I'm not sure if you've done this yet, but maybe try having him meet with the committee and tell him politely but frankly what's written above? Explain that bc of the complaints and concerns, he's facing suspension/expulsion. Offer that if he wants remedial instruction on the rules or tactical help on the course, someone with the committee will teach him rules and/or go out sailing with him to coach. Follow through if he accepts. If he refuses, then impose a clear fleet-wide disciplinary process. Run him through the steps (warnings, suspension, expulsion) being sure to do same warnings etc for anyone else.