I'm having some troubles figuring out how to calculate ships CMB and CMD. Mainly, do you add the captains sailing skill to a ships CMD?
Adding it to the attackers CMB seems straightforward and supported by the rules:
Grappling:
If only one pilot wants to grapple, she must make a combat maneuver check against the target ship’s CMD, using the base CMB of the ship plus the pilot’s sailing skill modifier (or Wisdom skill modifier if she is using that ability to control the ship) as the total CMB of the grappling maneuver.
Ramming:
The ship’s pilot must make a ramming combat maneuver check against the target’s CMD, using the base CMB of the ship plus the pilot’s sailing skill modifier (or Wisdom skill modifier if she is using that ability to control the ship) as the total CMB of the ramming
maneuver.
Furthermore, under the heading ships statictics, it says:
CMB and CMD: The ship’s base CMB and CMD. To calculate the ship’s actual CMB and CMD, add the current pilot’s sailing skill modifier (or Wisdom modifier, if she is using that ability to drive the ship) to the ship’s base CMB.
Nowhere is it stated that you add sailing to the CMD of a ship. However, all ship stats presented in Raiders of the Fever Sea have added the captains sailing to the CMD. This makes ramming extremely unlikely to have any real effect (since it sets your own speed to 0, but only affects opponents speed if you beat his CMD by 10).
So, is the players guide or Raiders' shipblocks wrong?
It's a typo. You add the sail check to both scores. Its worded slightly badly I think that's all. I hope.. otherwise me and the guys writing the ship stats in every book in the series have been doing it wrong
That leaves ramming as a very weak tactic.
Most ships have CMD = CMB+10.
Assuming captains of equal skill, you need to roll 10 to succeed on a ramming attempt... however, just hitting that number sets your speed to 0, whereas the opponent keeps his speed as it is. On his next round, he'll accelerate or just sail away, moving 120-180 feet away. You, on the other hand, has to accelerate to 30', and then do a double move.
So if you merely hit, you've dealt 8d8 damage (not a lot against a ship with 1000+ hp), but given your foe a golden opportunity to get away.
In order for ramming to make any sense, tacticly, you need to beat his CMD by 10, meaning you have to roll a 20 (assuming captains of equal skill). Anything less than that, and you've basicly lost all chances of gaining on the other guy.
That's one of the reasons I don't like the ship rules in the players guide. I'm going to try out the rules from Fire as she Bears next time I run in a week or 2, they seem a lot better.
Ram in that book has no CMB check and does a ton more damage too. If you are having issues with the rules it might be a good idea. Its a REALLY good book trust me.