Called Jim, owner of marina.
He has 3 or 4 18" ball buoys we could have for the 2 marks and the gate. May need some cleaning and paint.
Recommends at least 100 feet of 5/8" rode and garden hose at the weighted end to protect the braid on the rope where it ties to cinder blocks or whatever we use for weights.
Not sure how we get them out there or lower or raise them... how long would they stay on station as well?
Checking back with him this Friday to collect the ball buoys.