Having just read Robert Louis Stephenson's Treasure Island for the first time, I was wondering why you don't see more Pirate-themed pen&pencil RPGs. I think there are a number of reasons:
- Scale- managing a ship with a full crew is a bit larger-scale than your typical RPG is comfortable with
- Naval Battle Rules- need custom rules for naval battles- both from a distance and for boarding your opponents' ship
- DnD firearms- the most popular RPG system doesn't really have satisfying firearms rules
- Have a model/drawing of the ship and it's crew ready for combat
- Have a simple list of stats for each ship
- Limit the technology level: small ships are easier to manage
- Come up with simple rules for naval combat. Something along the lines of Evil Stevie's Pirate Game which tracks rigging damage, hull damage, and crew member survival. I'm not sure if I'd keep the rules for wind direction, etc. Maybe that could be abstracted as "Captain skill+Ship Maneuverability+ Ship Size" i.e. what chance you have of getting off a shot on a given round while avoiding your opponents' shots.
- Adopt personal combat rules from a firearm-friendly system like CP2020 or WFRP
I don't think I would like to start the players as low-ranking crew-members on a pirate ship since they are then not the ones making the decisions. Instead I prefer something along the lines of:
- The pirate captain has just died and one of you has been elected the new captain
- You are on a military ship and have just mutinied. The remaining crew have decided to go pirate
- You are vagabond seamen who saw the opportunity to steal your own ship and you have done so. Now you are on the run from the law
Players must agree who will be the officers, mainly Captain and First Mate. Each of these has skills associated with them like leadership, pilot ship, navigation and players can choose other relevant skills like: gunnery, carpentry, melee combat.
To fill out the crew, add a minimal number of NPC crew-members that are also divided among the players.
The setting should be fairly unruly, like among colonies of a far-spread empire. The players have a map of a major port or two they are familiar with, but most of the map is uncharted, providing lots of opportunity for exploration.
Of course, for a sandbox we would need random tables galore. Particularly:
- Random ship(s) & crew(merchants, military, pirate?)
- Random uncharted island(inhabitants?)
- Random adventure hooks(treasure map, gold shipment, Governor or other official to be kidnapped/ransomed...)