BoneEngine

BoneEngine

Ever been stuck at a beach rowing backward, or in a headwind? Drop bone fragments in your boat's storage and the

boat gets an engine that runs on bones. Supports both forward and reverse. Client-side and vanilla content only.

How to Use

• Put bone fragments in the boat's storage (Karve, Longship, Drakkar). The Raft has none.
• Sail. The engine's power follows the sail setting, and reverse always runs in low: rowing low, half sail in the

middle, full sail at full. The push works the same in any wind.

• The count shows under the wind compass while you steer, and on the rudder text when you walk up to it.

How Things Behave

• The engine takes one bone at a time. The count is what's left to burn: an active engine at 0 is on its last bone.
• A stopped boat consumes none.
• The amount of bones only determines how long the engine runs. The push is fixed, scaled by the sail setting only.
• The boat's speed reverts to vanilla if the bones run out. Add more and the engine picks up.

Sailing Stats

Top speed at full sail (m/s)

| Boat | Tail/side wind (vanilla) | Tail/side wind (engine) | Headwind (vanilla) | Headwind (engine) |

|---|---|---|---|---|

| Karve | 4.6 | 7.5 | 2.0 | 6.0 |

| Longship | 5.9 | 9.7 | 2.0 | 7.7 |

| Drakkar | 5.5 | 9.0 | 1.6 | 7.1 |

The sail doesn't do anything in a headwind on vanilla boats, so they fall back to rowing speed. With bones, keep

full sail up anyway: the engine runs at full power despite the wind.

How long each bone lasts (in seconds)

Heavier boat uses more fuel.

| Boat | Full sail | Half sail | Rowing or reverse |

|---|---|---|---|

| Karve | 25 | 37.5 | 75 |

| Longship | 15 | 22.5 | 45 |

| Drakkar | 9 | 13 | 26 |

Time per kilometer

| Boat | Tail/side (vanilla) | Tail/side (engine) | Headwind (vanilla) | Headwind (engine) |

|---|---|---|---|---|

| Karve | 3:38 | 2:13 (6 bones) | 8:20 rowing | 2:47 (7 bones) |

| Longship | 2:49 | 1:43 (7 bones) | 8:20 rowing | 2:09 (9 bones) |

| Drakkar | 3:03 | 1:51 (13 bones) | 10:25 rowing | 2:20 (16 bones) |

On the world scale

Longship at full sail with tail/side wind.

| Trip | Distance | Share of the world | Vanilla | With engine |

|---|---|---|---|---|

| Island to island | 1 km | a twentieth | 2:49 | 1:43 |

| Spawn to the far biomes (Ashlands, Deep North) | 9 km | just under half | 25:25 | 15:28 |

| One edge of the world to the other | 20 km | the whole way | 56:30 | 34:22 |

These are straight-line distances. Real trips bend around coasts and weather, so expect longer.

Engine Power

Water holds a boat back in proportion to the square of its speed. In the real world that is the drag equation:

drag = 0.5 × water density × drag coefficient × frontal area × speed to the power of 2

Valheim folds everything except the speed into one drag constant per boat:

drag = drag constant × speed to the power of 2

A boat stops speeding up when its push equals the drag, which puts its top speed at:

top speed = square root of (push / drag constant)

That is why doubling the push gives about 1.4× the speed, not 2×. The engine pushes about 1.7 times as hard as a

full sail in a tail or side wind, on top of whatever the sail gives. With the wind behind or beside you that comes to about 1.6×

the vanilla top speed. In a headwind the engine is the whole push.

The engine's power is fixed on purpose, for two reasons:

• Immersion. The world should still feel big. The far biomes remain a quarter-hour voyage, not a quick hop.
• Performance. The game builds the land ahead of you in 64 m squares, and a faster boat makes it build them more

often. Near busy coasts like the Black Forest, that shows up as stutter on lower-end PCs.

Multiplayer

Everyone sees the faster boat. Nothing to install on the server. The engine runs in the steerer's game, so the one

at the rudder needs the mod. A friend without it steers at vanilla speed and burns nothing. Changing hands, by

taking the rudder or opening the storage, costs at most the bone being burned. A friend opening the storag