: Putz's book calls for 10 oz canvas to skin the Walrus.
: Is there a way to tell what weight the canvas is, if the sales clerk at the
: Fabric store doesn't know ??

I believe he calls for #10 duck, which is about 50% heavier than 10 ounce canvas. If you are not going to hit a lot of sharp objects you can get by with 10 ounce canvas. It is relatively cheap (particularly when it is on sale ) and should last for several years if you protect it from mildew.

: There are two types on the shelf. one feels about the weight of jeans, the
: other is lighter.

You definitely want the heaviest. Levi's ruggedest jeans are made from an 11 ounce material I believe. It is probably woven specially for them, but if you could get your hands on something like that you could waterproof the inside, and not have to paint the outside. The more rough landings the more the exterior would take on a "stonewashed" look. On second thought, maybe that's not such a good idea.

The coating you put on the fabric is going to provide some additional thickness, protection and weight. Kayaks have been covered with flimsy polyethylene tarps, so the 10 ounce fabric should be an improvement over that.

Clarkcraft (www.clarkcraft.com) has a 15 ounce canvas for $7.75 a yard. That is my benchmark. If you can find something that heavy for less, definitely go for it. If the best deal by you for 10 ounce canvas is over $5 a yard I'd think twice, though. For an 18 foot kayak you'll need about 7 yards. for a 17 foot boat you'll need 6. If the 10 ounce cloth is $30 and the 15 ounce cloth is $46.50 you are talking a difference of under $17. With that small of a difference, I'd opt for the heavier cloth. Even if I was on a budget.

Now if you can get the 10 ounce for a GREAT discount, say about $3.50 to $4 a yard, I'd go with that. You are talking under $30 for the fabric. If you screw up, it is cheap to replace. If it only lasts 5 years, it is cheap to replace. If it needs to be patched every other time you hit the beach too hard, then you are not out a lot and you know for sure to replace it with a heavier fabric.

By the way, my test SOF frame was covered in 10 ounce canvas from the local fabric shop, and two coats of elastomeric roof paint. (Snow roof) This has been outside in the elements for over three years. It should have had a mildew preventative, as it has rotted away in areas where moisture has condensed on the inside of the covering. When I built that frame I meant to use the 10 ounce fabric just for a test, and then do the "real" skin from the heavier canvas.

The fabric store also had a polyester canvas which was listed as an awning fabric. It is not waterproofed, but is brightly colored and waterprepellant.They sell it in stripes and solid colors. (I got solid blue) I was thinking of using this for the deck. It would breathe and for the river and lake paddling I do I thought it would provide a suitable, inexpensive, UV resistant,deck covering. This is something I still have yet to try, but you might want to. I think I paid $4.44 a yard for it, and justified the price based on saving about $12 a can for boat paint.

Hope this helps.

By the way, have you considered dacron? George Dyson sells some stuff that is thicker than either of these canvases, and much tougher. Think along the lines of the material that your seats belts are made from! Dacron covered with a polyurethane seems to be the big competitor to canvas covered with paint.

PGJ