Cover your Propeller with a Plastic Bag
When you leave your boat in a marina for an extended stay simply dive down and put two plastic bags over the propeller. Tie them in place with a piece of string around the prop shaft.
When you return to your boat, don’t forget to remove them before you start the engines up! You will find the bags covered with marine growth, but your props will be weed and barnacle free – especially if you cleaned your props nicely before putting on the plastic bags.