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Alternator for 310 (2003)

Feb 6, 1998
Canadian Sailcraft 36T Casco Bay, ME
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
2 Old Pirates
PS. Here is a new diagram, input is appreciated.
1- If you install an ACR there is no need to run the charger output to both banks, just to the house bank.

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?

Ward H

Nov 7, 2011
Catalina 30 Mk II Barnegat, NJ
Generally speaking the 7610SI ACR is a good choice
I followed Maine Sails recommendation when I bought mine. I was going to buy a cheaper one but Maine explained the SI has 3/8” studs and the start isolation feature. Convinced me.