Sorry for the double post. There are a few things I thought everyone who wants to build a port should know.
First of all, if you want to keep it the smallest size port possible you have to just copy an established port to your library and place that size lot and then the port on it. Otherwise, you have to have a minimum lot size of 40x40. If you have it smaller you can't place the gangway, (found in buydebug), because the gangway wants to lay down the slab for building the largest size houseboat.
Secondly, you have to have a LOT of open water once you build the long dock. If you make your dock too wide on the water or have boats sitting attached to mooring posts you won't be able to dock a houseboat.
Third, if you want to build a houseboat on the port you just built, you have to go back into Edit Town and then select the houseboat icon, not the port icon. If you select the port icon, or just want to build right away from the port, you can't. You get a message about not being able to build on water, or something like that, and your cursor with the walls is greyed out.
Last, ports in real life are pretty busy places and often have amenities for dock workers and ship personnel. In our ports we have to be very careful what we place on them because some items will cause a message saying there are items that are not compatible with a port and they have to be removed to keep it a port. Don't think to use it for a place for a bed, for instance, but you CAN have washers and dryers. I thought that was weird but could be a way to build a temporary shelter for a poverty stricken Sim. Not. The only place to take a snooze is on a lounge chair.
My port has a lot of amenities now but it was built on one of the smaller of the Mermaid's Secret island chain. There is a small lot on that island which I'm using for a "garden" lot and I wanted my Sims to be able to eat and clean up without having to go back to their boat. The port itself has picnic tables, cheap grills, laundry facilities, showers and toilets, benches and lounge chairs and vending machines for the hungry snacker, as well as a pizza oven.
