I'm looking for a sci-fi book about a female pilot/magician. She had 2 husbands; one was also a pilot, the other was the mechanic for the engines. They tune the hulls of the ships to various musical notes and navigate by reading tarot symbols in space. They are looking for the lost way to Earth.
I believe you may be looking for Five-Twelfths of Heaven (Roads of Heaven, #1) by Melissa Scott.
In a space-faring civilization where a single woman is increasingly disenfranchised, the star pilot Silence Leigh is defrauded from her inheritance by a greedy competitor. Forced to ally with two men, Silence is dragged into a deadly political struggle, and is tantalized by the hints of the legendary Earth, as well as the dread and the glory of Magi's power. Her dreams of having her own ship and of escape from the Hegemony's oppressions take on new direction and focus when she joins the crew of "The Sun-Treader"
The hull of the ship is tuned with a harmonium to travel through space:
The essential parts of a starship were the sounding keel and the harmonium. The keel was made of a base metal impregnated with the Philosopher's Tincture, the only celestial substance that could exist in the mundane world. The tincture in the keel always sought to return to the transcendent, nonmaterial world--heaven--beyond apparent reality, but was bound down by the material substances with which it was surrounded. Only under stimulus from the harmonium, which was tuned to as close an approximation of the music which ruled heaven as was humanly possible, could the tincture rise toward heaven, first fleeing the elemental earth of a planet's core, then rushing faster and faster into the void between the stars, where the barriers between the mundane and the. celestial were thinnest. The rest of the ship, riding on the keel, was drawn up with it.
The lady pilot is Silence Leigh. The two husbands are Denis Balthasar and Chase Mago. Balthasar is the owner/captain of the ship and Chase Mago is the engineer.
Silence has discovered a lost route to Earth in an old book:
Silence smiled, suddenly calm, knowing that she held the answer to the one question that would fascinate Isambard and save them all.
"I know the road to Earth, Isambard. I will take you there."
She was aware that Balthasar was staring open-mouthed at her, and then she heard him mutter, "That old book. Of course," but she could not spare the time to nod to him.
This is the first book of a trilogy. The other two books are Silence in Solitude and Empress of Earth.