I find that skin-on-frame is most fascinating. Quite a change of pace from the "modern" way of building a boat (hard shell). It can be easy, cheap, and quick - no small feat in and of itself.

Puncture resistance depends largely on the fabric used - nylon is usually considered the toughest, and the popular 8 oz. material is plenty strong. The strength comes from the nylon fiber itself, being tough and elastic. Nylon was used for bullet-proof vests before Kevlar was developed! Polyester is strong too, but not elastic. Cotton works well, and in heavier weights (12 oz +) can be quite tough. Hemp and linen fabrics might do well, but are difficult (and expensive) to come by so few (if any?) have used them. Acrylic might work, but I have read that it will relax over time when under stress (like being stretched over a kayak frame...). Then there is PVC - typically the same material used in heavy duty truck tarps, although the clear vinyl will work too - which requires no coating, although the skinning method is different than fabric (see Tom Yost's website for all the details about PVC). I've also seen nylon-reinforced neoprene, so that might be an option.

Coating options can be paralyzing. There are a lot of things that work, although not as many that work very well, and only one is designed specifically for skin boats (Spiritline "goop", a 2-part urethane). Coelan and Zar are popular one-part polyurethanes that work very well. You can use liquid rubber (neoprene or hypalon), enamel (marine is better than typical hardware store enamel), even latex house paint, elastomeric roof coatings, or home-brew linseed oil/talc/wax coatings (on canvas). Some are not very scratch-resistant, some are; some coatings are easy to touch up, others can't be re-coated. Some are cheap (roof coating, hardware store enamel) others are very expensive (Coelan, "goop", other polyurethanes, liquid rubber). You thought designing a kayak was difficult, wait 'till you have to decide on a skin coating!

I skinned my first SOF in ~4 oz. polyester. The only time it has been holed it was off the water. I'm careful not to hit potential puncture hazards, but it does happen and it has fared well. I wouldn't risk it too much though, a heavier skin would at least keep one from worrying about it so much.

The recovery is skinned in 12 oz (IIRC) nylon, coated with Zar polyurethane, and its tough as a roto-molded kayak. I doubt I could stab a screwdriver through it with all my might, I would bet money against even a sharp knife. Last time I checked, George Dyson stocked nylon and/or polyester in weights as heavy as 26 oz. (IIRC). I don't know why one would ever need such a tough (and heavy) skin, but it is available if you need the piece of mind!

Bottom line is, with appropriate skin and coating, a SOF will be as durable as any fiberglass or plastic kayak.

: I am quickly becoming fascinated by SOF kayaks. Looks like my niece is not to
: interested in building her boat so I am seriously considering just putting
: it aside for now and building a SOF. Finish it (probably redesign it some
: too) this winter. Yea, I know. I haven't finished the Hybrid yet and I am
: looking to the next boat.

: I know that everyone new to SOF worries about putting a hole in their boat. I
: realize that they are stronger than then look. But I am trying to
: understand is what it does take to damage one. Where I want to paddle I
: think abrasion is more of an issue and that most of that can be avoided.
: Mostly smooth rocks and sandy/muddy landings.

: But some of the creeks have sharp rocks along with limbs and stumps that can
: have sharp points just below the surface. There is not much chance of
: being lifted on a wave and dumped down on top one. It's much more likely
: to paddle across or into one.

: So what can I expect?