Where does the term “Catboat” come from and What does Catboat mean?

Entered merely not to skip a curious word, though little can be said about it.

Two hundred years ago the name “catboat” was applied to vessels of four to six hundred tons, built according to Norwegian design and used in the British coal trade, but no reason has been found for the designation and none for the transfer of the name to the small single-masted sailboat, with mast stepped well forward, used for pleasure.