^^ True. There are any number of sketches and I feel reasonably sure we've seen only a small percentage of what MJ sketched. It's been said often that he made "hundreds of sketches" before he settled on a concept he liked for their hero ship and proceeded to flesh it out. It's possible "hundreds" is an exaggeration, an embellishment, but even so he could have done numerous sketches of which relatively few have been seen publicly. A sketch for the Valiant
could conceivably be buried among sketches we've never seen or a disregarded sketch could serve as a basic concept to come up with a finalized design for the ship.