- Locate bow and stem fairleads as far forward and aft and as low as possible on the sh.ip.
- Locate spring line fairleads as far forward and aft on the main deck as possible to provide
adequate line lengths to spring mooring points on the berth. - Stress the need for correct alignment between fairleads (or chocks) and winch drums.
- Locate winch control positions to provide a clear view of the mooring operations and the
officer-in-charge of mooring. - Mooring lines in the same service should have about the same lengtb between the vessel's
winch and its chocks. - All mooring !.ines should be capable of being run to either side of the vessel.
3.2.1 Number and Size of Lilies
Before any mooring layout can be considered, the Dumber, material and size of lines must be deter-
mined. This can best be done by computer analysis. However, Section 2 provides approximate
methods to determine t he product of li ne quantity x line breaking load for standard environmental
conditions. This is given for breast lines and spring lines separately, as 'B x MBL' and'S )( MBL',
where 'B' is the total number of breast lines and'S' the total number of spring lines. Once the
product of either '8 x MBL' or'S x MBL' is determined. 'B', 'S' and 'MBL' must be balanced using
tbe foUowing guidelines:- Select the most appropriate material on the basis of s[rength, elasticity, durability and handling
characteristics. SIXtion 6 provides general guidelines for tbe selection of mooring line materials
and line construction. - Ma.ximum nexibility is provided if all lines are of [he same size and material (as mentioned
in Section 1.5). - Select the lar gest line that can safely be bandied by ship and termi nal personnel. For wire
rope, 44 mm diameter is considered a working maximum based on operators' experience.
altbougll 48 mm diameter wire ropes are used on occasion. For libre rope, 80 mm diameter
(10 inches in circumference) is considered a praC1ical maximum for ship-supplied hawsers.
There are practical minimums fOT the number of lines as given in the next paragraph, and
there is no need to select an M.Bl higher than required to comply with the ' B x MBL' or
'S x MBL' criteria. - To provide a symmetrical arrangement about mldsmps, '8' and'S' should be even numbers.
Four is considered a practical minimum for the number of spring lines (to provide two lines
in each direction). Likewise, four is a practical minimum for breast lines to provide two lines
each al the bow and the stern. If an uneven number of breast lines is utilized, the eXlra line
shouJd generaUy be attached to t.he stern, since the standard environmental criteria given in
Section 2 produces an aft Iransvcrse force .bs[ is about 100J0 higher than the forward one. - The considerations discussed above assume that mooring lines can be issued at eitber port or
starboard side of tbe ship and that all lines are pennanently stowed on winch drums. If the
arrangement of winches and fairleads does not allow this, or tbe terminal or trading panem
dicta[es otherwise, addition.al lines (and winches) would be required. - In addition to tbe recommendations on mooring Line sizes and quantities listed above, the
designer as well as the ship operator must consider the generalised mooring equipment require-
menlS stipulated by termioals. Sometimes tbese requirements are based on past experience with
inefficient mooring equipment (such as mixed material moorings) and may demand more lines
than required for a ship with e.fficient and weU-maintained mooring equipment. In such cases,
the ship owner complying with the recommendations of this Guide may strongly represent to
the terminal operator that his ship provides an outfit able to securely moor the ship in specific
conditions, citing the Guide as grouods for its acceptance.