It was back in the late 70s, maybe more likely 80s I think, that I read this book.
The story began in Germany as I recall on the northern coast, set in the late 1900s or early 2000s. It was after a nuclear war. The main character was a sailor on a destroyer. The boilers were fired with wood because oil was not available. The ship sailed to the Atlantic to join a fleet consisting of old WW2 and Cold War ships. One was a carrier operating a motley collection of piston planes. Another was an Iowa-class battleship taken out of mothballs or memorial display.
The fleet sailed for reasons I cannot remember to Asia where it engaged another fleet, maybe off Thailand. During the battle, the battleship fired a nuclear shell into the midst of the melee, sinking vessels on both sides (very unrealistic in that those shells were dismantled in the early 60s). The main character is washed up on shore and the story ends.