Thin shell Styrofoam
Posted by: rectorsquid on Oct-23-12 3:11 PM (EST)
If a thin shell Styrofoam lined helmet has an impact and the foam is compressed, that foam is no good from that point on. This applies to a bike helmet and any other helmet of that design. I have a rock climbing helmet made for head impact (vs. rock fall impact) and it is a use-once helmet. If the foam is compressed, it will never again absorb shock in that area.
I would guess that paddling helmets are made with a thick outer shell so the foam doesn't compress from most typical impacts. The one paddling helmet I have worn was that type. My ski helmet is also that type.
I just wanted to point out that helmets can vary even within a sport and the helmet design is the factor that makes them appropriate for a specific use, not just the sport that uses them.
I would use my ski helmet for paddling but it's lined with comfy stuff that won't want to get soaked. It's too bad because if I ever want to play in the surf or try WW, I'll need to have four helmets instead of the three I have now.