Quick Question
 

Over the winter do I need to take out the sub or amp in my boat or would it be okay to stay?

it can stay. unless you plan on your boat getting fillin with water or something.

Amps
 

At Walmart and Target they sell a package of dehumidifying powder. It goes into a container and absorbs water that is in the air - assuming that your boat is covered. I think I paid $5 for them.

My boat is covered and outside, amazing how much water it aborbs

Depends where you store it and how much humidity is in the air. The sub in an enclosure isn't as much an issue for me as the amps are. I keep a small fan on low pointed at my electronics to keep air moving and stop corrosion from forming caused by the condensation in colder months. As long as the air is moving condensation shouldn't form. I also keep a couple tubs of dessacent to pull the moisture out of the air in the boat.

cat litter in old coffee cans does a good job of absorbing water in the air as well and is super cheep