Battery recomendation

[oldfielder]

Unless you are in a bind, never leave it turned to both. One battery will always sap the other until you basically have one big cell at the same level of discharge and your worst case scenario is that you wind up with up with two dead ones, especially if you are on a long, lazy fluke drift out in the ocean on a nice summer afternoon.
Get a starter and a deep cycle and dedicate the starter to the motor and the deep cycle to your electronics, etc. They are very different batteries designed for difft. purposes. I invested in a combiner/isolater a few years ago and it gives me a lot of piece of mind for the $100 I spent on it. I now basically leave the battery switch turned to 1(starter) all the time when running, but the house battery also reaps the benefits of being charged. Talk to the guy down there about it. It's a very easy thing to wire up on your own.
We'll have to tip a few down there some time.