Sea Legs

Doesn't look from the outside as though it would be funny, but funny it is. Two brothers are living with their father whose job takes him off on cruise ships. The boys are worried that he might find a mother for them on the next cruise, and they decide to sneak on board and protect their interests. The dialogue between the brothers is hilarious, and the predicaments they find themselves in are really good. They get off the cruise ship in Egypt and go exploring, but then when they return to the cruise ship at the appointed time, there is no cruise ship??? How can they keep their cover and maintain their stowaway status and what will they do when the ship is overrun with thieves?