Jay-T wrote:
I am getting ready to buy a back-up battery and battery case for a
13-foot aluminum boat that I have. The battery will be for the
electric trolling motor. The reason for the second battery is for use
if the first battery starts to run low and so that I will be sure to
have enough back-up power to use the trolling motor to get back to the
boat launch area. The boat also has a gas engine, but it is a rope
pull-start type so the battery won't be used for starting a gas engine.

I'll probably go to West Marine or someplace similar to buy he battery
and battery case, and hopefully they will be able to tell me what type
of battery to get. But, just in case they don't know or they give out
wrong information, I thought I'd check here to see what people
recommend that I look for and buy.

Thanks.
If you just want a decent deep cycle go to Walmart and pick one up.
IIRC, there are only a handful of manufacturers making conventional
lead-acid batteries but they have many private labels. If you want to
spend some bucks for the latest, and greatest, look at the AGM's and Gel
Cells.