It is, but I would go with a larger capacity battery, fuel is expensive nowadays,You could get a larger output altenator, but they are expensive as well, now you don't say if the boat is MPI/EFI, If you dont have enough power to supply the main ECU (computer) you wont be going anywhere, they require a certain amount of power at start up and if it's not there NO GO, Think of it this way 12+ volts for starter, plus 12+ volts for ECU,plus any accessories you happen to have on and already your in the negative, hope this helps.