My bike is a fixed gear Specialized Langster road bike.
It has traveled far with me. I crossed an ocean with it aboard pino. I've cycled with it in japan, the US West Coast, Mexico, Cook Islands(I cycled around Rarotonga), New Zealand, and Fiji. The bike could have seen more roads, but not all ports had good and safe roads.
Does the bike rust at sea? No, my bike doesn't rust, the frame is aluminum and I keep the steel chain and hub well-oiled(3 in 1 oil).
Where do you keep your bike?. When in port for a long time, I keep it outside, locked to a strong point on the boat. When I move the boat, or during the winter/rainy season, I stow it inside. I stow the bikes inside in either the v-berth, or quarter berth. The best way to stow it is to take both wheels off, to remove the pedals, turn the handle bars sideways, and to tie all components with straps. I cover the bikes with a bike bag.
The bag is nothing special, but allowed us to carry them with us aboard trains while in Japan.