SIZE will be group 24. I believe the space that I have
for the batteries (under the passenger seat) will take
two Group 24 batteries.

Make sure you allow sufficient room for battery boxes, and go with the largest
batteries that will fit the space you describe. If you can use Group 27's, that
would be better.


TYPE: I'm thinking that Dual-Purpose is the way to go. It is possible
that I'd draw a batter down when occasionally sleeping on the boat
overnight and Starting batteries don't like that very much.

Why not just go with deep cycle? That way you're more likely to get the heavy
plates that will stand up to severe discharge. A deep cycle battery is "dual
purpose", in so much as that if the CCA rating is sufficient for the engine you
will do
*no* harm to the deep cycle battery using it to power the starter. As you have
already determined, you will damage a "starting" battery with a series of deep
discharge cycles.

WHERE TO BUY:
?? CostCo ??
?? Specific Brands to look for OR avoid ??



I like my Rolls batteries a lot. Surette is the same battery, but made on the
other side of the US/CAN border. Ten year warranty, with the first seven years
non-prorated, full replacement.

OTOH, you could afford to buy cheap batteries a few times for what you'd spend
for Rolls or Surette. Pay now, or pay later.......but if you only intend to
keep the boat a year or two before trading up the average quality cheapies are
probably the way to go.