Whitewater kayak materials are broken down into composites and plastics. Rotomolding is often utilized for optimum strength. Crosslinked is known to have good shape-retention and warp resistance, but is harder to repair. Linear polyethylene is rigid, more easily repairable and recyclable. Fiberglass, carbon and Kevlar are generally reserved for racing, competition and squirt boats.
Composites are light and easily repairable.
Volume in whitewater kayaks fluctuates as much as volume in a river. Where volume is concentrated is often more important than the actual number. Total finished weight of the boat from the manufacturer. Manufacturer's suggested retail price.