I use these:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Used Babz for a season but popped one and they are a little too flexible for my taste I still could hit the dock or another boat if a big wave came by as they would just flatten like a pancake with enough force.
These are much thicker and are a true buoy and not a bouncy toy.

They are big and they are firm but they work! I keep them inflated year round in the rear locker. If we need more space (we almost never do) we just hang the from the sides of the tower for the day.