anodes

[RLT III]

i have a 81 grumman 15' alum boat and i have a anode on the motor brand new but i'm wondering do i need more of them and where cause i will be fishing in saltwater

[Faztbullet]

Can you supply the year and horsepower engine so we can assist you futher?

[RLT III]

81-83 i was told merc 50 3 cly #5797770 is the #'s on plate sq. cowling on motor and a 1981 grumman boat with a extended alum transom as well