make sure you run the boat long enough to get gas that contains the additive into the motor. I know many of us use some kind of stabilizer all the time, but for those that don't putting it in the tank is good for the gas there, but does not do much for the gas in the motor unlsess you run it long enough to get it in the carbs or injectors. I would also fog the motor as described above, change the lower unit oil, and the engine oil if it is a four stroke. Also a good time to grease the prop spines, throw a little wax on, and do any other maintance that you may need (impellers, new plugs, etc..).