I have dropped kayaks. Many kayaks, under my charge have been dropped. There was the wooden one, made by Fox Lane Boatworks. A beautiful boat. I dropped it from a roof rack onto pavement, unloading the boat from my roof. It bounced on a cold winter morning, and I commented on how durable the boat appeared to be. At the time I was trying to get work instructing for them. I didn't get the job.
I don't know how many fiberglass boats I dropped on rocks while moving them on NOLS courses. Fewer than the students dropped, that is for sure, but I have definitely dropped my share. Generally from about knee height, so not that bad. Fiberglass does pretty well when dropped. But I have done some repairs post course with NOLS. Mostly small cracks, no big deal. (On a side note, if you want to test gear give it to NOLS. I worked three courses one summer and destroyed a brand new TNF sleeping bag. 90 days. That was its life)
I have paddled a lot of traditional plastic boats as well, but I never really worry about them. You could probably run your rotomolded poly boat over with a truck, kick out the dents and go paddling.
The boats that live in my back yard are close to the house on a home made wooden rack. Directly next to them is a tree that is probably 3 feet in diameter. My thinking is that they would be protected should something unfortunate happen. But about a week ago we got a night of big wind. The following day I went back there to check on things and I found this.
I have had people look at thermoformed boats, and for some reason decide that they look brittle. Meaning easy to crack. I have dropped my delta from knee height and done zero damage. I have had an 800 pound bear stand on the back deck of my kayak and cause no damage - I was hoping for claw marks! After the bear I slid my Delta down a 40 foot rocky beach to the water, while we carried Sarah's fiberglass boat. Yeah, it got scratched up. But it is fine. But when I saw the scene above I got nervous. We need this boat for AGAP 2014, we don't have the resources to replace a boat, and I have just completed extensive repairs on another boat. I don't want to do that again. But when I got up close I was amazed. First, the branch that fell in the windstorm was about 10 feet in length and about 4 inches across. It weighed around 25 pounds. There was zero damage. It fell from a pretty big height. I am not sure exactly how high, but at least 20 feet. That is a lot of force.
Now clearly, if I just spent time repairing a boat, they can be broken. The Delta I repaired was damaged in shipping and I think one of two things happened to it. Option one is impact from a fork lift. The other option is that a loaded pallet fell on it. My confusion on that situation is that the damage was pretty extensive on both sides of the bow. I suspect a great deal of force was dropped on the deck of the boat. There was probably just nowhere for the force to go. But that situation whatever it was, was out of the ordinary.
In my experience is rotomolded poly boats are the most durable, But I think thermoformed is a close second. Take a hammer to a fiberglass boat and see what happens. Of course, Fiberglass is easier to repair, so at the end of the day I don't think it makes that much of a difference. I think most of the big boat companies make incredible products. But don't tell me Thermoformed isn't durable.