Pull their key out of their boat? I can understand if it is docked or moored somewhere, but if its trailered? Why? I have never forgotten my key, because its where it goes, in the ignition. No one is going to steal your boat because the key was left in it. Thats what trailer locks are for. Keys are not going to fall out of the ignition when traveling. You have enough to worry about when boating, remembering the key should not be one of them.