Originally Posted by Theophilus
Sometimes you just take a hell of a head shot and no matter what helmet your wearing you get your bell rung.
That is what I came to say. This is particularly so if you are hitting near the edge of the helmet. It has less opportunity to spread the impact, resulting in force concentrated in a smaller area and OP getting a goose egg from a hard hit.
The WRSI is not thin compared to other water helmets. Water helmets are thin in general. So is a Sweet.
Water impacts tend to be low speed versus say skiing, motocycling, or bicycling. There is a much greater danger of multiple impacts in water. That is why you see thin helmets with EPP that are multi-impact rated.
WRSI does this with a dual layer hard shell with two foam layers.
Sweet makes a good helmet too, but I don't see it really being more protective than a WRSI. Lighter, yes.