Non-Combatants — Alexander Fullerton

 
A young merchant marine embarks on a deadly voyage across the Atlantic in this WWII naval thriller.

Summer 1940. Merchant Marine Andy Holt is second mate on the SS Barranquilla, sailing from the Clyde to Cuba. With a pregnant sweetheart waiting at home, he hopes to make it back in time to get married and welcome their child into the world. But odds are against any individual ship getting over the pond and back.
There have been heavy losses off Norway and Dunkirk. Now the vital priority is for escorting destroyers to counter the invasion threat. Though the outward journey may be perilous, it's the homeward trip where the real danger lies: U-boats prefer their victims deep-laden and full of cargo.