The term sea chest is used for a rectangular or cylindrical recess in the

hull Hull may refer to: Structures * The hull of an armored fighting vehicle, housing the chassis * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a sea-going craft * Submarine hull Ma ...

of a

ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...

Ship's reservoir/filter

The sea chest provides an intake reservoir from which piping systems draw raw water. Most sea chests are protected by removable

grating A grating is any regularly spaced collection of essentially identical, parallel, elongated elements. Gratings usually consist of a single set of elongated elements, but can consist of two sets, in which case the second set is usually perpendicu ...

s, and contain baffle plates to dampen the effects of vessel speed or sea state. The intake size of sea chests varies from less than 10 cm² to several square metres.

Zebra mussel control in sea chests

When the ship is in

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

, the hard steel surfaces of the sea chest, protective grates and baffles, combined with low water velocities created in this immediate area, provide a suitable environment for

zebra mussel The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...

attachment. Zebra mussel infestations have been found to clog the individual intakes and gates of the various water piping systems, decreasing the availability of water for onboard operations, which could result in damage to engines and other components that require water for cooling. Sea chests are, therefore, considered to be the most susceptible component to serious infestation. Control strategies include coating all surfaces with an antifoulant such as

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

-based epoxy paint or

hot-dip galvanizing Hot-dip galvanization is a form of galvanization. It is the process of coating iron and steel with zinc, which alloys with the surface of the base metal when immersing the metal in a bath of molten zinc at a temperature of around . When expos ...

. Periodic inspection and replacement of grates and screens also reduces the risk. Increasing the size of the sea chests by 20% to 30% may delay the onset of serious problems that could force an engine shutdown. Thermal treatment is a highly effective strategy for the control of zebra mussels (McMahon et al. 1995). Thermal treatment may include retrofitting a closed loop system to recirculate the heated water to the sea chest or the addition of a second sea chest system, allowing engine cooling water to be discharged through the idle sea chest. Recirculation of engine cooling water as a thermal control strategy has proved extremely effective in controlling zebra mussels (Palermo 1992, U.S. Coast Guard 1994).

References

* This article uses public domain text taken directly from

{cbignore, bot=medic Shipbuilding Nautical terminology