It is scratch build, based on a "scudder" hull, a design by Glenn G. I printed a few pictures of Khetanna from the net and used those for guidance in the process.
The superstructure is a combination of balsa and ply wood. in the Star Wars tradition, the boat is propelled by a jet propelled engine. To finish it off, a Lego version of Jabba was added for extra detail.
It was a fun and fast project to built, maybe a dozen or so evenings.
(scratch) building is my passion and only sail the boats with my son about once a month. We've got a pond near Newcastle (AUS) harbour which is pretty good (providing there's no weed in it) but the disadvantage of this pond is salt water, meaning a proper rinse of the models is needed after each sailing session. Recently we have moved our sailing sessions as well to the liberty pond in town. The model captures the audience, the vast majority recognize the Khetanna immediately.
Happy sailing.
Jeroen