Thanks Maine Sail. I just stopped by the boat, and found some interesting details:
First, the current alternator "out" wire appears to be a #10 AWG, and it wraps around the block, and then connects to the starter solenoid. From the starter solenoid, there's a 1 AWG cable that goes to the battery switch on the center post.
Is there any good reason why the alternator would go through the solenoid, or was this more likely a matter of convenience with the wiring harness?
Second, my alternator is only 75 amp, not 90. Though by Blue Sea chart, that's on the line between 4 AWG and 6 AWG, so might as well go with 4.
Third, I can't find a ground wire attached to the alternator that runs back to the ground. I can find a couple wires that supply ground to other things like gauges and the voltage regulator, but it appears that the Balmar is grounded by its mounts. Is this even possible?
If this is getting too far off the topic of fuses, please let me know and I'll start another thread.
1984 Sabre 34 Mk I