Movement Under Sail (5e Variant Rule)

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Ship Movement on a hex grid, Credit: Jon Grover, 2020, public domain

Movement Under Sail[edit]

This is a good rule to use if you have lots of maritime adventures. It adds more realism, challenge, and complexity, which may be fun if you have many adventures at sea.

Basic Rule
- Ship speed is the minimum of the values found on the two tables below.


  • Ship Speed To determine ship speed, look a the situation of the ship on each table, and choose the lower number of the two numbers.
  • Wind Determination Roll 1d6 for wind direction on a hex map and 1d6 for wind speed (table 1) at the beginning of an encounter.
  • Direction Change Changing a ship's direction requires an action by the helmsman and some of the crew. If the ship is large enough, the direction change requires a series of actions over multiple turns. Ship direction changes are based on ship size. For example a 60 ft. ship takes 2 turns to change its direction by 1 hex whereas a 15 ft boat can change to any direction in one turn.
  • In Irons If the helmsman does not wait an entire minute after making a direction change, and the ship ends one of its turns 'against the wind', then the ship stalls and finds itself 'in irons', facing directly into the wind. Generally a boat or ship has enough momentum during a direction change to carry it through one full direction change which includes a facing into the wind but not two direction changes where a turn of the change ends against the wind. If the helmsman waits a full minute after a direction change before changing direction again, then the ship is considered 'under weigh', and the helmsman can change the direction of the ship without being 'in irons'.
  • Recovering from Irons The helmsman must wait a full minute for the wind to push the ship backwards (see 'against the wind' speeds below) in order for the ship to be 'under weigh' again, and allow the helmsman to make a direction change.

Table 1: Maximum speed based on wind, wind speed, and boat direction+:

d8 Wind Speed Wind Speed Beam Reach Reaching Running Beating Against the Wind Wind Term
1 0 knots 0 ft. 0 ft. 0 ft. 0 ft. 0 ft. 0 ft. Calm
2 3 knots 30 ft. 30 ft. 30 ft. 25 ft. 10 ft. -5 ft. Light Air
3 6 knots 60 ft. 60 ft. 60 ft. 50 ft. 20 ft. -10 ft. Light Breeze
4 9 knots 90 ft. 90 ft. 90 ft. 75 ft. 30 ft. -15 ft. Gentle Breeze
5 12 knots 120 ft. 120 ft. 115 ft. 100 ft. 40 ft. -20 ft. Moderate breeze
6 15 knots 150 ft. 150 ft. 140 ft. 125 ft. 50 ft. -25 ft. Moderate breeze
7 18 Knots 180 ft. 180 ft. 165 ft. 150 ft. 60 ft. -30 ft. Fresh breeze
8 21+ Knots 210+ ft. 180 ft. 165 ft. 150 ft. 60 ft. -30 ft. Stronger Wind

+ Except for wind speed 'knots', all measures are in units of ft. per turn.

Table 2: Maximum speed based on hull length at the waterline and hull type:+

d8 Waterline length Racing Ship Pirate Ship Cargo Ship Barge Raft Direction Change Speed
1 15 ft. 50 ft. 40 ft. 30 ft. 20 ft. 10 ft. 3 hexes/turn
2 30 ft. 70 ft. 55 ft. 45 ft. 30 ft. 15 ft. 2 hexes/turn
3 45 ft. 90 ft. 70 ft. 60 ft. 40 ft. 20 ft. 1 hex/turn
4 60 ft. 100 ft. 90 ft. 80 ft. 50 ft. 25 ft. 1 hex takes 2 turns
5 90 ft. 120 ft. 100 ft. 90 ft. 60 ft. 30 ft. 1 hex takes 3 turns
6 120 ft. 140 ft. 120 ft. 100 ft. 60 ft. 30 ft. 1 hex takes 4 turns
7 150 ft. 160 ft. 130 ft. 110 ft. 60 ft. 30 ft. 1 hex takes 5 turns
8 180+ ft. 180 ft. 140 ft. 120 ft. 60 ft. 30 ft. 1 hex takes 6 turns

+ Except for waterline length, all ft. measures are in units of ft. per turn.


Beam Reach
means traveling perpendicular (90 degrees) to the wind. A beam reach is the most efficient.
means traveling 60 degrees from the wind (somewhat with the wind), also 120 degrees from the wind for a small boat.
means traveling in the same direction as the wind, or up to 30 degrees from the wind.
means traveling 120 degrees from the wind for a large ship (somewhat against the wind), or 150 degrees from the wind (strongly against the wind) for a small boat.
Against the Wind
means pointing your ship directly into the wind, or 150 degrees from the wind for a large ship. The negative numbers indicate how fast the ship is driven backwards by the wind.
Wind Term
Ships are optimized for, and sail best in a fresh breeze, and do not gain additional speed with stronger wind. Gales range from 270 ft. to 540 ft. and crews need to take special steps to sail safely in gales. Hurricanes begin at 660 ft. and can have winds up to and beyond 1200 ft. Ships are in significant danger in hurricanes.
Waterline Length
The full length of a ship including upper deck and spars can be anywhere from 25% longer to 50% longer than the waterline length.
Racing Ship
This indicates the fastest possible sailing ship without magic. Pirate ships will be somewhere between this optimum and the cargo ship below.
Pirate Ship
A narrow ship designed for speed and for overtaking cargo ships. Contains about half the cargo space as a cargo ship.
Cargo Ship
Standard ships that are usually the ones encountered in a campaign.
A slow ship intended to carry large amounts of cargo in relatively sheltered waters. A 'hulk' is a kind of barge.
An ad hoc ship built temporarily. Large rafts are sometimes built out of logs as a means of transporting logs. Except for 15 ft rafts, rafts are not seaworthy.
Direction Change Speed
Small boats can change direction very quickly, large ships take a long time.

Distance Traveled Per Day[edit]

A ship can travel 24 hours per day if it has an adequate crew to take shifts and there is a steady wind. To determine how far a ship can travel during a day, first figure out its speed per turn using the tables above. Then multiply the speed per turn by 2.5 to determine the number of miles the ship will travel in a day. For example if the tables above indicate the ship can travel at 80 ft. per turn, the distance per day would be 200 miles.

  • Cut distance per day in half if the crew is smaller than the crews indicated below. She ship will have to set a sea anchor during the night if there are not enough crew to operate the ship both night and day.
  • If the wind is not steady and changes direction frequently or dies down at times, cut the distance by a third.

Table 3: Other details related to ship size, normalized to a 'cargo' ship:

d12 Waterline length Width Crew Size Capacity Navigable River Cost Historical Examples
1 15 ft. 5 ft. 2 3 medium creatures 30 ft. or more 120 GP Skiff (Ancient, triangular sails)
2 30 ft. 10 ft. 3 or more 6 medium creatures 100 ft. or more 1000 GP 5th century currach (Welsh, square sails)
3 45 ft. 15 ft. 4 or more 15 medium creatures 250 ft. or more 4000 GP 8th century knarr (Viking, square sails)
4 60 ft. 20 ft. 6 or more 30 medium creatures 400 ft. or more 9000 GP 9th century long ship (Viking, square sails), 15th century caravel (Portuguese, triangular sails)
5 75 ft. 25 ft. 8 or more 55 medium creatures 500 ft. or more 17,500 GP 12th century cog (Hanse, square sails), 14th century hulk (Dutch, square sails)
6 90 ft. 30 ft. 10 or more 100 medium creatures 600 ft. or more 30,000 GP 16th century galleon (Spanish, triangular sails)
7 120 ft. 40 ft. 12 or more 200 medium creatures 700 ft. or more 70,000 GP 17th century ship of the line (Dutch, English, French, Spanish & Swedish, square sails)
8 150 ft. 50 ft. 15 or more 400 medium creatures 800 ft. or more 150,000 GP early 18th century ship of the line (also British, Italian, Russian, Ottoman, square sails)
9 180 ft. 60 ft. 20 or more 800 medium creatures 900 ft. or more 250,000 GP late 18th century ship of the line (also American, square sails)
10 210 ft. 70 ft. 30 or more 1200 medium creatures 1000 ft. or more 400,000 GP early 19th century ship of the line (also Egyptian, square sails)
11 240 ft. 80 ft. 40 or more 1700 medium creatures 1100 ft. or more 600,000 GP mid 19th century ship of the line (square sails)
12 270 ft. 90 ft. 50 or more 2400 medium creatures 1200 ft. or more 900,000 GP In 1855, The Bretagne, 266 ft at the waterline (French, square sails)

The largest functional wooden sailing ship ever built was the Bretagne in 1855. It was 266 ft at the waterline. Beyond that size, wood begins to be insufficient for a ship to have good cohesive integrity. A larger wooden ship flexes and leaks. The Bretagne could carry 1800 passengers. As a warship it had a complement of 1170 crew and soldiers, and 180 guns.

This is the width of the deck (and the ship) for a 'cargo' ship. Cut this by 1/3 for a pirate ship. Cut this by 2/3 for a racing ship. Minimum 5 ft.
Deck Length
Deck length will be 20% more than waterline length. Spars will add another 20% to length.
Crew Size
This is generally the size of crew needed to operate the ship 24 hours per day with watches. This number does not include soldiers to fight off pirates or monsters and does not include passengers. Crew cost should be about 4d6 SP per day per crew member for wages, or 4d10 SP per day if you include food costs etc.
This is reasonable number of medium creatures the ship can carry for a 1 month voyage including food and water. For all small creatures, add 25%.
Navigable River
A river must be at least this wide or wider for a ship of this size to maneuver without being towed. Also the river current must not move faster than the boat.

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