Love and Pennies - Erotica by Dena Hankins, #2

Intrepid sailors caught in a terrible storm are forced to go below decks and keep themselves busy somehow. With the heaving of the sea, a simple kiss between these long term lovers heats the cabin past bearing. The only trouble is that she's on her period and keeping her cup in place is the best idea. When he decides he wants to taste her regardless, she finds out what it's like to let the ocean really provide the motion.