Hi Rick,

You really, really, really want separate finish lines here.

Plan A: The safest thing to do is set up a mark boat positoned as a finish boat at the orange C mark. That will ensure complete separation and maximize safety for all. EDIT: It is best for the orange C mark to be a gate for this to work correctly, otherwise you'll have a potential for boats to be rounding the mark to port while others are trying to do a downwind finish. Tie the mark boat to the starboard gate mark for the finish line.

Plan B: Have the yellow course boats finish on the starboard side of the signal boat, and the orange boats on the port side. This would help if you're short on power boats. You'll need two people calling the finish. It would help to make the starboard finish pin yellow, and the port one orange. Then you can just tell the sailors to pay attention to their mark colors.

As a separate note, I wouldn't bother with the yellow B mark unless you have an abundance of mark boats, or an extremely steady wind. That's a lot of stuff to move around when the wind shifts.

Mike