I've asked about boat batteries before but now we're planning to launch
next weekend and it's time to buy them. So see if this makes sense or if
I'm wrong anywhe

SITUATION:

The boat is a 22 foot 1958 Chris Craft (that we've been restoring for
the past 2.5 years). Engine is a in-line / straight 6 cylinder 130
horsepower and 320 cubic inches. It has a generator with voltage regulator.

The electrical setup I've created calls for two
12 volt batteries. They are on an A/B/ALL
switch with a battery-combiner (BC) between them.
Normally I plan to run with the switch in
just the "A" or "B" position. So when the engine
is running the BC will combine the batteries and
both will be charged. When the engine stops and
we are drawing current for light & such, only one
battery will be supplying power. If that one got
drained we could switch to the other to restart
the boat.

The items that might be drawing power on the boat
a Small bulbs for bow & stern lights, Small bulbs
and LED lights in the cockpit & cuddy/cabin areas,
Instrument back-lighting, Depth Finder. Maybe
something like a radio and/or GPS plugged into
a 12 volt outlet. Also there are two 1100 GPH
bilge pumps, but I don't expect them to run much.

Use: We are in the Northeast and will probably trailer
the boat, using is every other weekend or so. There could
be times we're on vacation with it in a slip for a week
at a time or possibly sleeping on the boat for a night
while moored near some island or something.


QUESTIONS:

TYPE OF BATTERY: I know that Gel or Absorbent Glass Matt
(AGM) are supposed to be better. But for this application
where these is not much vibration, no need to mount the
batteries in any position except "normal" and where the
battery may not get 100% proper storage (ie no trickle
charger all winter) I'm thinking the extra cost is not
worth it. I'm thinking just use regular flooded batteries.

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.

CCA/MCA: I really don't know what size Cold Cranking Amps
or Marine Cranking Amps is necessary/good to turn over the
engine I have. I'm guessing that anything in around about 550
is fine. If I can get more for not much more $$ than that's what
I'll do.

RESERVE CAPACITY: I really don't have much draw on these batteries
so pretty much whatever the RC rating is will be fine for my use.

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.

TWO OF THE SAME: Since they will be charging in tandem (together)
it's best to have two of the same. Also, I'll sometimes have the switch
on "A" and sometimes on "B" so both get approximately the same
useage pattern.

BUYING:
+ Check the date manufactured on the battery and try to get ones that are
less than 3 months old.
+ Try to get them with a longer free-replacement period as this is a good
sign of quality
+ Watch out because replacement are sometimes pro-rated and based on the
LIST price, not retail.

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


Thanks for reading and for any help or comments!
Gary