You are right ,mine has a small gap too . I never noticed it before. I guess you could seal it up if you were worried about it . Mine is never on the water long enough to get wet . It gets airbourne pretty quick . I havent noticed any water inside but then I never take mine apart . You have a really good point . That is something to watch . I think I will seal mine somehow . Have you done anything to your GP Cub ? What do you have in it for a motor . I have a OS fs81..