Build time 40ft catamaran

Discussion in 'Multihulls' started by bluebox3000, Jan 8, 2014.

  1. Richard Woods
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    Richard Woods Woods Designs

    I lived on a Hinemoa in Wales for 3 months when I first worked for James Wharram

    Richard Woods
     
  2. gonzo
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    gonzo Senior Member

    Bluebox: you can definitely build a quick and dirty boat in you time frame. There is no need of fairing or fancy finish to make a structurally sound boat. The finish usually takes the larger percentage of the total time. Plywood construction with a Vee bottom goes together very fast. Another fast method is one that the Gougeon brothers used. You join several sheets of plywood with fiberglass tape to the required size. Cut both sides of the hull and fiberglass the keel and stems together. Spread the sides and brace them to the shape you want. Lay fiberglass on both sides and put in bulkheads.
     
  3. cavalier mk2
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    cavalier mk2 Senior Member

    Character forming.....So are any of your flat panel designs suitable for the foam laminate table and assemble method? I'd think the boats like Romany or your V hull design would translate well. Is it worth your time to offer that option?
     
  4. Richard Woods
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    Richard Woods Woods Designs

    Yes, my Surfsong, Gypsy, Windsong, Romany, Flica, Mira, Mirage, Meander, Rhea designs (I think that's all of them) are all flat panel foam sandwich hull boats. Plans are available and home builders have built boats to each design.

    The Windsong and Gypsy that I built for my own use both had flat panel foam hulls.

    Richard Woods
     
  5. bluebox3000
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    bluebox3000 Junior Member

    Looks like plywood/flat panels are the method to focus on. Less fairing and time consuming curves. Any advantages going with foam and infusion vs. plywood for the flat panels?
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    Can't really see anyone needing anything bigger than Romany or Mirage....
     
  7. cavalier mk2
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    cavalier mk2 Senior Member

    Both have their merits, I haven't played with infusion so the only observation I can offer is you probably already have the tools and skills for plywood. cost them both out and factor in some waste for getting the infusion process down.
     
  8. Richard Woods
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    Richard Woods Woods Designs

    Agreed. I wouldn't want to own a boat over 35ft for cruising with a couple (and haven't done so)

    We owned a Romany for 3 years (it was built in ply/epoxy by a chiropractor who hadn't built a boat before) and cruised it twice to the Bahamas, sold it to a family who did the same thing. And, being lake sailors, they had never sailed on the sea before.

    A flat panel foam sandwich Mirage was built on a beach in Panama and then sailed singlehanded back to the UK

    To the OP you have to include your familiarity with the materials as well as longevity, resale, insurance when you consider which material to build in. Building the cheapest hull often isn't the best deal in the long run

    Having said that, from a structural/weight point of view there won't really be much in it. At least not by the time you've got the boat in the water and are off cruising.

    And another factor, people don't usually like a bare fibreglass interior, they prefer a wood one. So if you build a foam boat you may well add weight making it look "pretty", weight you don't need to add if building in wood from the start. Racers of course don't care about the interior

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  9. John Perry
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    John Perry Senior Member

    Re this question as to whether plywood or foam core is the quickest way to build a one off hull; I would like to believe that foam core with flat panels laminated on a table is quicker, but I find it hard to be convinced, despite the claims made by certain boat builders who are more experienced than myself.

    Consider plywood first. These days we can get every piece of ply pre-cut to millimeter accuracy by computer controlled machinery. Some of the panel edges then need to have scarfs cut, quite a rapid process if a number of panels are stacked then the edges power planed. Next we loosely assemble the structure with wire ties, temporary screws and some temporary framing (for example to align bulkheads from the workshop floor.) When I have built boats (admitedly small ones) I have managed to glue the scarfs 'in situ', this avoids the need to lift and position any piece of ply more than about 2.4m long. Then we permanently join the panels with a combination of internal glass tape, structural epoxy fillets and wood 'cleats'. After that we seal all the wood with three coats of epoxy, embedding glass cloth into one of the coats on the external surfaces only and using peel ply to leave most of the external surface ready for the first coat of high build primer.

    Now foam core, using a laminating table. First we build the smooth topped vacuum proof table, no small job in itself. Also note that the table will take up a lot of precious workshop space. As with ply, we can use cnc cutting for all the core panels but since we probably later need to do some further work on the edges of many of these panels we may not be able to transfer the accuracy of the cutting process to the finished product as well as we can with plywood. Next we accurately assemble the core panels and glass on the table and for at least some of the panels we set up 'formwork' along the panel edges to allow flanges to be moulded to the panels so that they can be glued together. All this is work not applicable to plywood construction. Also at this stage we need to fit inserts of high density foam wherever loaded fittings will later be attached - more work and more foresight needed than just fitting backing pads behind fittings on a ply structure. Then we do the resin impregnation with either hand laminating plus vacuum bagging, or infusion. I suppose this stage coresponds to the resin coating and glass cloth sheathing necessary with plywood, maybe with comparable manhours required. Next the assembly and joining of the panels to make a hull structure, again with some temporary framework to support bulkheads etc. This is a not dissimilar process to the assemly of a plywood hull but it seems that with foam core you do need to manipulate some panels that are the full length of a hull, not so easy if you are working alone. You now have a smooth external surface transferred from the table onto much of the external hull surface, but you need to do bogging and fairing around all the joints between panels. The need for this can be reduced by moulding recesses into the edges of the panels so that tapes don't sit proud, but that's more work earlier on. Now you are ready for final coats of primer and topcoats, similar work as for painting a plywood hull.

    Other things being equal, foam core is lighter than plywood and it does seem that foam core boats have a higher resale value, more than compensating for the somewhat higher material cost. However, based on the above, foam core looks to me like significantly more work. Basically, with foam core you manufacture your own sheet material before you can start building the boat, with plywood you buy your sheet material ready made. Do tell me where I have gone wrong in my thinking!
     
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  10. Richard Woods
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    Richard Woods Woods Designs

    One additional factor is that you waste a lot of plywood.

    After building our Skoota 28, which used about 100 sheets of ply, we have probably 10 sheets left in mostly useable scraps - but we don't need them unless we build yet another boat. The small offcuts we burnt as we went along (we have a woodstove at home).

    Compare that to the foam sandwich Eclipse which I built. No foam wasted (OK maybe1sqm), very little glass, maybe 10kg, and resin - which you always waste whether its a wood boat or a foam one.

    Otherwise, I agree with your last comment

    Richard Woods
     
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  11. groper
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    groper Senior Member

    To setup a full length panel - 40ft x 6ft - and infuse it on a table, i can do by myself between breakfast and lunch time, from raw materials to waiting for cure. This is for one experienced person working, not a beginner. Compare this to how long it takes to do all your multiple coating of the plywood and sheathing it in glass, nevermind how many lumps and bumps youll introduce along the way. My personal opinion thinks there is little difference between either method in terms of time - once youve actually done it both ways.

    The thing your missing, is your not considering premade sandwich panels bought from a professional manufacturer. Any developed country has companies which can supply pre made panels with what ever core and laminate you desire... If i were to build again, i would use a combination of premade panels and some of my own infused panels to save a bit more time where appropriate. In australia, we have companies which will make full length panels, complete with gelcoat or whatever other details you specify, packed into a 40ft container and shipped to your door for a reasonable price. If the yacht designs were done to take advantage of these services with less emphasis on aesthetics, a very speedy build could result.

    But to reiterate what RW said very briefly, its not the building of the hulls which takes the majority of the total build time. They are only a very small part of the total project hours - despite being the largest physical parts of it... And so in the same vein, the difference between foam flat panels or plywood, is also very small compared to the total hours in the entire project. Most projects ive seen take a similar amount of hours regardless of composite panels or plywood structure.
     
  12. cavalier mk2
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    cavalier mk2 Senior Member

    Geez you guys, I cut to a line, spile, loft and when I'm done with a panel the scraps I can hold in one hand. The late Phil Bolger was a master at panel layout and included the cut layout in his plans. I actually make scale patterns of components and move them around on the scale 8'x4' grid to maximize material. It takes a little extra time but at sheet prices it's worth it.

    CNC cutting is neat but you don't really need it, developing skills saves money. Pre made panels are an intriguing concept for sure. Might be worth it to more than a few instead of mastering the vacuum pump.
     
  13. groper
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    groper Senior Member

    Or master many things.... use a combination of precut CNC routed panels, build your own panels etc... boat building is about finding many novel ways of doing many different things...
     
  14. cavalier mk2
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    cavalier mk2 Senior Member

    Yes it is, I was just thinking that for the person who was jst going to build 1 boat learning some of these things didn't make sense. I used to program CNCs as a machinist I should get on the boat CNC bandwagon but don't want to spend on the hardware.
     

  15. david@boatsmith
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    david@boatsmith Senior Member

    Richard has it wrong... I'm only 6'2". And ther is only 4 1/2' of headroom in a Tiki 30. Wharram calls the Tiki 30 his largest backpacking boat.
    Other than those minor points he is spot on.
    It is difficult to get decent headroom in a boat of this form in a short loa.
    Richard's chined or tulip flared hulls provide much more interior volume in a form that is far more suitable for interior accommodations. The Eclipse offers remarkable accommodations for a 32' boat. When I was aboard Richards Transit I was very impressed with the sheer interior volume. Achieving 6'6" headroom thruought will indeed limit your options and increase the cost.
     
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