Load Lines


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Load Lines

A marking indicating the extent to which the weight of a load may safely submerge a ship; also called Plimsoll line.

The load line, or Plimsoll mark, is positioned amidships on both sides of a vessel. Its purpose is to indicate the legal limit to which a ship may be loaded for specific ocean areas and seasons of the year. The basic Load Line Certificate is issued after a complex calculation is made to determine exactly where the Plimsoll mark should be positioned. These certificates take several forms, such as international voyage, coastwise traffic, and Great Lakes operations.

By calculating the load line, the agency issuing a certificate has determined, among other aspects of seaworthiness, that a vessel has enough volume of ship (reserve buoyancy) above the waterline so that it will not be in danger of foundering or plunging when under way in heavy seas. In the United States the U.S. Coast Guard issues load line regulations; routine assignment of load lines is handled by the American Bureau of Shipping.

A series of multilateral treaties has been executed to impose on signatories the responsibility of seeing that ships flying under their flag have safe load lines designated and that they are observed. The principal treaty is the International Convention on Load Lines 1966. The use of load lines on vessels sailing under the flag of the United States is mandated by federal law (46 U.S.C.A. 86 [1973]). The treaties typically do not apply to ships of war, small ships, pleasure boats, and fishing vessels.

References in periodicals archive ?
Given a required RF output power level, any decrease in supply voltage requires a corresponding increase in current, a larger transistor and an output load network with a higher conductance load line. While the higher conductance load line can be achieved by a network providing a larger impedance transformation (impedance scaling), the RF losses associated with this network are higher unless the Q of the individual components can also be increased.
As expected, such losses are more dominant with increased device size and load line conductance.
The Load Lines Convention aims to prevent the ship's overloading by prescribing the minimum reserve buoyancy and freeboard of ships.
'As a nation with a long history of sea tragedies, the Philippines has recognized the important role of the Load Lines Convention as a major pillar of maritime safety by preventing the overloading of ships through the presence of visible load line marks,' Legarda said in a statement.
These load lines are only approximate, since the PBT is not really a constant [g.sub.m] or linear [g.sub.m] device.
An alternative approach might be to take some average component value, using either a simple time average, or using a state space average, as employed in power supply design.[6] A third approach that has been used to get accurate results with FETs is to bias the device in the middle of its I-V characteristics, halfway up the load line for Class A operation.
In order to be able to choose the proper load impedance for maximum output power, a digression to discuss output power and load lines is required.