I have a 1931 Old Town OTCA 17 that I got from a friend about 15 years ago. He simply asked that I take it away along with the utility trailer I was buying from him. I re-canvassed it once but need to do it again. As an architect/designer I like to explore alternate methods of construction on almost everything. The stems were re-cut using marine grade plywood and have held up quite well. I’m thinking now of using a poly coated nylon duck rather than canvas so I can save a lot of weight. I know this will stand as heresy to many members, but I just need to ask. The material seems to have enough stretch to pull tight around the hull. In cut or tear tests, it held up to the same abuse as a piece of canvas when hit with a knife. The resulting clean cut can be patched with a variety of patch kits made for dry bags, jackets, inflatable boatsm etc. What am I not thinking of in this scenario, oither than losing the 'traditional' aspect? I'm looking to make a serviceable craft, ready for most lakes, swamps or mild river runs.
Alternate coverings?
- Thread starter JABO
- Start date
Todd Bradshaw
Sailmaker
The polyurethane coatings used on nylon tend to be somewhat fragile. Everybody has probably see some old nylon bag or garment where the coating is starting to peel like a bad sunburn, or starting to smell REALLY bad (we used to call it "bear-barf syndrome" and it eventually happens to a lot of nylon tents as they age). Most average coatings also don't tolerate constant exposure to water or dampness for extended periods all that well. There are exceptions, like those premium grades used for some inflatables and higher-quality dry bags, but most common coated duck fabrics may delaminate from overexposure to wet conditions and may not even be completely waterproof to start with. The premium coated nylons are usually sold as being "heat sealable" and have a heavy coating that you can actually bond to itself with an iron (similar to what's used on Therma-Rest mattresses, Cascade bags, etc.). It's great stuff to make your own gear from, but somewhat hard to find and pretty expensive when you do find it.
Most nylon has a pretty poor UV life, so indoor storage would be a good idea and most nylon duck isn't terribly abrasion resistant. The other problem with nylon is that it will most likely continue to stretch. It may fit snugly today, but it very well may be starting to get baggy next week. After a few days in the water, it may get really baggy. When the boat dries out, it may shrink back up, but only while it's kept dry.
For a similar weight material with a proven track record, you might want to search the forum archives for threads about Dacron covering. It is thin and light, like nylon, but has rather different characteristics that make it more suitable for canoe covering. Like any material (including canvas) it has it's good points and not so good points, but I think you'll find that it beats coated nylon on nearly all points by a huge margin.
Most nylon has a pretty poor UV life, so indoor storage would be a good idea and most nylon duck isn't terribly abrasion resistant. The other problem with nylon is that it will most likely continue to stretch. It may fit snugly today, but it very well may be starting to get baggy next week. After a few days in the water, it may get really baggy. When the boat dries out, it may shrink back up, but only while it's kept dry.
For a similar weight material with a proven track record, you might want to search the forum archives for threads about Dacron covering. It is thin and light, like nylon, but has rather different characteristics that make it more suitable for canoe covering. Like any material (including canvas) it has it's good points and not so good points, but I think you'll find that it beats coated nylon on nearly all points by a huge margin.
Todd_
Thanks for the input. I've just come in from putting the first coat of varnish on the inside of the hull. I can't wait to get it back on the water!
I'd forgotten the aspects of peeling, though doesn't that mostly occur with continued flexing and bending? And the 'bear-barf', well yeah that could be a problem if the fabric gets no chance to breathe. As for cost, what I have found seems to be close to the same range as canvas per yard, and would appear to be more of a one-step application than the filling, sanding and painting required of canvas.
I found a wide variety of fabrics at settlefabrics.com and am mostly considering the following:
200 Denier Heavy Coated F/R Oxford - New!!!
4 oz per sq. yard 200 Denier. This is not your typical, lightly coated nylon oxford; in addition to being flame retardant, it has a super heavy 1-1/2 ounce flame retardant urethane coating! Giving its superior characteristics, this fabric is waterproof and perfect for applications where weight is critical with out moving up to a heavier fabric. Perfect for displays where flame resistance is required!
Uses: Display booths, tarps, ground tarps, tent floors, stuff sacks, light weight bags and much more!
Width: 60"
Colors: Red, Orange, Yellow, Green, Royal, Purple, Maroon, Magenta, White, Silver and Black.
$7.95/yd
I realize I might be pushing for too much weight savings, but I like to experiment and push the limits as far as I can, Given that price point, I figure I can cover the boat for about $55. If I use some neoprene repair tape (double sided) to hold it along the keel and gunwales (about $15) and cover the stems with skid plate material (another 20-30) I've got the boat covered for under $100 with a relatively low labor factor. At worst, if it does fail miserably I can pull it apart and rework the fabric to make a cover for storing the boat. Then I can go back to the 'old reliable' canvas and filler method and paddle away for another 20+ years.
The boat was initially set up with a sailing rig, and the bow seat has the hole for the mast to fit through. I've seen your sail drawings years ago and may get back in touch about setting it up to sail again. I've got a few left over rudders and dagger boards from old Sunfish that may work as parts for this, but not sure how to fashion a mast and gaff rig.
Thanks,
Allen
Thanks for the input. I've just come in from putting the first coat of varnish on the inside of the hull. I can't wait to get it back on the water!
I'd forgotten the aspects of peeling, though doesn't that mostly occur with continued flexing and bending? And the 'bear-barf', well yeah that could be a problem if the fabric gets no chance to breathe. As for cost, what I have found seems to be close to the same range as canvas per yard, and would appear to be more of a one-step application than the filling, sanding and painting required of canvas.
I found a wide variety of fabrics at settlefabrics.com and am mostly considering the following:
200 Denier Heavy Coated F/R Oxford - New!!!
4 oz per sq. yard 200 Denier. This is not your typical, lightly coated nylon oxford; in addition to being flame retardant, it has a super heavy 1-1/2 ounce flame retardant urethane coating! Giving its superior characteristics, this fabric is waterproof and perfect for applications where weight is critical with out moving up to a heavier fabric. Perfect for displays where flame resistance is required!
Uses: Display booths, tarps, ground tarps, tent floors, stuff sacks, light weight bags and much more!
Width: 60"
Colors: Red, Orange, Yellow, Green, Royal, Purple, Maroon, Magenta, White, Silver and Black.
$7.95/yd
I realize I might be pushing for too much weight savings, but I like to experiment and push the limits as far as I can, Given that price point, I figure I can cover the boat for about $55. If I use some neoprene repair tape (double sided) to hold it along the keel and gunwales (about $15) and cover the stems with skid plate material (another 20-30) I've got the boat covered for under $100 with a relatively low labor factor. At worst, if it does fail miserably I can pull it apart and rework the fabric to make a cover for storing the boat. Then I can go back to the 'old reliable' canvas and filler method and paddle away for another 20+ years.
The boat was initially set up with a sailing rig, and the bow seat has the hole for the mast to fit through. I've seen your sail drawings years ago and may get back in touch about setting it up to sail again. I've got a few left over rudders and dagger boards from old Sunfish that may work as parts for this, but not sure how to fashion a mast and gaff rig.
Thanks,
Allen
Todd Bradshaw
Sailmaker
Repeated flexing in the same spot can promote coating delamination, but lack of repeated flexing doesn't really prevent it. If the nylon fibers eventually get saturated with water on the uncoated side and it stays that way for long enough, its a somewhat similar scenario to varnished wood. You can have the most gorgeous varnish topcoat possible, but if the wood under it remains water-soaked for very long, all that nice varnish will eventually start to peel.
200 denier is awfully light for something that might occasionally encounter being beached or set on the ground. That's pretty much raincoat or backpacking tent floor fabric. It will take a little bit of abuse (one can obviously walk on a tent floor, although the sanity of doing so depends on what's under it). Most of the nylon used for medium-budget inflatables (like Sevylor inflatable kayaks and other similar brands) is in the 600-800 denier range to give them at least reasonable puncture resistance. The premium inflatables made with nylon skins (most actually use Hypalon or Neoprene impregnated nylon or polyester, like truck tarp material instead - but there are a few with coated nylon skins) are generally in the 1,100-1,400 denier range. Of the Seattle Fabrics offerings, the heat-sealable pack cloth would probably be the best choice, but it's certainly not cheap at nearly $20 per yard. At least with the 200 denier FR fabric, if the boat catches fire, the skin will rapidly self-extinguish when the source of the flame is removed.....
...unless, of course, the wood is what's on fire
.
I still think the biggest problem will be the stretching. They do get around this with the nylon-covered skin-on-frame kayaks, but they're using really heavy nylon, stretching and sewing it in place and then coating it once it's sewn on with liquid hypalon rubber. That's a bit different from doing the skin in one step with coated fabric.
200 denier is awfully light for something that might occasionally encounter being beached or set on the ground. That's pretty much raincoat or backpacking tent floor fabric. It will take a little bit of abuse (one can obviously walk on a tent floor, although the sanity of doing so depends on what's under it). Most of the nylon used for medium-budget inflatables (like Sevylor inflatable kayaks and other similar brands) is in the 600-800 denier range to give them at least reasonable puncture resistance. The premium inflatables made with nylon skins (most actually use Hypalon or Neoprene impregnated nylon or polyester, like truck tarp material instead - but there are a few with coated nylon skins) are generally in the 1,100-1,400 denier range. Of the Seattle Fabrics offerings, the heat-sealable pack cloth would probably be the best choice, but it's certainly not cheap at nearly $20 per yard. At least with the 200 denier FR fabric, if the boat catches fire, the skin will rapidly self-extinguish when the source of the flame is removed.....
...unless, of course, the wood is what's on fire .I still think the biggest problem will be the stretching. They do get around this with the nylon-covered skin-on-frame kayaks, but they're using really heavy nylon, stretching and sewing it in place and then coating it once it's sewn on with liquid hypalon rubber. That's a bit different from doing the skin in one step with coated fabric.
