc.

    In regard to you mast's scantlings, a wooden box mast wouldn't be hard to make, but would be exceptionally heavy with plywood and not as strong as a solid wood box mast. Birdsmouth would be an option, though more difficult than a box. As to sizes for you mast, the 3"x6" (80x150 mm) mast shown above would only be suitable on a stayed rig. It's rectangular shape isn't well suited for a free standing rig. It's also massive, but I'm not sure about the rest of the details concerning this rig, so it may need to be this size. Without appropriate specs on the boat and proposed rig, any spar dimensions are purely speculation.

    Fiberglass masts are heavy and very flexible, so with some rigs this may be desired, but in most cases not so much. The reason you don't see any masts made from 'glass, even with epoxy, is it's a lousy material for a mast. It's too heavy, too flexible and too costly if you use sufficient "fancy" reinforcement, to make it a stiff enough section, to be applicable.

    In small craft, wood and aluminum are the hands down favorites. Wood is better in smaller sizes than aluminum, both in cost and weight, but once your stick gets over say about 25', then aluminum becomes more desirable in physical attributes.

    You can improve abrasion resistance by sheathing the hull with a polyester fabric (Xynole) or a modified acrylic (Dynel). Both will greatly improve abrasion resistance, but offer no strength. They are highly flexible too.
     
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