OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

formulae listed in Section 2.6. For instance, assuming an efficiency of 90070 for eiJner forward or
aft spring lines, and 70070 for either forward or aft breast lines, and further assuming that the
maximum. allowable load in a line is 55070 of a line's minimum breaking load, the requirement would
be as [01.l0W5:

Spring lin.es, either forward or aft: S )( MBL

Forward breast lines: BR )( MBL

A ft breast Ii nes: BR x MBL

F., ma>:.

= 2.0 F, mux.

0.9 )( 0.S5

F,I' max.

= 2.6 Fyl' max.

0.7 )( 0.55

PI' A max.

= 2.6 F yA ma't.

0.7 )( 0.55

Symbols are th e same-as used in Sections 2.3 and 2.6, except that !.he number of lines (S, BR)
rela~es to the iudjvidual groups Ii. ted above.

The maximum force components (F, max., Fyf mall., F"A max.) under the standard environmental
criteria can be calculated by formulae (7) to (15) in Section 2.4.1 for oil tankers, and by formulae
(16) to (21) in Section 2.4.2 for gas carriers.

This method assumes Ihat the mooring layout complies with good principles as mentioned above for
the more involved hand calculation method.

2.5.4 Standard Restraint Requirements

To obtain a uniform standard of mooring equipment for tankers not designed for a specific trade
or terminal. it is recommended that a ship designer:

1. Follow the principles provided in Section 3 regarding the placement of winches, chocks, and
   fairJeads.


2. Assume breast lines to be at an angle of 750 to the longitudi:nal axis of the shj.p. A horizontal
   angle of 100 to the side of the vessel shOuld be assumed for spring lines. Maximum vertical
   angles of 250 should be assumed for the lightest ballasted condjtion. These crHcria therefore
   determine the position of nlOoring poiJtlS for an idealised mooring line layout. Figure 2.10
   illustrates the layout.


3. Calculate the number of breast lines and spring lines that would be required for the "Standard
   Environmental Criteria" and for the idealised mooring layout as discussed in I and 2 above.