hey, if I understand you, you're training for an upcoming bike ride from Chicago area to Niagra Falls, but you'll be on a 40' sailboat around the Florida keys for a while and want to maintain your fitness while on the boat. First, I'm just a bit envious, to be honest. Second, good luck with your fishing. Third, I'll make a few suggestions about maintaining fitness on a boat. I'd recommend a jump rope for cardio. Another cardio would be "Up-downs". Up-downs is an exercise where you begin standing, drop to a track sprinter's starting position (squat low with hands in front of you touching the ground), transition in one move to push-up position, do one or two push-ups, move back to the track starting position, and then pop up on your feet. This is normally done in cadence, like 1-2-3-4-5-6, and in sets of 10 or whatever repetitions, also in the cadence. For leg fitness, calistenics like lunges and scissor-kicks, step-ups, mountain-climbers, and there are so many other calistenics and also abdominal/core exercises that you can do on the deck of a boat to maintain your fitness, maybe using a foam mat without any equipment. Maybe this works for you or not. Anyway have a good time!