Not really a fan of bow bumpers. They deteriorate pretty quickly (within a season of regular use) and are only effective for very slow speed collisions.

I've seen Vagabonds (slow speed training dinghies), Pacers (higher speed teams racing dinghies) and model yachts all get holed or get significant damage after a T-bone with the same boat, both to the "T-ee" and "T-er". All had rubber bow bumpers.

Better to reinforce with learners to keep a good lookout and not run into anything. That concept will hold them in good stead for the rest of their lives, as opposed to relying on bow bumpers.