oh.... and as for guitars on board, the solution is garage sales. Find one for 20 bucks and throw it away if you ruin it..... but you probably won't for quite awhile. With little invested, you won't worry about it. No case, just throw it in the back of the wet locker! Rusty strings .... oh well. (gut strings on a classical guitar anyone?)
I agree. Doesn't have to be a garage sale (don't normally find guitars). When getting ready for a trip last summer, my wife picked up an excellent used, plywood topped (for stability and cheapness), 6 string acoustic guitar for $50 at a music store . It has surprisingly good sound, a very accurate and easy to play neck, and came with brand new strings!
We got it for a week long sailing trip, we used a garbage bag for a "case", which didn't take up much space. On an extremely small boat for two people for a week.
I keep it in the open air on a rack at home, easy to pick up and play for a few minutes, and I don't worry about it drying out without a case. Because I don't care much about it. Little investment, lots of fun.
As an aside, I was putting on a roof in Florida once and from my height I saw the garbage truck coming. I looked across the road and saw a guitar leaning against the garbage, about to be picked up and crushed. What would you do? Yeah, and it wasn't a bad classical guitar to drive home with.