Re: Paddle wheel Houseboat restoration
Hmmm... looking at all that rust, I hope you sandblasted it out, checking for thin hull plates and replaced what was corroded. I'd hate to think you had plates that would hold water but not stand up to impact of any kind.
You can in fact patch a steel hull in the water. It's possible to weld in the water, although it's a specialized skill and will cost a fair bit of cash to hire someone to do. If a leak developed I'd personally just plug it from the outside with a "soft patch" IE boards and plastic or similar. Then you wait until the inside dries and patch the hole from inside with a piece of steel. You can use a material like 3M 5200 on the outside to seal the hole. Then you wait until you can beach the whole thing to do a permanent repair.
Or, there are tricks you can pull depending on where the hole is. If it's in a chine area or on the side, you can maybe arrange to get the hole out of the water long enough to weld it. You'd need a big lift bag on the side of the boat under the hole... any hollow item like a big fuel tank, a series of 50 gal drums, or whatever would work... you basically use them to raise that side of the boat up to get the hole out of the water. You can also lower the other side of the boat via weight, cables to anchor blocks, or whatever. It's tricky, basically you're inducing a big list to get your hole dry long enough for repairs.
Big ships have been repaired in the water a long time, so there are a lot of ways to fix metal boats in the water. I'm betting you'll find out that most of them are more hassle than just taking your best shot at leak fixes then pulling the boat again if needs be.
On the bow thruster, there are a lot of types. The cheapest is a big trolling motor on the bow with a remote control at the helm. Most of the commercial units run on either electric power or hydraulic. The big ones in ships have their own motors. Basically these are props mounted across the beam inside a tube that penetrates all the way through the hull. For your use I don't know exactly how you'd do that, maybe mount the thruster tube externally on the bow under the waterline.
Any reason you can't put the boat in the water to check for leaks, and if it's good then start building the interior on the water?
I wouldn't put the interior in until you're 100 percent sure it won't leak....
Erik