Coating

Coating is the process in which a ship is coated with special resin from the Yarukiman Mangroves. The coating gives the ship a jelly-like texture and a bubble-like luster. Once coated, the ship becomes less buoyant than the water around it, causing it to sink. Coating is a very delicate procedure and must be done carefully, for if a mistake is made, the ship may be crushed by the pressure. It is unknown how coating is done on a ship, though Silvers Rayleigh has been shown carrying several tools presumably related to its application, including an oversized brush.

Coating Mechanics
A coating mechanic is a person who coats a ship with the special resin that allows it to submerge. It is an expensive job and can take several days to complete. This is because if the job is done poorly, the ship might break with the pressure. So far only one coating mechanic has been identified in One Piece: Silvers Rayleigh.

Using a coated ship
Once a ship is coated, it loses the ability to stay afloat. Until the ship is read to depart, an air-filled 'floating bag' is used to keep it on the surface. Once the ship is ready to leave, a valve connecting the bag to the resin bubble is opened, transferring the air into the bubble, causing it to cover the ship completely in order to provide breathable air for the crew. The completed bubble also serves to protect the entire ship from the extreme water pressure beneath the sea.

In the anime, the bubble is shown to pop when a ship reaches the surface once more, though this may have been done intentionally by the crew.

Navigating a coated ship
Once the floating bag is removed, the ship starts to sink. However it does not mean it will sink straight down. The ship is to be navigated by using the under water sea currents as it would use the wind on the ocean surface.

Coated Ships

 * Moby Dick
 * Red Force
 * Thousand Sunny