The reason you need insurance is that if someone is injured at one of your tournaments, they can sue the tournament officials and club.

For example:

Someone (Boater A) in your club tournament hits a swimmer and kills them. The family will sue Boater A and also the club officials (including the president which most likely will be you).

Boater A's insurance will cover Boater A, but no one else. All club officials will be left without any coverage. Even officials with boat insurance will not be able to get help because thier boat was not involved.

Also, unless the swimmer has signed the waiver, they can still sue. So obviously they don't help at all.

This has the potential to financially ruin you.

That is why insurance being coverd by the BASS Federation is such a big part of the OBF Clubs.