A wooden lattice-work covering a hatch or the bottom boards of a boat; similarly designed gratings of metal are frequently found on shipboard.

see Bream

The middle watch.

The efficiency of the filter in removing some portion of a specified test contaminant under a specific set of laboratory conditions. It determines the mass of the contaminant the filter removes from a known sample introduced to the filter.

The largest circle which can be inscribed on a sphere by a plane that cuts through the center of the sphere. On the earth, the equator is a great circle, as are all the meridians of longitude which pass through both poles. The shortest distance between tw ...

A can buoy. A cylindrical buoy painted green and having an odd number used in the United States as a navigational aid. At night they may have a green light. Green buoys should be kept on the left side when returning from a larger body of water to a smalle ...

A navigational aid used in the United States and Canada to mark a channel. Green triangular daymarks should be kept on the left when returning from a larger to smaller body of water.

A large body of water taken aboard (ship a sea).

GMT for short. Greenwich Meridian Time, also known as Universal Time or Zulu time. A time standard that is not affected by time zones or seasons. It is the time used by navigators in celestial navigation.

Rum diluted with water. In the 1700s the daily ration of rum in the British Navy was diluted with water with the idea of reducing drunkenness. The term groggy was derived from the effects of drinking too much grog.

Gross tonnage is the basis on which manning rules and safety regulations are applied, and registration fees are reckoned. Port fees are also often reckoned on the basis of GT and NT. GT and NT are defined according to formulas which take account, among ot ...

Freight money collected or to be collected without calculating the expenses relating to the running cost of the ship for the voyage undertaken.

A common measurement of the internal volume of a ship with certain spaces excluded. One ton equals 100 cubic feet; the total of all the enclosed spaces within a ship expressed in tons each of which is equivalent to 100 cubic feet.

Applies to vessels, not to cargo, (0.2+0.02 log10V) where V is the volume in cubic meters of all enclosed spaces on the vessel.

Entire weight of goods, packaging and freight car or container, ready for shipment. Generally, 80,000 pounds maximum container, cargo and tractor for highway transport.

To touch bottom.

Long wave formations during calm or light air formed by waves running into shoaling water

A term used to cover all of the anchor gear.

Running ashore (hitting the bot-tom).