: it's interesting that the thinner polyesters used in aircraft(the 3.7oz and
: less) can shrink so much and that the slightly thicker stuff like the 10oz
: range used on some yaks here is so non strethable.

: Do you know if heavier but shrinkable aircraft polyesters are available or do
: you have an idea why the thinner stuff is so heat shrinkable and the
: thicker stuff isn't. Would it make any sense to double skin parts of the
: yak w/ thinner skin and yet maintain the shrinkability.

My understanding is that it's in the way the fabrics are treated during manufacture. Some fabrics are heat set, essentially shrinking them before they are shipped. These fabrics will have little or no additional shrinkage capacity. Fabrics that are not heat set, such as aircraft Dacron (a proprietary name for polyester), will be shrinkable.

Frankly, I've seen boats shinned with 3.7 ounce Dacron and there's no way I would trust it as a kayak skin unless I lived in an area where all the beaches are clean sand. The fabric is subject to lots of stress when used on an airplane, but it's not subject to cutting, tearing and punctures from contact with rocks, shells, logs and other flotsam. If the 13 ounce works out well, I may consider trying 8 ounce, especially if I can find a shrinkable fabric in that weight.