>>I keep seeing in the paper, ads for marine batteries. Aren't these
>>deep-cycle types, used for electric trolling motors etc.? Why wouldn't
>>they work as auxiliary batteries in Westies, to power the stereo,
>>lights, fridge etc. when stopped?
>
>Too big (tall) to fit in the standard battery compartment.  Should fit 
under
>the rear seat though.

Nobody makes a shortie, to fit under a bench seat in a boat maybe?