Layup for 15ft Canadian canoe

Discussion in 'Fiberglass and Composite Boat Building' started by hardguy007, Aug 13, 2012.

  1. hardguy007
    Joined: Jul 2012
    Posts: 36
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Ballymoney

    hardguy007 Junior Member

    As the title says what's a good layup schedule for a 15ft canadian canoe. Also what's the best wood to use on it?
     
  2. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Are you are building a completely fibreglass canoe ?

    is the wood just on the decks, or are you really talking about fg over timber construction ?

    When you say 'wood', are you talking strip planking or plywood ?
     
  3. hardguy007
    Joined: Jul 2012
    Posts: 36
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Ballymoney

    hardguy007 Junior Member

    Yes, just standard fiberglass construction. By wood i mean the wood for the gunnels, seats etc.
     
  4. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    A totally fiberglass canoe is going to be a lot heavier than one with some sort of core.

    The core can be wood or foam.

    Foam would be the easiest to build with, but more expensive.

    I have no idea where 'Ballymoney' is , so I don't know what sort of timber you have available

    Are you committed to completely fiberglass ?
     
  5. hardguy007
    Joined: Jul 2012
    Posts: 36
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Ballymoney

    hardguy007 Junior Member

    Its in Northern Ireland. Yes is will be completley fiberglass which is common place over here. Average weight seems to be around 25-30kg leaving around 18-23kg for actual gelcoat/glass/resin.
     
  6. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    I made 17' canoes a long time ago http://forum.woodenboat.com/showthread.php?69360-1942-peterborough-12-trapper Post #3 is a copy of the offsets that I used to make the plug and mold. It's difficult to keep the weight down, the gelcoat alone was pushing 9 lbs. I used polyester, so some 3/4 oz mat was involved which is not weight efficient.

    It might be better to paint them after demolding, but to lay up without gelcoat is hard to do without getting a lot of pinholes in the outside surface.

    Whether you use epoxy or poly resin makes a big difference. You can use layers of 10 oz cloth without mat in between with both resins, but only wet on wet with poly and there is a bigger chance they will separate if flexed too much, compared to epoxy. With lightweight layups there is more print through also.

    I always used gelcoat and a first layer of 3/4 oz mat to minimize print through and to bind the gelcoat to the first laminations of cloth.

    The lay ups are done according to the shape of the hull or the abuse the areas might receive. The bottoms are big, flattish areas and have a tendency to deform and oil-can. While the bows and sterns get all kinds of strength from their shape and the built in flotation air chambers, they're the places that get solid dead on hits, as compared to sliding over rocks abuse that the bottom gets.

    My theory is to built as light as possible and try the boat out, and then add to the weak areas.

    If you're using poly, (BTW, there are two kinds of polyester resin, isothallic and orthothallic. Iso is better and that's what I used) this is what I'd try. (BTW, all this is using non-waxed gelcoat and resin) Work in a reasonably controlled environment, temperature, humidity, ventilation etc. Not in the rain, not in the sun, not in damp/cold conditions. I'd do the gelcoat and let that cure for 3 to 12 hours (use a fan to blow the styrene out of the mold).

    Then a fairly resin rich 3/4 oz mat with enough hardener but not too much. A hot mix will shrink and pull the gelcoat away from the mold. Once that has got past the heat of exotherm and is set but still 'soft' (the 'green' stage, which btw is a good time to trim excess with a razor knife) carefully scrape off, with a sharp paint scraper, any lumps or fiber splinters that will hold the next laminations off the surface. Vacuum/ clean out the residue. Then 2 layers of 10 oz cloth overall should be put on, both at the same time. You can put the mat and both layers of cloth on all at one time, and it is the faster, better way, but you have to watch out for exotherm heat build up. Do a test to see if all 3 layers can be put in dry and still be wet out from the top.

    Use a paint roller to put on the resin (and a brush too). Since the canoe is mostly dish shaped surfaces, straight hard ridged bubble buster rollers don't work too well unless they are barrel shaped. Once the cloth is down and wet out, a flexible plastic squeegee (or your hand) works really well for consolidating the layup and especially for piling up the excess resin so you can remove it. You have to watch out for pulling the fabric away from the mold with the squeegee (and the roller too), so it works best to go from the gunnels to the keel.

    One or two more layers are needed in the bow and stern. Depending on how fine an entry you have on your B & S, those areas are very hard to get at with rollers and squeegees, so I formed a 1/4" smooth rod into a shallow 6" long arc with a handle that would push the laminate into the slot and also slide along the laminate to "squeegee" out bubbles. It's also very hard to get gelcoat in there, you have to slop it in somehow without scraping off the PVA and wax. Good luck on that.

    The sides will be flexible with this layup but thats ok. The bottom needs more though or it will oilcan. The areas that will oilcan are the flattish areas. Once the bottom starts transitioning into the sides the curve in the "chine" adds strength, so the extra reinforcement doesn't need to go into that curve, but just approach it. Some companies put a layer of 3/16" thick foam there with a layer of glass over it to create a sandwich. I would put foam ribs every foot or so and individually cover them with a layer of 3/4 oz glass and a slightly bigger piece of cloth.

    Any other things like seat supports or supports for foot "rests" (They help a lot to give you something to push against when paddling hard) should be laminated in now too. I put an air chamber in each end for flotation by hot glueing two thin pieces of foam in place and laminating over them. Solid foam would have added another 4-6 lbs of weight.

    If you don't know if the layup will work, at this stage leave the inside unfinished and finish the boat. That way you can test it and have a good surface to add more laminates to, if you have to. Otherwise, I would use a sharp paint scraper to get the big lumps and sharp edges tamed down a little. I would wipe it down with acetone to wake up the surface and make it seem a little more receptive, and then give it a thin coat of latex porch and floor enamel. That would make the unwaxed, unsandable surface easily sandable. After a little more scraping and a fairly thorough sanding with 80 grit, one more coat of enamel was applied which left the surface very smooth with no chance of any injuries by fiberglass snags and needles.

    I used Douglas fir for the gunnels and ash for the thwarts and sliding seats. 3/16" woven nylon rope for the seat bottoms and stainless for the fastenings.
     
    2 people like this.
  7. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Does that mean you get a 50 kilo boat in the end ?
     
  8. hardguy007
    Joined: Jul 2012
    Posts: 36
    Likes: 2, Points: 8, Legacy Rep: 10
    Location: Ballymoney

    hardguy007 Junior Member

    No 25-30kg finished
     
  9. midnitmike
    Joined: Apr 2012
    Posts: 257
    Likes: 20, Points: 18, Legacy Rep: 167
    Location: Haines and Juneau

    midnitmike Senior Member

    That was a great post SamSam.

    MM
     
  10. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Thanks. I usually never get any feedback and begin to wonder if I'm just senselessly blathering or what.
     
  11. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    Yes, some really usefull hints here.

    This problem with getting access to the bow and stern tried my patience a lot too.

    I did a canadian canoe, where the bow and stern are supposed to be identical, and trying to glass inside them was a firggen nuisance. Coupled with that, was the desire to put a compartment at each end. Fitting the bulkheads and hatches was a very tedious business too.

    If I am ever inspired to do another one, I swear I will make blunt ends for the canoe, and mould the bow and stern as separate pieces. The moulded bow and stern sections will be attached and glassed over when the main hull is covered.

    eg.

    http://greencanoe.weebly.com/turning-over-a-new-canoe.html
     
  12. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    Yes, that looks to be a challenge on that canoe. In the ends, I would slit the cloth on the centerline back to the point where the cloth would start to get difficult trying to make it conform to the narrowing ends. I would do one side at a time, each side cut a few inches long so when it was done, the glass in the stems was lapped and was 2 layers thick for each 1 layer of glass in the main hull.
     
  13. rwatson
    Joined: Aug 2007
    Posts: 6,163
    Likes: 495, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    No - you missed the point. Its getting inside the sharp ends, the outside is a doddle.
     
  14. midnitmike
    Joined: Apr 2012
    Posts: 257
    Likes: 20, Points: 18, Legacy Rep: 167
    Location: Haines and Juneau

    midnitmike Senior Member

    No, it was a very concise description of what appears to be a common layup technic for canoes and kayaks. It also perfectly explains the 4" blister I found in one of the kayaks I'm working on. When I cut out the blister I observed a cloth on cloth laminate that had separated with no appearent damage to the outer skin. I think this would tend to support the use of epoxy over polyester resin when using this layup schedule.

    MM
     

  15. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    No, I didn't. I'm describing working inside the sharp ends. I made pure fiberglass canoes in a female mold so there was no outside glassing or wood strips involved.
     
Loading...
Similar Threads
  1. boatymcboatface
    Replies:
    1
    Views:
    2,241
  2. Jason Rodgers
    Replies:
    8
    Views:
    1,082
  3. Midday Gun
    Replies:
    8
    Views:
    2,106
  4. cadmus
    Replies:
    13
    Views:
    2,686
  5. PickNasty
    Replies:
    17
    Views:
    3,744
  6. JSthebuilder
    Replies:
    2
    Views:
    1,314
  7. Jeff in Boston
    Replies:
    14
    Views:
    1,804
  8. Gasdok
    Replies:
    10
    Views:
    2,595
  9. fallguy
    Replies:
    19
    Views:
    2,571
  10. DogCavalry
    Replies:
    9
    Views:
    1,529
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.