An important component of said houseboats is the new houseboat control port. This port, similar to the mailbox and dustbin, is automatically given to you and can be placed anywhere, but not duplicated or deleted. This control port is very important as this is the only way in which you can move your houseboat. To move your houseboat, simply click on the control port and choose "Move Houseboat". You will then be taken to Map View, where you can click the point of interest that you'd like to visit (provided it's in the water).
A glitch with houseboats is Sims will do a lot of teleporting. If your Sim has to work, he or she will teleport to the carpool outside your dock because carpools are land vehicles.