With regards to ship combat, it is less desirable to board and engage with the enemy than many might suppose. Boarding a vessel can be a costly method of capturing an enemy ship, because crew losses - even on the winning side - may greatly reduce the further fighting potential of both ships. More than the loss of men, there is the loss of competency to be considered, when sailors of quality are killed in random attacks by ordinary thugs who are useless at sailing the vessel. For this reason, most rigged ships will find that boarding is practical only after firing has reduced the size of the enemy crew.
It is recommended that readers unfamiliar with these rules should begin by familiarizing themselves with ships and ship's weaponry, before reading into boarding and melee as it is usually played out in D&D. Note that the system that is included here is designed to be run without any changes to the D&D combat system as described on this wiki: the ship combat rules here are not a separate system. When members of a crew board an enemy vessel, that combat is played out round by round - as is the movement of all the ships in the game, without any change to the length of a given combat round.
See these links associated with naval combat and warfare:
Line of Sight
Movement in Naval Combat
Wind & Sailing