But when it’s incidental and minimal, …
– Last Updated: Sep-17-15 9:58 PM EST –
... you can ignore it.
Consider an eggshell. If you could coat your boat with eggshell, it would crack when the hull flexed, no matter how slightly it flexed. Yes, the eggshell would absorb energy when it cracked, but is it enough to matter? I say it's not. Gel coat is more flexible and a little stronger than that, but its flexural strength is still miniscule in comparison to any material from which a hull would be constructed. The stress it takes to make a paper-thin layer of gel coat break when flexed is so slight that you can (and should) ignore its contribution to strengthening the hull (or protecting it via energy absorption, as you prefer to say).
Using your logic, the paint on your car helps protect the metal when that metal is stressed. After all, the paint cracks if the metal bends more than little, so it must have absorbed energy, right? Well, you are right, but is it enough of a contribution to matter? Does your car benefit from the paint when you have a minor collision?