9 The maximum permissible mean outflow parameter

  9.1 A parametric series of 96 designs were evaluated in order to assist in establishing the maximum permissible outflow values. Nine ship sizes were considered, ranging from 5,000 to 460,000 tons deadweight. For each size, a series of designs were evaluated covering variations in cargo tank arrangement, and wing tank and double bottom clearances. Outflow calculations assume the nominal double bottom and wing tank clearances are maintained through the cargo block. When calculating the probabilities of breaching cargo tanks, a simplified prismatic hull shape is assumed.

  9.2 The mean outflow parameters are displayed as a function of the cargo capacity in figure 15. In table 1, designs are sorted by mean outflow parameter. The cargo tank arrangement and nominal double hull dimensions are also listed in table 1. For example, "5x2 1x1.1", refers to a design with cargo tanks arranged two wide and five long; with a 1.0 m wing tank width, and a 1.1 m double bottom height. The simplified approach was also evaluated on a series of actual tankers (refer to part A, section 6.4 of these Explanatory Notes for details).

  9.3 Figure 16 shows the maximum permissible mean outflow parameter for oil tankers and combination carriers of 5,000 metric tons deadweight and above. The criterion for combination carriers may be applied if calculations demonstrate that the increased structural strength of the combination carrier provides outflow equivalency at least equal to a standard double hull tanker of equal size.