Floating, speed and turning

Every sealed part pushes water aside and is held up by it. A ship floats while that lift is greater than its weight. The spare lift is its flotation reserve: the more you have, the higher the ship rides and the more damage it survives.

Plain hull is light and gives the most reserve for its price. Armor protects what is behind it but weighs far more for the same space:

One full block of each structural material

Full block	Mass	Integrity	Armor rating	Price
Deck	15 t	5 MJ	None	2 Coins
Hull	15 t	20 MJ	None	2 Coins
Light armor	49.5 t	22.5 MJ	130 MJ	80 Coins
Medium armor	126 t	108 MJ	520 MJ	160 Coins
Heavy armor	257 t	324 MJ	1,170 MJ	480 Coins

Heavy armor everywhere sinks a hull. Armor the parts you cannot afford to lose and build the rest from plain hull. What each grade stops is in Armor and damage.

Weight high above the waterline tips a ship over; weight low in the hull steadies it. Guns, armor and superstructure count where you put them. Engines and funnels are the exception: their weight is counted 25% of the way up the hull beneath them, where a real ship carries its boilers.

A ship that rolls past 75° has capsized and takes on water. If a design lists or turns over in a Test, move heavy parts lower and closer to the centre line, widen the hull, or add ballast low down.

Speed comes from engine power against weight and drag. Armor weight slows a ship through the same sums as any other weight; there is no separate penalty. A propeller only pushes while it is under water, so a light ship that rides high can lose thrust. Engines compares power, mass and price.

Long ships turn wide. At full rudder a hull settles on a circle whose radius grows with the square of its length, so a hull twice as long needs four times the room. The starter's rudder area for its length gives a radius of length² ÷ 420 m.

More rudder area in the water tightens the turn, with diminishing returns: no amount does better than half that radius, and no hull turns tighter than 0.5 of its own length. Less rudder widens it, and with no working rudder in the water the ship does not turn at all. A fast ship turns wider than a slow one.