> For the complete documentation index, see [llms.txt](https://create-deep-seas.gitbook.io/create-deep-seas-wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://create-deep-seas.gitbook.io/create-deep-seas-wiki/high-seas/mechanics/sails-and-halyards.md).

# Sails and halyards

## How a ship sails

Build sails out of [Ship Sail](/create-deep-seas-wiki/high-seas/ship-sail.md) blocks. Sail blocks that touch each other in the same plane form one sail, and the bigger it is, the more wind it catches.

On a ship that floats, sails always push the ship **toward its bow**. The bow is the end away from the [Rudder](/create-deep-seas-wiki/high-seas/rudder.md). The wind only decides how hard they push, never the direction: the keel takes the sideways push, like a real boat. Without a Rudder, the ship sails along its longest side, toward the side the sails face.

{% hint style="info" %}
Sails only work in the air. A sail under the water catches nothing.
{% endhint %}

## Square sails and triangle sails

How hard a sail pushes depends on the angle between the wind and the ship's course, and on how the sail is set.

* **Square sails** stand across the deck. They are best with the wind behind you.
* **Triangle sails** (jibs, lateen sails) stand along the deck, from bow to stern. They are best with the wind from the side and can sail up to about 40 degrees from the wind.

| Wind              | Square sail | Triangle sail |
| ----------------- | ----------- | ------------- |
| Straight behind   | 100%        | 60%           |
| 45 degrees behind | 80%         | 90%           |
| From the side     | 30%         | 100%          |
| 45 degrees ahead  | nothing     | 60%           |
| Straight ahead    | nothing     | nothing       |

A sail set at an angle mixes the two. A ship facing a wind none of its sails can use still keeps 10% of its speed (`sailUpwindEfficiency`), so you are never completely stuck. Mixing both kinds of sails lets you sail on almost any course.

A ship notices a sail being added or removed within a second (`sailRescanInterval`, in ticks; higher is cheaper on the server but slower to notice).

To make a clean triangle, build the edge of the sail as a staircase. Every step cuts itself diagonally and the sail becomes a triangle with a straight edge.

## Speed

A fully rigged ship running before the wind cruises at 4 times the square root of its length, in metres per second (`sailHullSpeed`). So:

* a 4 block raft does about 8 m/s,
* a 13 block ship reaches the cap of 14 m/s (`sailMaxSpeed`). Nothing goes faster under sail.

Longer ships are faster, but they also need more canvas. If a ship has too little sail for its weight, it only reaches part of its top speed. A heavier ship needs more sail (`sailCanvasNeeded`).

A stronger wind helps too: the speed goes from half in a light breeze up to 130% in a storm.

Ships do not reach their speed at once. A small ship takes about 5 seconds to pick up speed (`sailResponseTime`), a big one up to twice as long.

## Airships

Sails work on flying ships too. In the air there is no keel, so the ship is pushed the way the wind blows, harder the more squarely the sail faces it. Combined with the extra wind at altitude, a sail on an airship is a real engine.

## Masts on bearings

A sail on a mast mounted on a bearing still pushes the whole ship, not just the mast. You can turn the mast to trim the sails to the wind.

## Halyards: reefing a sail

A halyard lets you lower and raise a sail from a Rope Winch.

1. With a Rope or a [Steel Cable](/create-deep-seas-wiki/deep-seas/cables-and-tools/steel-cable.md) in hand, right-click any block of the sail.
2. Right-click a Rope Winch on the ship. You can also do it the other way round, winch first.
3. The line finds the edge by itself: the tall edge on a triangle sail (the mast side), or the edge closest to the winch on a square sail. It is tied at the top of that edge and runs down to the winch.

Reel the winch in: the head of the sail slides down the edge and the sail pushes less and less. Let it out and the sail climbs back up. Past 90% lowered, the sail stops catching anything and you can walk through it.

* You can add or remove sail blocks while it is rigged, the halyard follows within a second.
* The line never goes slack: letting the winch out further than the sail is tall does nothing more.
* Rig both edges of a sail, each to its own winch, and they work together: turn either winch and the other line follows.

Use it to slow down in a storm, or to stop without dropping the [Anchor](/create-deep-seas-wiki/high-seas/anchor.md).

## Colours

Use a dye on a sail to change its colour. Keep using the dye on it to spread the colour across the whole canvas.