Re: Battery cables
Well, if something says "Marine" on the label, it's double the price. For some things it makes a difference. For others it does not. Another good example is fuel line. Go to the marine shop and price it by the foot, then go to your discount auto parts place. The auto parts stuff works just fine, and I've had it on my portable tank for over five years.
Same thing with stainless fasteners. Compare prices at the marine shop and your local ACE hardware store. Yikes. It's always worth checking to see if someone other than the marine shop has an item. If there's a farm supply place near you, it may have even lower prices.
OTOH, for i/o engine installations, the stuff under the doghouse does have to be labeled "marine."
Boat$ are expensive, it seems.