There are several issues: 1) damage to the axles and bearings when members stand on their tramp to rig the boat while it is on wheels. Unlike personally owned wheels, our wheels are subject to the use and abuse of as many as 50 people in the course of a day - it is hard to imagine what some people are capable of doing to a set of wheels. We purchase a few new sets just about evey year and have a wheel captain who has to spend several hours a week repairing and maintaining the wheels. 2) The experience level of our sailors varies from newbies to national champions. Twice in the past, we have incidents where a boat was being rigged on the wheels, and a gust came and pushed the boat along on the wheels and the boat flipped, hitting people in the head - twice we had to call an ambulance to render medical assistance. Luckily, the injuries were not serious. 3) People also leave their boats on the wheels with the sails up and and go and eat lunch or whatever... again, we have had squalls and gusts come through and flip boats that were sitting on wheels with the sails up - this also has happened more times then I care to remember 4) and finally, other people are waiting to use the wheels to move their boats - if they are under your boat while you rig for 20 minutes, they are not available for use by other fleet members. The easiest way to deal with this is to simply require that you do not rig your boat on the wheels.