I have experience with 50′ houseboats at Lake Powell. I’ve heard of 75′ houseboats, but 100′ seems unmanageable. The fuel consumption numbers claimed are ridiculous as mentioned by others. A 55 footer gets about 0.5 mpg running both small V8′s at 2500 rpm for about 8.5 mph – about 17 gph. You could save perhaps by running slower, but at 2000 rpm we went only 6.5 mph. (GPS units are great for this type of experiment.)
An old school 50 footer with two 60hp outboard motors would get about 1.0 mpg.
Solar panels won’t come close to powering the needs of a houseboat, especially with air conditioning which is typically required in the southeast (warm with high humidity). The generator on a houseboat is 7.5KW and up. It takes a large area on the roof of your house to get that much out of solar panels. There just isn’t room on a houseboat for the number of panels you’d need. In a week at Powell the generator fuel usage is dwarfed by the fuel used to move the houseboat about 60 miles total, so solar panels are a hassle just to make a “statement”, and another system to cause problems.
