Huh, I didnt know the 505's used rabbit starts in regattas.

505 have one person on the wire right? So you have one person trapped out, crossing the stern of a POWER boat? That doesnt sounds safe. Especially in light air, when the lead rabbit is moving slow.

I guess it keeps people from being early, they dont want to run into the prop of the power boat.

The windsurfers use a power boat too, but that boat is moving at full throttle, it doesnt seem fair on a long start line, it would seem like you always want the port end of the line to get across the line first, no matter if the line is square.