1- If you install an ACR there is no need to run the charger output to both banks, just to the house bank.So much info. We basically day sail. We have weekend trips usually 4 times a summer (Lake Ontario). Destinations are always plugin at dock. Does this help at all?
Found out that the alternator is a Motorola 51A
Cheers
2 Old Pirates
PS. Here is a new diagram, input is appreciated.
2- If you have a 1/2/B switch I'd recommend putting the HOUSE on position #1 (primary bank ON/OFF) and the start/reserve bank on position #2. The less you "wipe a switch" the longer it will last and switching between Bank 1 and OFF, on many switches,puts the least wear on the switch wipes/contacts.
3- For your described use you could just stick with the stock alt but, charging will be slower away from the dock. If you should decide to upgrade a CMI-72-IR would be a good fit for that engine & belt, really it is specifically purpose built for those engines, and you could push it to 90A too but will have more belt dust. A key benefit of a CMI-72-IR or a CMI-90-IR is that either can be converted to external regulation in the future. So you can start with IR, and if you need it in the future, move to ER.
4- Don't forget house bank fusing at 250A to 300A minimum.
5- How do you plan to wire the alternator?