I recently started a play-by-post game of pirates using the Pathfinder rule set. I didn't like any of the rules available for ship-to-ship combat. The Stormwrack ones were a little too complex and the Pirates CSG rules were too simple. So I melded them together myself. You can check out the rules in my game forum at Online-roleplaying.com - http://online-roleplaying.com/forums...ad.php?t=11324
Edit - Sorry to link off site in my first post. I didn't think copy-paste was a better solution. Maybe it is. In any case, I've been lurking CG for awhile, and while searching for ship deck plans I came across this thread. So, rather than send you off-site (if you're still in the market for the rules), I'll repost part of the rules from my game.
I didn't like any of the systems out there. Arms and Equipment Guide is too complex. The Pirates Constructable Strategy Game is too simple. The Pirates of the Spanish Main is too reliant on the Savage Worlds rules. The Stormwrack rules are the closest to what I finally created, but they were still too complex. So below is what I designed for this game.
Each turn a ship can take two of the below actions, but can only take each action once.
Move - a ship has a base speed listed in its entry. The base speeds are founded on the ship's length. Example--Brigantine has a base speed of 1. That means, barring other factors, the Brigantine can move 1 ship-length on its turn. The ship lengths are for each individual ship. For simplicity's sake, all ship move their full Move per turn.
Turn - a ship has a turn radius listed in degrees. Those degrees are 45, 90, and 135, and each ship will have a different radius depending on its construction and basic ship type. The aforementioned Brigantine has a turn radius of 45 degrees.
Broadsides - each ship can take a broadsides attack with the guns on one side of the ship. The Crimson Widow, which I designed for you, has 12 guns, or 6 per side. So the broadsides action allows for 6 of the guns to be fired at once. Each gun rolls its own attack. More on that later.
Wind speeds provide a multiplier to the base speed of a ship. The wind classes are Light, Moderate, Strong, Heavy, Gale, and Hurricane.
The multipliers are what they sound like. For a Brigantine, with base speed 1, in Light winds it can move 1 ship-length. In Strong winds it can move 3 ship-lengths.
Light Moderate Strong Heavy Gale Hurricane
Multiplier x1 x2 x3 x2 x1 x1 Random
The hurricane multiplier says Random, and that's just what it means. During hurricane force winds, ships have all their sails furled and are at the mercy of the seas and winds. Random will move the ship 1 ship-length in a random direction.
Attacking shipping is based not on ranged attacks and armor classes, but on Profession (sailor) checks against Difficulty Classes for targets. The targets are Rigging, Hull, and Personnel. The DC's are also based on the distance between the ships in battle. Damage is assessed based on the type of guns onboard, with each section having Hit Points. Those are Hit Points are noted in each ship's entry. Once all the Hit Points for a section have been erased, there is a specific effect on the target ship. Dropping Rigging to 0 or below HP makes the ship unable to Move. Dropping Hull to 0 or below HP makes the ship start sinking. It will take 10 rounds for a ship to sink completely beneath the surface of the water (which may or may not change depending on the winds/seas). Dropping Personnel to 0 means the ship loses its ability to Turn. Note that Personnel is an abstract and doesn't denote actual damage to PCs or NPCs.
The DC's may change due to weather, and I'll always note the actual DCs that need to be hit.
Ship-lengths (sl) 1sl 2sl 3sl 4sl
Rigging DC 15 DC 30 DC 45 DC 60
Hull DC 10 DC 20 DC 35 DC 40
Personnel DC 20 DC 30 DC 40 DC 50
Each gun is fired separately by a Player Character or Non-Player Character as you deem it and relies on that character's Profession (sailor) skill.
Guns (cannons are land-based, guns are sea-based) are classified by the weight of the shot they propel and type of shot (Solid, Chain/Bar, Grape). Each gun does damage based on that size as noted below and on the type of shot chosen. Solid Shot is used against Hulls, Chain Shot against Rigging, Grape Shot against Personnel. I am not going to micro-manage the amount or types of shot onboard and the types of shot for each target are set, for simplicity. It is up to the gun captain (the PC or NPC doing the firing) to determine the target, although the ship's Captain may pass on orders to the gun captains to follow.
Note: Guns listed in the ship entry are per side. Double for the full complement of guns onboard.
Solid Chain Grape
4-pounder 1d6 1d4 1d4
6-pounder 2d6 2d4 1d6
8-pounder 3d6 3d4 1d8
12-pounder 4d6 4d4 1d10
24-pounder 5d6 5d4 1d12
32-pounder 6d6 6d4 1d20
The Navigator of a vessel has the ability to affect the actions taken during a round. That effect is determined by a Profession (sailor) check against Difficulty Class for the effect. The Navigator must determine which effect he wishes to use for each turn before rolling and can only use one such effect per round. The effects are Speed Increase, Speed Decrease, and Turn Increase. The base DCs for these effects are listed in each entry, but are subject to modification based on environment or other such factors. I will always post the DCs required.
Speed Increase - Standard DC is 20. By trimming the sails and expertly handling the ship's rudder, the Navigator can increase the ship's speed by 1 ship-length overall. This is not multiplied by the wind. Example - A Brigantine in Light wind can move 1 ship length. With a successful check, the Navigator can increase that speed to 2 ship-lengths. A Brigantine in Strong winds can move 3 ship-lengths. With a successful check, the Navigator can increase that speed to 4 ship-lengths.
Speed Decrease - Standard DC is 25. Usually a ship travels its full Move each turn. By luffing the sails or rocking the rudder back and forth, the Navigator can decrease the ship's speed by 2 ship-lengths to a minimum speed of 0. This is not multiplied by the wind. Example - A Brigantine in Moderate wind can move 2 ship-lengths. With a successful check, the Navigator can decrease that speed to 0 ship-lengths. A Brigantine in Strong winds can move 3 ship-lengths. With a successful check, the Navigator can de crease that speed to 1 ship-lengths.
Increase Turn - Standard DC is 25. While ships can always opt to turn less than their max angle, they cannot usually turn more than it. By maximizing speed and rudder planing, the Navigator can increase the ship's turn angle by 45 degrees. Example - A Brigantine has a turn angle of 45 degrees. With a successful check, the Navigator can increase that turn angle to 90 degrees.