In our game the GM uses several alternate ways of gaining and losing Crew Moral which I thought I'd share.

The most obvious is VICTORY! Victory always boosts moral, on land or in space giving the other guys a good thrashing is always grand! Even when losses are severe, the survivors can point to the corpses of the enemies and drink to their lost comrades who have been avenged. Another slightly smaller version of this concept is succesful competitions... beating the opposition in a race to the best bearth is worth a few cheers. Successful gun drills can also be great for moral - seeing their cannon blow apart an Oort cloud object always fills a crew with pride. Similarly uncovering a great treasure or achiveing a goal should also boost crew moral - after all they have been part of a great endeavour which they will be able to tell the tale of when they are old and grey (if they live that long!)

The downside to this is of course DEFEAT, being beaten in a race or not achieveing a goal... Not only have they failed, perhaps their comrades died, they may be branded as cowards and may even suffer puishment.

In the Aubrey/Maturin novels; Captain Aubrey mentions quite frequently the importance of crew moral - nothing binds a crew together so well as a winning battle, failing that a great storm or the joy of gun practice!