How many boats does Gibbs build?

So, far, I think 2.

He has talked about burning at least one (The Diane) after that marriage failed. But this also suggests there may have been others that suffered the same fate.

There was the one he was building during the early seasons that disappeared somewhere. I don't know if that one had a name.

Then he made some furniture and toys for a while until he built and finished the Kelly. It was gifted to Mike Frank's grand-daughter.

He is currently working on the chickadee, cincia bigia - a full scale version of a model barca he made with his father when he was a little boy.

So the answer is, at least 4 but possibly as many as 6. 😀

4!