Oil Fuel Outflow

This module calculates the mean oil outflow parameter in accordance with "MARPOL, ANNEX 1 Regulation 12A - Oil fuel tank protection", paragraph 11, and compares this to the standard required.

Paragraphs 6, 7 and 8 of Regulation 12A, specify the location of fuel oil tanks to minimize the risk of pollution in the event of damage to the vessel. Paragraph 11 provides an alternative method of evaluating the risk pollution based on probabilistic principles. This module is only concerned with this alternative method.

Note:
MARPOL ANNEX 1 Regulation 12A only applies to ships with an aggregate oil fuel capacity greater than 600 m3.

The module calculates the mean oil outflow for side and bottom damage (Oms and Omb) and combines them into a mean oil outflow index, Om = (0.4Oms + 0.6Omb)/C, where C is the total fuel oil capacity of the vessel.

The mean oil outflow index must be less than 0.0157 - 1.14E-6.C, where C < 5000 m3, or 0.010, where C >= 5000 m3.

The mean outflow for side damage, Oms, is calculated as the sum of Ps.Os for each tank, where Ps is the probability of penetrating the oil fuel tank, calculated from tables given in the rules, and Os is the outflow, in m3, from side damage.

Similarly, the mean outflow for bottom damage, Omb, is calculated as the sum of Pb.Ob.Cdb for each tank, where Pb is the probability of penetrating the oil fuel tank, calculated from tables given in the rules, Ob is the outflow, in m3, from bottom damage, and Cdb is a factor to account for oil capture, which is 0.6 if the tank is bounded below by non-oil tanks, and 1.0, if not.

For bottom damage, the ship is assumed to be grounded, and consequently, Obm depends on the tidal change. For the regulations, outflow due to bottom damage is calculated at two tide conditions, zero and minus 2.5 m, and Omb = 0.7 Omb(0) + 0.3 Omb(2.5)

There are also special rules concerning tanks bounded by the bottom shell. In practice, this may mean that ships with fuel oil tanks in the double bottom, are unlikely to comply with Regulation 12A.

The capacity of a single oil fuel tank shall not exceed 2500 m3.

Sample output from Oil Fuel Outflow module