: I'm shopping around for skin materials for my SOF projects this winter. I've
: heard 9oz polyester, 12 ballistic nylon, etc, etc.

: Most sources I have visited don't deal with oz-weights, but are quite happy
: to discuss denier-weights. Is there an x-ref chart I can look these things
: up on?

: Also - one upholstery shop that specializes in boat tops and such that I've
: visited can sell me 11.3oz or 1000 denier cordura (urathane coated) or
: 11.5oz polyester coated with acrylic. Odly enough their catalog lists
: different weight units for different fabric types.

: Would either of these be suitable, or would anything I painted on them eat
: them? Given a choice I will lean toward ruggedness in my first boats over
: a bit of weight savings.

: Cost for either of the above fabrics would be $22 CDN (~14USD) per metre,
: 60" width.

I've gotten various interpretations of "denier". At one time I understood it to be a measure of how many threads were woven in a given area. The more threads, the denser the fabric and the heavier it would be. That kinda made sense. I jsut found a formula describing denier at a website of a company which makes backpacks.

http://www.lowealpine.com/Technology/Fabrics.asp

According to this, 1 d (or one denier) is equal to 9000 meters of thread weighing one gram.

Denier, therefore, relates to thread weight. So if you have 9000 meters of your thread weighing 500 grams, and you weave this into a fabric, then it will be a fabric that can be listed as being made from 500 denier nylon (or polyester, or whatever.

Any thread that would qualify as jsut one denier is going to be extremely fine and very light weight. Any thread which measures 2000 denier is going to be a lot thicker, and probably a lot stronger and more resistant to breaking.

What we are concerned about is the thickness and strength of the fabric, more so than just the thickness and strength of the threads used in making the fabric.

Of course you can weave this thread densely to make a heavy weight cloth, or you can weave it loosely to have a more open, lighterweight cloth, and both types of cloth could be described as being made from 500 denier fabric. The densely woven fabric would have MORE threads per square unit (inch, yard, meter, whatever) and would therefore have a higher weight.

So, the higher weight fabric made from the higher denier number threads give you maximum strength. Of course, this might be heavier and stronger than you really need, and more expensive, too, so buy according to your needs. Nine ounce fabric seems to suit most people, with some going for heavier material when they expect river snags, and others going for lighter fabrics when they want to build ultralight boats.

Hope this helps

PGJ