ShipShaper full physics mode replaces standard arcade sailing with an active calculation of buoyancy, hull slenderness, component weight, and center of gravity. When enabled in the sandbox world view, poorly balanced vessels can heel severely in turns, take on water over low deck lines, or capsize under the weight of heavy armament and machinery.
Tomas Sala introduced this simulation toggle during Early Access to give builders a direct way to test the physical seaworthiness of their ships across changing wind, wave, and speed conditions.
How the Full Physics System Works
In standard or unsinkable physics, ships cruise across the ocean without calculating displacement thresholds, meaning top-heavy fantasy builds stay permanently upright. Full physics changes this by evaluating every part placed on the hull, superstructure, and deck.
The simulation evaluates several interlocking mechanical factors:
- Vertical Center of Gravity: Components placed high above the waterline add top-heavy leverage. If the center of gravity rises too far above the waterline, the vessel becomes unstable and capsizes.
- Transverse Weight Distribution: Placing heavy weapons or machinery off-center causes the vessel to list to port or starboard.
- Hull Buoyancy and Draft: Every piece adds real load. As you pile on deck structures, boilers, and guns, the ship sits deeper in the water. If the deck edge or gunports dip below the waterline, water enters and pulls the hull under.
- Hydrodynamic Resistance: Long, slender hull designs cut through the water efficiently to achieve higher speeds. Short, wide, or blunt hulls encounter strict speed ceilings regardless of total engine horsepower.
- Wind and Turning Heel: High winds pushing against full sails cause physical wind heel, while sharp turns at speed force the hull to lean outward.
Unsinkable Physics vs. Full Physics
The physics mode can be toggled directly while testing in the sandbox world view.
| Feature | Unsinkable (Easy) Physics | Full Physics Mode |
|---|---|---|
| Capsizing & Sinking | Disabled; ship remains afloat regardless of design flaws | Enabled; vessel lists, takes on water, or flips if unstable |
| Armament Mass | Guns function as decorative or directional points | Guns act as the heaviest items, requiring wide beams for support |
| Hull Material Mass | Visual styling with minimal performance variance | Wood is lighter and faster; metal with rivets adds significant mass |
| Engine & Propeller Weight | Propellers and paddle wheels grant speed without penalty | Propeller shafts, boilers, and engines add substantial load |
| Keel & Fin Stabilization | Keels act as cosmetic extensions under the hull | Keels actively lower center of gravity and counteract roll |
| Deck Clearance | Waves clip cleanly without flooding compartments | Lowboard hulls and low gunports close or flood if submerged |
Critical Weight Drivers on Your Vessel
Armament constitutes the heaviest category in the game by a wide margin. Large multi-gun batteries, heavy turrets, and armored siege cannons concentrate mass into single points on the deck. Stacking four triple batteries onto a narrow frigate hull will cause immediate capsizing unless the ship possesses a wide beam and adequate counterbalance below the waterline.
Propulsion hardware also increases displacement load. Boilers, haystacks, funnels, smokestacks, and engine blocks add tonnage beneath the decks. Propellers carry shaft weight that drags the stern lower, which can cause excessive aft trim if you place multiple screws on small craft.
Hull materials further determine initial buoyancy. Selecting a metal hull with rivets yields high hull integrity but significantly increases dry weight compared to standard wooden planking.
Stabilizing Your Ship Against Sinking
To keep large warships and complex builds afloat under full physics, use counterweights and hydrodynamic stabilizers located in the Keel Items category and hull menus.
- Install Ballast Keels: Placed along the centerline under the hull, ballast keels concentrate heavy mass at the lowest physical point. While they make the ship sit deeper in the water, they significantly lower the center of gravity, allowing taller superstructures and top decks to remain upright.
- Mount Keel Fins or Twin Keels: Keel fins steady the hull against lateral rolling without adding excessive downward mass. Twin keels provide double the stabilization surface and can be stretched or angled outward.
- Attach Leeboards or Diving Rudders: Leeboards mounted along the sides dampen roll forces from strong crosswinds and sharp turns. Diving rudders stabilize roll while enabling underwater diving controls in world mode.
- Widen the Hull Beam: If heavy broadside guns cause severe listing, pull the hull nodes outward to create a wider, more buoyant platform that resists tipping.
- Adjust Sail Rigging for Weather: High winds on full sails will push an unstable ship onto its side. Lowering canvas to fighting sails or storm sails reduces heeling leverage during rough sea states.
- Equip Salvage Cranes on Fleet Vessels: In squadron play, if a ship sinks during sea trials, an accompanying ship equipped with a giant salvage crane can sail to the wreck site to haul the sunken hull back to the surface.
Frequently Asked Questions
Why does my ship instantly sink when entering world mode?
Your vessel is either overloaded beyond its hull displacement or top-heavy. Heavy turrets, broadside guns, and engine parts placed high on the decks can invert the center of gravity, causing the hull to immediately roll over and take on water.
How do I turn full physics off if my design will not float?
Click the physics toggle button on the world mode interface to switch back to unsinkable physics. This stabilizes the vessel instantly, allowing you to test sailing behavior and squadron maneuvers without capsize risks.
Does hull material change how fast a ship sails in full physics?
Yes. Official game updates confirm that wooden hulls are lighter and reach top speeds more readily, whereas metal hulls with rivets are heavier, lower the waterline, and require stronger sail or engine power to move.
Can sunken ships be recovered without resetting?
Yes. If you operate in squadron mode with a ship outfitted with a controllable salvage crane, you can sail up to the sunken wreck, lower the crane hook, latch onto the attachment point, and tow the hull to the surface.
