Being dissatisfied with D&D's ship mechanics (or lack thereof) from the Player's Handbook and Ghosts of Saltmarsh, I decided to make my own system in that works seamlessly with the normal flow of a D&D game. The PDF fleshes out the six stat blocks already given by D&D for each ship, and gives them more purpose in turn-based naval combat. In this system, individual characters can move and have purpose during naval combat without every single character and NPC aboard the vessel getting a turn and bogging down gameplay. I hope this is a helpful addition to D&D, as I have not seen another sufficient system dealing with naval combat.
Samuel's Library