Crews

The crew of a ship determines its Ability scores and enables it to take actions. The total amount of crew, divided into Officers and Able Bodied Seamen (ABS) a ship can support on a voyage is determined by its crew capacity. Crew capacity is determined by the Grade of a ship and may be modified by ship equipment. The crew generally either stays with the boat or in town and will only accompany the PCs on their adventures away from the ship if persuaded.
Officers and ABS alike serve aboard your ship at their pleasure, and you must pay mind to their morale. There are no rules about how you pay or punish your crew, and no written mechanic to keep track of their attitude, but make sure to keep them relatively happy and in line with your orders by dolling out payment, status, and other rewards to dutiful crewmembers, and making an example of mischievous and unruly crewmembers with humiliation, physical punishments, and in extreme circumstances, perhaps even sending them to walk the plank.

Officers

A ship’s attribute’s start at 10, and its modifiers are calculated the same as any PC. These ability scores are increased by the presence of skilled crewmembers called Officers aboard your ship who increase the score of the ship corresponding to their occupation according to the table below by their own modifier in that score. (eg. A navigator with an Intelligence of 15 has an Intelligence modifier of +2, while working on a ship, they increase the Intelligence of the ship by 2). These crewmembers may or may not possess levels in adventurer classes, but they will still possess a level and ability scores. The DM should allow the PCs to decide how their officers develop and enable them to specialize their crew, but keep in mind that the average level of these Officers should be in line with the level of the party.
These Officers are also in charge of specific functions aboard the ship. Having an officer aboard your ship allows them to order ABS to perform the duties assigned to that officer during a turn. As such, every ship should have a captain and a quartermaster to order the ABS in and out of combat. Officer duties are also a flavor consideration, and the DM will delegate these tasks amongst the players and themselves. Be sure you trust these officers, as the characters in control of these positions get the final say for their respective actions if they are confused, possessed, or mutinous.
Only one crewmember at a time may occupy each of these skilled positions. Finding skilled and loyal NPC Officers may be difficult and regardless of their friendship with the party these Officers will likely demand somewhere from a Modest (1gp per day) to a Wealthy Lifestyle (4gp per day) as compensation for working aboard your ship. A player character may fill the role of an Officer and perform their duties aboard the ship, but while they may not require pay, they still count against the total amount of Officers your ship can support as determined by its officer's capacity.

Officer	Related Attribute	Relevant Action(s)	Duties Onboard
First Mate	Strength	Board Enemy Vessel	Commands boardings and rolls initiative.
Cook/Steward	Strength	Set Guard	Protects and keeps track of supplies. Protects the ship while in harbor.
Master Gunner	Dexterity	Fire Weapon	Rolls all ranged weapon attacks.
Hemsman	Dexterity	Raise/Lower Sail, Turn Rudder	Controls ship movement and orders ABS for all movement actions.
Carpenter	Constitution	Make Repairs	Rolls all repair rolls, tracks ship HP.
Boatswain	Constitution	Look Alive, Prepare/Weigh Anchor, Drop/Stow Anchor	Manages anchors, sails, and ropes. Rolls all other Str/Dex/Con checks.
Navigator	Intelligence	Take Readings, Plot A Course	Tracks ship's position and manages direction. Rolls all other Int/Wis/Cha checks.
Quartermaster	Intelligence	Any Action Outside Combat	Controls ABS for any task outside of combat.
Chaplain/Arcanist/Witch	Wisdom	Cast Spell	Casts all spells from the ship's spell focus
Doctor	Wisdom	Heal Wounded	Rolls all crew and PC healing out of combat and handles daily care.
Captain	Charisma	Any Action During Combat	Controls ABS for any action in combat and controls ABS groups during boarding combat.
Musician/Bunting Tosser	Charisma	Signal Vessel	Recruits crew and maintains morale during voyage. Sends and receives inter-ship messages.

Officer NPCs are full characters of a certain level (generally less than that of the PCs) that may or may not posess feats or levels in character classes. Officer NPCs also make death saving throws like a PC, making them slightly harder to kill than the average crewmate.
Changes to the Officers of a ship, or changes to which characters serve as which officers must be done while docked in port or anchored on land.

Able Bodied Seamen (ABS)

In addition to officers, all ships will need to hire unskilled crewmen called Able Bodied Seamen (ABS) to perform the manual labor necessary for a sailing ship to function away from shore. The ABS are often treated as a single uniform entity, and take actions and perform tasks together.
When a ship takes an action on its turn, its officers command the ABS to perform tasks aboard ship. Because ABS are needed to perform nearly every function aboard ship, every grade of ship has a recommended number of ABS for its operation. While the ABS may not serve as essential functions as your officers, they still demand pay, generally somewhere from a Wretched (0p per day) to Modest Lifestyle (1gp per day).
During boarding or on-the-ground combat, the ABS fight as swarms controlled by the Captain. The captain must decide at the beginning of combat how to organize the ABS into swarms of a certain size. the ABS can only form groups of this size, and excess ABS that does not fit into a group must be left out of combat. The properties of the swarm depend on the amount of ABS within it as shown below, and they attack as per the rules of mob combat:
Group of ABS: 10 ABS, Large swarm, individual ABS HPx10
Mob of ABS: 30 ABS, Huge swarm, individual ABS HPx30
Battalion of ABS: 100 ABS, Gargantuan swarm, individual ABS HPx100
ABS are by default, level 0 nobodies living in poverty. Wealthier and more famous sailors can hire more experienced ABS, and after working with you for a while and training under either a PC or your officers your ABS may level up, taking a level in the class of the individual who trained them. The ABS of your ship may only take levels in one class at a time, and extensive re-hiring or retraining will be necessary to change their class. These ABS form more powerful swarms during combat, and those swarms inherit the abilities of their class. ABS max out at level 3, and such elite seamen sail with only the most powerful and prestigious of crews.

Crew Damage, Crew Death, and Wounded Sailors

In the course of combat and adventure, a ship's ABS may be injured or killed. An Able Bodied Seaman who is eaten, vaporized, drowned, decapitated, or otherwise immediately killed by taking damage greater than twice their hitpoint maximum dies immediately.
An Able Bodied Seaman who is broughtto 0 hitpoints but not killed outright becomes a wounded sailor. Wounded sailors are considered effectively "knocked out" for the purposes of acting as ABS. They cannot be spent to perform actions nor can they contribute to tasks or adventures of the PCs. They are unable to do anything besides lay about in the ship, waiting to either recover or succumb to death.
At the end of any combat in which ABS are involved - ship combat or otherwise - You must calculate losses. When you calculate losses, half of the wounded sailors on a ship rounded down die. Wounded sailors remain wounded sailors until the ship makes a Heal Wounded action or the ship returns to safe harbor and the sailors are given leave to seek proper medical care.

Crew Recruitment and Morale