Of course your writing isn’t crap. Okay, well maybe it is to start with—everyone’s is—but it won’t be when you’re finished. Why? Because you’re an author, dammit! You care about what you’re doing. Moreover, you love it! There are fifty billion and three readers out there (exact number; documented fact). Your story will be enjoyed by some fraction of them. Some people like spaceships, some like medieval vixens, some like medieval vixens flying spaceships. I didn’t just ruin your premise did I?
In the end, who defines crap and non-crap, anyway? The great toilet in the sky? I think not. David Ball, journalist and author of Exquisite Darkness, says it well. “Never put off writing until tomorrow what the voices in your head can tell you is crap today. And don't listen to those voices.” Yes! That’s who defines crap—YOU! We writers tend towards schizophrenia, and if not medicated properly, often believe the snarky voices in our heads. Don’t. They lie.
If you’ve ever met anyone who’s read your really wonderful work, and you notice they’re looking at you a little starry-eyed, and then they tell you how totally freaked they were when that snow lizard was chasing your protagonist, Tesla, into the tar swamp, and how freaking awesome it was when she gutted it with her tanzanite sword, and that big smile blooms across your face and you feel all warm and a little “hell yeah!” inside, then you know your story wasn’t crap. It was damn good. You totally freaked somebody!
Let your spaceship story flesh itself out, then clean it up, edit, revise. You’ll get it where you want it. Be kind to yourself. And tell those voices to go flush themselves!