Anything without covers in the tropics will deteriorate in a year or 2. The rub is that even though you need to cover things, if you keep them covered for a month or two you have green growth from humidity. Probably doesn't happen on the sea but when you get to Southern Mexico the humidity will cause problems. Still, better to cover it as the green comes off, deterioration doesn't

You might consider getting one of those small air conditioner/dehumidifiers that have the flexible vent allowing you to put it inside with the vent going through a hatch. LG has one that's pretty nice and is fairly small. It's unbearable in a marina without one.