I'm thinking about this because something about it seems intuitively wrong to me, but I can't put my finger on what it is yet. I guess if you blow that fuse you'd still have your earth ground, so you wouldn't suddenly start using alternate paths to ground (such as through a shore side telephone line), you'd just lose the ability to charge/discharge the battery. Still, trying to use the starter after that fuse has blown is going to fully load your solar panels, alternator, etc, ????After a survey it was suggested I mount a fuse on the common negative wire very close to the batteries. The surveyor thought 70 amps would be about right. While I do not want it any bigger than required if the starter motor should blow it as the motor starts then it will fry the alternator as it will then be running without a battery. I'm thinking about using a 100 amp fuse. Can anyone provide advice on the max. starter motor draw for a 9.9 4-stroke ?