The amphibious landing craft that Dennis and his friends managed to design and operationalize was the "DUKW," not the "DUWD." According to Milton Silverman who wrote an article in the Saturday Evening Post, April 20, 1946, p. 22, their idea did not meet with immediate acceptance:

"Rejected, blacklisted, pigeonholed, scoffed at by nearly every general in Washington, 'the truck that goes to sea' helped win the war only because three naive civilians wouldn't give up on it."

I've told John Mehlman that I'll be happy to sing this one to him but the tune is really the one I know for "The Good Ship Venus" and my mother now agrees with me.

Cheerily,
Charley Noble