actualy, the boat would be a good idea. as long as you know how to deep sea fish, you would only need your initial cache of bait, then you could use what you catch as the next bait... and i don't know if it's true, but I heard at sea is that the water in a fish is drinkable.

also, being out to sea, with no shipping lanes, will actually make the chance of running into another vessel very slim.

More so with bodies swiming in the water with no sonar.

also, if your able to make a fire, i guess you could purify the water via evaporation in a beaker system. then again, fires on boats are a bad idea.