A drilling procedure in which a sharply pointed bit attached to a cable is repeatedly picked up and dropped on the bottom of the hole.



Related Terms

BUOYED UP

Lifted by a buoy, especially a cable that has been lifted to prevent it from trailing on the bottom.

ANCHOR CHARGE

A procedure that allows several charges to be preloaded in a seismic shot hole; the bottom charges are fired first, and the upper charges are held down by anchors.

CABLE DRILLING

Rock drilling in which the rock is penetrated by percussion, at the bottom of the hole, of a bit suspended from a wire line and given motion by a beam pivoted at the center.

CENTER GIRDER

A vertical plate on the ship's centerline between the flat keel and inner bottom extending the length of the ship. Also called center vertical keel, CVK. Or center keelson.

CHAIN STOPPER

A device used to secure the chain cable when riding at anchor, thereby relieving the strain on the windlass

DEEP TANK

Tanks extending from the bottom or inner bottom up to or higher than the lowest deck

CENTER VERTICAL KEEL

A vertical plate on the ship's centerline between the flat keel and inner bottom extending the length of the ship. Also called center vertical keel, CVK. Or center keelson.

DRAFT MARKS

The numbers which are placed on each side of a ship at the bow and stern from the lower edge of the number to the bottom of the keel

FLOOR

Vertical transverse plate immediately above the bottom shell plating, often located at every frame, extending from bilge to bilge.

DOUBLE BOTTOM

Compartments at the bottom of a ship between inner bottom and the shell plating, used for fresh water, ballast water, fuel oil, etc

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