Before builing my S/G "SEGUIN" I aws very interested in the strength of kayaks built by diferent methods.I recently returned from a week of paddling the california coast and was VERY impressed by strength of my kayak.At one very steep beach where the waves were 5 to 7 ft. and dumping dumping, a wave popped the skirt and filled my cockpit, I couldnt punch the next wave and exited the boat.The boat was loaded for a week of padling so it was heavy.All I could do was to get out of the way and onto the shore and from there watch as the kayak aws repetedly(five times)picked up by each wave and dumped down again (the kayak was parallel to the shore) at one point the boat was thrown sliglly askew so that one end hit the sand before the other end did,making it wash up the beach were igrabed hold of it.I continued on my trip and my boat is just fine no cracks or any visible sign of damage. It is built of 4mm marine ply with one layer of glass inside and one on the bottom outside.