That is really good information...I know they say they're strong, but I haven't tested mine and I'm not sure I'll be in any big rapids anyway. My concern is that I like to do trips in canoes in a very rocky area in canada and I've been timid about smashing my night heron into rocks and stumps (mainly rocks). I used 10oz glass inside and out on the hull, with an extra layer up to the start of the chine (football shape)....which I knew was probably overboard, but knowing how your 6oz performed I should have no worries at all. I'm going to embark on another kayak in a month or so and attempt something much lighter, but it's good to know that even one layer of 6 oz holds up so well.

: Just as a matter of interest for those who wonder how strong a strip built
: hull is I have some recent observations. I have a 28" X 16' kayak,
: full 1/4" strips, 6 oz. cloth inside and out with a 3" wide
: strip down the keel line. On recent practice runs for a marathon race I
: have hit a cypress tree dead head on at about 7 mph with swift current. No
: damage at all except for a slight 3/4" discoloration. On the same
: trip I hit numerous rocks, dragged across rocks, lowered the boat over a
: dam with a rope and then let it fall on the ground. In one set of rapids I
: hit a rock that did make a 1/8" puncture through the fiberglass and
: slightly gouged the wood. On another rapid I hit hard on a very big rock,
: put another 3/8" puncture and split one strip about 1/2". No
: damage at all to the inside fiberglass. On the second trial run I did much
: better though I did get crossways in some very swift water and slammed
: into a stump just in front of the cockpit on the right side slightly below
: the sheer line. This punctured the fiberglass, broke one strip and split
: that strip about 1 1/2 inches on each side of the puncture. I want to
: point out that both strips that split were flat grain...not vertical
: grain. There has been no damage that tranlated to the inside of the boat.
: I'm happy with the strength. The abrasion and puncture resistance could be
: better. On the next boat I'll add a another layer of 6 oz. S glass on the
: bottom of the hull up to the sheer line and see how that works. I also
: want to point out that unless you are going to be doing what I'm doing the
: standard layup of 6 oz. E glass should be adequate. Robert Pruden needs to
: use kevlar, carbon fiber, e glass, and s glass...and maybe a little dynel
: here and there.