I don't think that Sizzler catamarans have anything to do with aluminum construction for big boats. It's not a valid comparison. Sizzlers probably "rotted out" because of electrolysis between the aluminum and the stainless "O" ring around the joining of the two halves of the hulls. After 20 years, I'm sure the rubber barrier between the two metals disintegrated.

Here is one web site I found with some information about aluminum boats. http://kastenmarine.com/aluminum.htm

One thing I have always wondered about with metal boats, though, is how they react with lightning. I mean, the whole boat is basically grounded; right? So you don't need to put in a grounding device; right? But is the boat more likely to
ATTRACT lightning because the whole boat is metal and grounded to the water?