Term
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Definition
| The widest point of a vessel on a line perpendicular to the keel, the fore-and-aft centerline. |
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Term
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Definition
A line secured from the bow of a vessel. In an alongside towing operation, the bow line is
secured on both the towing and the towed vessel at or near the bow and may act as breast
line of each. |
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Term
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Definition
| The tendency or capacity of a vessel to remain afloat. |
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Term
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Definition
Point in a ship where the sum of all moments of weight is zero. With the ship at rest, the
center of gravity and the center of buoyancy are always in a direct vertical line. For surface
ships, center of buoyancy is usually below center of gravity, and the ship is prevented from
capsizing by the additional displacement on the low side during a roll. Thus the point at
which the deck edge enters the water is critical because from here onward, increased roll
will not produce corresponding increased righting force. |
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Term
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Definition
A hull that achieves its buoyancy or flotation capability by displacing a volume of water
equal in weight to the hull and its load. |
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Term
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Definition
The point on a vessel’s underwater body, measured from the waterline, that reaches the
greatest depth. |
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Term
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Definition
| Forces associated with the changing environment e.g., the wind, current, weather. |
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Term
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Definition
| Forces that affect the horizontal motion of a vessel; they include wind, seas and current. |
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Term
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Definition
A tidal effect caused by the rise in water level in a river, bay, or estuary immediately
followed by a high tidal condition. |
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Term
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Definition
Any of the members of the skeletal structure of a vessel to which the exterior planking or
plating is secured. |
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Term
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Definition
| The upper edge of a boat’s side. Pronounced “gun-ul.” |
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Term
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Definition
Temporary leaning of a vessel to port or starboard caused by the wind and sea or by a high
speed turn. |
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Term
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Definition
| The body or shell of a ship or seaplane. |
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Term
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Definition
| A propulsion device that draws water in and forces it out through a nozzle. |
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Term
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Definition
The towing boat keeping the proper position with the towed boat. For example; the proper
distance in relation to sea/swell patterns so that both boats ride over the seas in the same
relative position wave crest to wave crest. |
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Term
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Definition
The central, longitudinal beam or timber of a ship from which the frames and hull plating
rise. |
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Term
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Definition
2000 yards; Length of one minute of arc of the great circle of the earth; 6,076 feet
compared to 5,280 feet per a statute (land) mile. |
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Term
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Definition
The position of two boats (i.e., towing operations) where one boat is on the top of the crest
of a wave and the other is in the trough between the waves. |
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Term
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Definition
The vertical motion of a ship’s bow or stern in a seaway about the athwartships axis. Of a
propeller, the axial advance during one revolution. (see roll, yaw) |
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Term
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Definition
Vessel motion caused by a wave lifting up one side of the vessel, rolling under the vessel
and dropping that side, then lifting the other side and dropping it in turn. |
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Term
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Definition
Rotary oscillation about a ship’s vertical axis in a seaway. Sheering off alternately to port
and starboard. |
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Term
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Definition
| Distance from the weather deck to the waterline on a vessel. |
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