Midshipman's Hope by David Feintuch
When a hideous accident kills the senior officers of UNS Hibernia, it leaves a terrified young officer to save three hundred colonists and crew aboard a damaged ship, on a seventeen-month gauntlet to reach the colony of Hope Nation. With no chance of rescue or reinforcement, Nicholas Seafort must overcome despair, exhaustion and guilt. He must conquer malfunctions, mutiny and an alien horror beyond human understanding. And he must save lives, and take them - in the name of duty.