Development

The story for The Search for Spock required several ships. The Grissom was investigating the Genesis Planet, the freighter that is attacked and destroyed by the Klingon Bird of Prey (originally supposed to be Romulan), and the Excelsior that was supposed to chase the stolen Enterprise but fails thanks to Scotty's sabotage. All the models were reused frequently. Perhaps none so much as the Bird of Prey, but in close second was the Excelsior. There were a lot of designs put forward for what it should look like. Bill George at ILM was charged with producing a quick physical model of each design for Leonard Nimoy to chose from. He finished quickly and created a couple of designs of his own. It happened to be one of his designs that Nimoy picked.

The other designs are a great departure from the Enterprise design by Matt Jeffries and Bill George's design seems much more familiar while still looking very different. In an interview, he said he was inspired by Japanese animators. He imagined how they would have designed the Enterprise and made that. The unused designs found there way into Star Trek as background ship in a space junkyard. But you can see the influence of these designs on the Grissom, which has very similar warp engines.