I didn't get any response to the naval post on Tuesday; but perhaps this will poke the bear into growling:
Each ship of a certain size has the capacity to be fitted with either ballistae or catapults, which can be used directly against enemy hulls, rigging, siege engines or crew. These are fitted along the left or right hand sides of the ship (port or starboard), enabling fire to be directed outward. For the purpose of our game, an engine cannot be mounted so that it fires directly forward or backward from a ship - because it wasn't done consistently. I haven't been able to find the reason for this, except perhaps that the up and down movement of the stern and bow make such a mount impractical.
Siege engines aboard a ship are supported by ordinary missile weapons, standard to D&D (bows, crossbows, slings, etcetera). Rules that relate to the use of siege engines and these weapons aboard ship are described below.
The amount of weaponry that can be placed aboard ship is not limited only by the amount of weight or deck space that a ship possesses. Much of a ship's deck space is required for the movement of the crew and the management of the ship. Thus, the number of weapons is limited by the number of hardpoints that a ship has. A hardpoint is a location aboard the ship in which a ballista or catapult can be placed. Ships will always have an even number of hardpoints, distributed equally to both sides of the ship. There will be two hardpoints (one on each side) for every three points of hull defensive points a ship possesses (see Ships). For example, a caravel has 3 hardpoints on each side of the ship, while a carrack has 4. A frigate has 5. A yawl has only 1.
There are four siege engines that can be mounted aboard ships: the large ballista, the small ballista, the light catapult and the heavy catapult. Large ballista and heavy catapults each require two hardpoints to mount aboard ship. A small ballista or a light catapult requires only one hardpoint. When two hardpoints are wanted for mounting a heavier weapon, they must both be on the same side of the ship.
Therefore, a frigate with 5 hardpoints on each side of the ship (10 altogether) could mount 4 heavy catapults, two on each side, and 2 light catapults. A frigate could not mount 5 heavy catapults, as the two remaining hardpoints are on opposite sides of the ship.
The following table gives the basic statistics for missile weapons that can be employed during ship-to-ship combat, with ranges adjusted to the width of naval hexes (for missile ranges in direct hand-to-hand combat, see All Weapons).
As with standard combat, the effect of medium and long range on weapons is the same: all weapons that attack at medium range are -2 to hit; those attacking at long range are -5 to hit. In all cases, the chance of a ballista, catapult or any other weapon to hit a standard combat target (creature) is a d20 against that creature's armor class. In all cases of a missile weapon fired directly at an enemy ship, the ship should be considered AC 5. Note that catapults cannot fire at targets that are close up - and that all catapult attacks are done at either medium or long range.
The rounds to load for a ballista or catapult describes the time necessary for a crew of that number. It is possible for a smaller crew to load these weapons. Note, however, that only the small ballista can be loaded by 1 crew; all other weapons must have at least 2 crew or else the tension cannot be created that will enable the engine to fire. Load times for less crew can be worked out as a ratio. In all cases, round fractions up and always add 1 more to the total as a trouble factor:
- 2 persons loading a heavy catapult will take four times as long as 8 persons, +1 trouble factor = 13 rounds.
- 7 persons loading a heavy catapult would require 3.429 rounds; this translates to 4, +1 trouble factor = 5 rounds.
- 1 person loads a small ballista, taking twice as long, +1 trouble factor = 3 rounds.
The time that takes to load counts as the time between firing; once an engine (or any weapon) is fully loaded, the firing of that weapon takes place on the next round - NOT the round in which the weapon's loading was completed. A bow, therefore, loads 1 round, then fires the next; it loads again in the 3rd round, fires in the 4th and so on.
Note that multiple attacks for high level fighters do not apply to loading siege weapons, unless all members of the crew are able to move as quickly; the same is true if one member of a crew is hasted or has imbibed a speed potion; if others must be waited for, than the overall loading of the siege engine is not improved.
Damage to Creatures
The table above gives three forms of damage: hits (direct hits), skipping and shrapnel. Direct hits cause the most damage.
Catapult balls made of solid stone will 'skip,' even after hitting an opponent, potentially causing damage to creatures. See rules for Skipping.
Catapult balls that are constructed of broken stone and low-grade masonry will shatter when hitting a hard object; ballista bolts will also break apart when hitting a hard object. These will both cause damage to creatures even when a miss has occurred. See rules for Shrapnel.
Engines vs. Ships
Only siege engines may be used to directly attack ships. Note that the artillerist must announce before firing that they are aiming at the enemy ship and not its crew. I have decided not to allow pin-pointing a specific target on the enemy ship - although I know this makes no sense, given that a specific creature on an enemy ship CAN be targeted. After trying and discarding a few tables that would allow targeting, I've come to the conclusion that, on the whole, it would not improve the overall experience of ship-to-ship combat, while it does greatly increase complexity. Therefore, all damage will be relatively random. Note, however, that many of the results below can mean damaging multiple parts of enemy's ship: and in any case, it must also be noted that a direct hit against a large, tremendously massive vessel could quite reasonably have no effect whatsoever (bouncing off a particularly supported surface or passing right through rigging without any effect).
Therefore, the player should suppose that expertise, not player desire, is the determining factor in what part of the ship is aimed at: and that if a hit occurs that causes damage, that is what the character (if not the player) meant to aim at.
Once it has been resolved that the enemy's ship has been hit (a successful hit against AC 5), the artillerist will use the Damage Gauge table below to determine the effectiveness of the siege weapon:
As indicated, the artillerist adds the range modifier to the artillerist's number to hit AC zero to determine the effectiveness of the range weapon against the enemy's ship.
For example, suppose that Albert, the lead artillerist with a light catapult's crew is a 8th level fighter, giving him a THACO of 13. He therefore adds +1 to the "gauge" of damage he can cause. If he did not have an artillerist's skill, he would -1 from that gauge, but let's say he does not. This means that when his crew hits a ship at medium range, the shot's gauge is +1+1, or 2; against a ship at long range, the gauge is 1.
This is then compared with the table below:
Against a medium range ship, Albert rolls 2d6 on the '2' column; his chance of causing damage to the ship's hull, rigging, crew or siege engines is high, 5 in 6. At long range, Albert rolls on the '1' column, reducing his chance of causing damage to 15 in 36.
NOTE, a result of no damage does not indicate that the ship has not been hit. It has to be understood that these vessels are powerfully built and are able to be struck with weapons like ballista bolts and catapult balls without any appreciable effect. It takes a very excellent artillerist, working with the best weapons at the ideal range to cause considerable damage to enemy shipping. Most artillery crews will not be led by extraordinarily high level commanders and artillerists, greatly increasing the chance that the weapons they are using will often be ineffectual.
Whew. I'm done for now. I'll be working on details regarding the effect of hits against hulls, rigging, engines and crew at some point this week: not tomorrow, I hope. The page on the wiki for the above content can be found as "Ship's Weaponry."
None of this has been play-tested - though it is based on the Wooden Ships and Iron Men system, reworked for D&D. It ought to work; eventually, when I am running games again, I'll give it a shot and see how it plays out.