This is a very rough draft. If there’s any clarification necessary or suggestions, please feel free to offer ideas. Sources used for this document include:
Adventurer, Conqueror, King
HackJammer
“Actium: End of the Roman Republic” (Strategy & Tactics #281, Jul-Aug 2013)
Technical notes: HackJammer was used only to derive a formula for the cost of ships, since I couldn’t get ACKS’ galley costs to work nicely for me. The SHP of the small and large galley were used to derive a formula for calculating SHP for larger vessels. The Actium article was used for information on crew size and artillery loadout. The rule for replacing artillery with marines is based on the (large) discrepancies in sources for amount of artillery and number of soldiers carried at various times aboard these types of ships. The number of turns is based on maneuverability ratings from “Actium” and technical reports on the trireme Olympias that reported it could make a 180 degree turn in 1 minute.
Naval combat:
Use a hex map. Each hex is considered to be 30 feet (10 yards) across.
Sustained rowing: Sustained rowing is a steady stroke from the oarsmen that can be sustained for hours if needed. It is just quick enough to ram an enemy if they get close, but since most oared ships have similar sustained speeds, it is difficult to close with an unwilling enemy using sustained rowing.
Burst rowing: Burst rowing is an all-out effort from the oarsmen, and is tiring. A ship can automatically burst row for 2d3 rounds; each round after that, it must make a morale check, with each check after the first at a cumulative -1 penalty. Note that most rowers are considered conscripts (-2 morale). On a result of hostility or resignation, the rowers can no longer maintain burst rowing. The ship immediately drops to Sustained speed and takes a -1 speed penalty for 2d6 rounds. After this time is up, the Sustained speed returns to normal and the ship can Burst speed again.
Example: A octeres wants to close with a trireme. Its captain has a 14 charisma, granting +1 to morale rolls, and the crew are conscripts, inflicting a -2 penalty to morale rolls. The captain rolls 2d3, and the ship can Burst row for 5 rounds. The sixth round, the crew makes a morale check at -1 (+1 for CHA, -2 for conscripts). The captain rolls an 8, modified to 7, and the ship can continue at Burst speed. The seventh round, the crew makes a morale check at -2 (+1 for CHA, -2 conscripts, -1 cumulative penalty). The captain rolls a 3, modified to 1, and the ship immediately drops to its Sustained speed with a -1 hex speed penalty. The captain rolls 2d6, and finds his ship will be slowed for 10 rounds while the rowers recover.
Turns: Each ship has a fractional turn rating. The bireme may make one turn per round. Triremes can only turn every other round, while the largest warships can only make one turn every 6 rounds. Note that ships do not have to move in order to turn, but stationary ships do not normally turn any faster than moving ships. A stationary ship can choose to back one bank of oars. If it does so, it requires one round stationary to prepare. It may then turn at one hexside per round for any number of rounds, then requires one round to prepare to move forward again.
Light Hulls, Standard Hulls, and Armored Hulls: The ship stats presented below are for Standard Hulls. Ships may be built with lighter planking for improved speed or can be sheathed with bronze armor for more protection. A light-hulled ship reduces its AC from 5 to 3, but gains +1 to morale checks for Burst rowing. An armored ship improves its AC from 5 to 6, but has a -1 penalty to morale checks for Burst rowing.
Artillery: Most vessels carry artillery on board. The age of ramming declined when massed fleets became more common, and the large polyremes are less suited for a battle of maneuver than the old biremes. Each ship is presented with the maximum number of artillery weapons that can be placed on its deck. Artillery can be removed for additional sailors or marines. Heavy combat ships use towers to improve the field of fire of their artillery. Ships with towers may carry two ballistas in the towers. Each ballista can fire into either broadside. One can fire to the fore, the other to the aft. All heavy combat ships can carry two weapons (of any type) firing to the fire and two (of any type) firing after. Half of all their non-tower weapons can fire into each broadside.
Biremes and Triremes are Light combat ships, and do not have towers. Biremes can mount one weapon firing forward and one firing aft, with each able to fire into either broadside. Triremes mount two weapons firing one direction and one firing the other (either two fore and one aft or one fore and two aft); the lone weapon can fire into either broadside, while the paired weapons can each fire into one broadside.
Firing arcs: The broadside covers all hexes except those directly in front of or behind the ship. Ships either directly in front of or behind another ship can only be fired on by their fore or aft weapons respectively. Thus, a fore tower ballista can fire into any hex within range except the line of hexes directly behind the ship, while an aft port onager can fire directly behind the ship or into any hex to the left of the ship in an arc that extends to (but does not include) the line of hexes directly in front of the ship.
Marines: Marines are used in close combat or boarding combat. They can be hired per the mercenary table in the ACKs core rulebook. For each artillery weapon removed from a ship, 10 additional marines may be carried. Since the type of marine carried will vary, cost of marines is not included in the crew cost of a ship. Marines are assumed to be responsible for the firing of artillery; if no marines are carried, sailors can fire the artillery, but at a -1 attack penalty.
Monthly crew cost: The monthly crew costs in this document include the cost for a captain and a navigator, and utilize the Mariner costs from page 54 of ACKs. Costs exclude the cost of marines, as their equipment (and thus cost) will vary.
Missile weapon ranges in hexes:
Arbalest – short range 3, medium range 6, long range 12
Bow, Composite or Bow, Long – short range 2, medium range 4, long range 7
Bow, Short – short range 1, medium range 3, long range 5
Crossbow – short range 2, medium range 5, long range 8
Dart – short range 0, medium range 1, long range 2
Javelin – short range 0, medium range 1, long range 2
Sling – short range 1, medium range 3, long range 6
Ballista – short range 5, medium range 10, long range 20
Onager – minimum range 5, short range 10, medium range 20, long range 40
Only the ballista and onager do shp damage. They may be aimed at a ship in general or at a specific target on board the ship. All other weapons must be aimed at a specific target. The onager cannot fire at targets closer than 5 hexes, due to the arc of its projectile.
Crew on deck are considered exposed and may be fired at using their standard AC. Rowers on bottom levels are considered behind a barrier and cannot be shot (although they may be accidentally struck by ballista or onager shots). Top level rowers are considered covered and are attacked as if they were AC 4.
Ballista:
Rate of Fire, Attacks As and Damage are as per ACKs. Range is per the missile weapons information in this file.
Onager:
Rate of Fire, Attacks As and Damage are as per ACKs. Range is per the missile weapons information in this file.
Ship information:
Bireme (Light Warship)
SHP: 100
AC: 5
Sustained speed: 3
Burst speed: 6
Turns: 1/1
Onagers: 1
Ballistae: 1
Rowers: 144
Sailors: 10
Marines: 15
Light ship cost: 9,750 gp
Standard ship cost: 13,000 gp
Armored ship cost: 32,500 gp
Artillery cost: 280 gp
Monthly crew cost: 605 gp
Trireme (Light Warship)
SHP: 120
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/2
Onagers: 2
Ballistae: 1
Rowers: 180
Sailors: 15
Marines: 20
Light ship cost: 12,000 gp
Standard ship cost: 16,000 gp
Armored ship cost: 40,000 gp
Artillery cost: 480 gp
Monthly crew cost: 743 gp
Quadrireme (Heavy Warship)
SHP: 175
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/2
Onagers: 3
Ballistae: 2
Rowers: 220
Sailors: 30
Marines: 30
Light ship cost: 18,000 gp
Standard ship cost: 24,000 gp
Armored ship cost: 60,000 gp
Artillery cost: 760 gp
Monthly crew cost: 953 gp
Quinquereme (Heavy Warship)
SHP: 215
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/2
Onagers: 4
Ballistae: 3
Rowers: 270
Sailors: 30
Marines: 40
Light ship cost: 22,500 gp
Standard ship cost: 30,000 gp
Armored ship cost: 75,000 gp
Artillery cost: 1,040 gp
Monthly crew cost: 1,103 gp
Hexareme (Heavy Warship)
SHP: 250
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/3
Onagers: 5
Ballistae: 4
Rowers: 330
Sailors: 30
Marines: 50
Light ship cost: 27,000 gp
Standard ship cost: 36,000 gp
Armored ship cost: 90,000 gp
Artillery cost: 1,320 gp
Monthly crew cost: 1,283 gp
Septireme (Heavy Warship)
SHP: 285
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/3
Onagers: 6
Ballistae: 5
Rowers: 385
Sailors: 30
Marines: 60
Light ship cost: 31,500 gp
Standard ship cost: 42,000 gp
Armored ship cost: 105,000 gp
Artillery cost: 1,600 gp
Monthly crew cost: 1,448 gp
Octeres (Heavy Warship)
SHP: 315
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/6
Onagers: 8
Ballistae: 6
Rowers: 440
Sailors: 30
Marines: 70
Light ship cost: 36,000 gp
Standard ship cost: 48,000 gp
Armored ship cost: 120,000 gp
Artillery cost: 2,080 gp
Monthly crew cost: 1,613 gp
Enneres (Heavy Warship)
SHP: 345
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/6
Onagers: 10
Ballistae: 8
Rowers: 504
Sailors: 30
Marines: 80
Light ship cost: 40,500 gp
Standard ship cost: 54,000 gp
Armored ship cost: 135,000 gp
Artillery cost: 2,640 gp
Monthly crew cost: 1,805 gp
Deceres (Heavy Warship)
SHP: 370
AC: 5
Sustained speed: 3
Burst speed: 5
Turns: 1/6
Onagers: 12
Ballistae: 10
Rowers: 570
Sailors: 30
Marines: 90
Light ship cost: 45,000 gp
Standard ship cost: 60,000 gp
Armored ship cost: 150,000 gp
Artillery cost: 3,200 gp
Monthly crew cost: 2,003 gp