I can't swim, either, but I have not minded being on boats.
Planes, however, I am very afraid of them. I habe been on one once, to and from for Woodstock 1999. It was okay, but I have never liked the idea of planes.
Agreed, car crashes happen a lot, and you have a higher chance of getting in one. But you are much more likely to SURVIVE a car crash than a plane crash. Of all the plane crashes that have happened, how many people actually survived?
It also boils down, for me, to trust. On a plane, I have to trust someone else with my life. Boats, too, but at least I have room to move around and be able to do something. Driving, I am in control of my truck.
Every year, I drive to Atlanta from Miami for DragonCon. I have more control of time this way. If there are weather delays or other reasons, a plane trip will be delayed, and can potentially delay to a point of a day or more. Driving, I do have to wake up very early, but at least I am getting there when I predict it. I have more control over the trip.
(Plus, up until at least the middle of Tennessee, it is actually cheaper for one person to drive than fly. Even more so when more people go.)