> Airplane fabrics don't usually have to deal with scratches -- whether from
> hitting rocks (not a lot of boulders a 1000 ft above the ground), or
> scraping on sand, while kayaks encounter these at practically every
> launching and landing. As a general rule, thicker fabrics absorb this type
> of abuse better than thinner fabrics. Dacron may be a great material, when
> compared to cotton, but to be a better comparison you would have to
> compare this dacron to a cotton fabric that weighed about the same (say
> somewhere in the 3.5 to 4 ounce range).

> As a reference, denim is in the 10 to 12 ounce range, and a fabric that
> would be a bit less than half that weight would probably be suitable for a
> dress shirt. Fabrics this thin just don't fill me with a lot of confidence
> ! However, when you add a nice thick coating of synthetic rubber or vinyl
> these fabrics may be great reinforcements, and highly durable.

> The rating of 130 pounds per square inch is not one that fills me with
> glee. Some of the more ample (10 to 15 ounce) nylon and cordura fabrics
> have ratings in the thousands of pounds per square inch, and I think the
> 20 ounce nylon I've seen is rated at well over 10 thousand pounds. How
> they measure the tensile strength is unknown to me. They may be using
> totally different methods for these fabrics, which would make comparison
> of these number irrelevant. (Heck, I'm still trying to figure out why it
> is so hard to break 5 pound test fishing line -- and if someone can tell
> me how people manage to catch 20 and 30 pound fish with this stuff I would
> appreciate it!)

> Well, now, here is a design choice. If you are going for extreme light
> weight you not mind compromising on fabric life. If replacing a more
> fragile skin does not impose too much on your time or your wallet, then
> the convenience of an ultralight boat made with these materials may be
> greater than the additional weight of a boat made with heavier materials.

> Once you have the frame, most of the boat building work is done. I'd
> suggest experimenting with the lighter weight materials. If the
> lightweight stuff is not durable you are going to need to replace it. At
> that time you can go to a heavier fabric. As long as the frame is intact,
> it is an afternoon job to strip off the old fabric and put on a new skin.
> Waiting for the coatings to dry takes a bit longer.

> Good luck with your boat. If you haven't cut the frames yet, sometime this
> week I'll send along some newly-calculated graph points that may make
> cutting these simpler, and cheaper. Putz makes his about 30 inches high,
> I'm making mine much shorter to save on plywood.

> Paul G. Jacobson

Paul; You don't just catch a 30 lb. fish on 5 lb. line. You learn how to really fish. This is real fishing. You play with them and let them run themselves till they only have 4.5 lbs. of pull left in them and you net them.

Couldn't let this go by, as it's one thing i so know about, now back to boats.............

Rehd