If this double bottom is not fitted, SOLAS provides a deterministic damage stability standard for demonstrating that the design has a sufficient level of safety against bottom damage. The double bottom is a watertight deck in the lower part of the hull and it serves as a redundant barrier in case of grounding or underwater damage. Then, for all loading conditions the operational point of the ship must lie in the admissible part of Figure 11.6, an adaptation of Figure 8.4.īetween transverse bulkheads but not less than 3 mĪccording to SOLAS, vessels should be designed with a double bottom extending from the aftermost to the foremost bulkhead. For intermediate draughts, the values to be used shall be obtained by linear interpolation of GM ¯ values only between the deepest and the partial subdivision draught, and between the partial load line and the light service draught. The minimum required GM ¯ value (or, alternatively, the maximum permissible KG ¯ value) for the three draughts d s, d l, and d p are equal to the GM ¯ (or KG ¯) values corresponding to the loading cases considered for the calculation of the survivability factor, s i.

The formulation for cargo ships is different from that for passenger ships. This survivability factor depends on the heel angle, the maximum GZ ¯-value, and the positive range of the GZ ¯-curve. The expression of the survivability factor, s i, is a general formulation designed to represent the probability that the ship may survive the flooding of a compartment or group of compartments. The p i factor represents the probability that a compartment or group of compartments may be flooded, disregarding horizontal subdivision it is based upon the examination of collision cases for which information on both damage penetration and damage longitudinal extent was available. The rest can move on, well, ships with flags of convenience.The subdivision is considered sufficient if the attained index, A, is not less than the required subdivision index, R, calculated according to the regulations, and if, in addition, the partial indices A s, A p, and A l are not less than 0.9 R for passenger ships, and 0.5 R for cargo ships. In addition, there are some categories of cargo, typically aid or agricultural cargoes, where only a portion of the cargo has to move on U.S. crew on the Danish line-operated ship Maersk Alabama in 'Capt.

And these carriers have to follow some of the U.S. flags on portions of their fleet in exchange for a retainer and a guarantee of ship space when needed. get its cargo around the world? Some foreign lines are allowed to fly the U.S. shipping companies in existence today only serve domestic routes (think Hawaii and Puerto Rico). does not have enough home-grown shipping capacity to handle all its cargo. And so over the decades laws have been enacted to require just that.īut that has led to another problem: The U.S.

Many folks, particularly members of Congress representing areas with shipyards and seafarers, believe those cargoes should move on U.S. has a lot of government-related cargo moving around the world, like military supplies or disaster relief aid funded by U.S. So most ship lines go for 'flags of convenience.' These are the flags from countries that typically have no restrictions on what nationality your crew should be (or how much they should be paid) or where your ship should be built or repaired.

Cargo vessel meaning