Page 376 - International safety guide for oil tankers and terminals

INTERNATIONAL SAFETY GUIDE FOR OIL TANKERS AND TERMINALS

definition, will render under load and will allow the vessel to move
out of position, with consequent risk to cargo arms or hoses.
adrift from berths as the result of slipping winch brakes.---

23.4.2.3 Self-Stowing Mooring Winches
The physical condition of the winch gearing and brake shoeิชย์นาวี
Because their weight and size make manual handling difficult,
mooring wires used by large tankers are normally stored on
---ใช้เพื่อการศึกษาเท่านั้น
self-stowing mooring winches, which may be either single drum or
split drum. Some features of these winches need to be clearly
understood by ship’s personnel in order to avoid tankers breaking

The design holding power of the brake may either have been
specified by the shipowner or be the standard design of the winch
manufacturer. Every ship’s officer should be aware of the
งานห้องสมุด ศูนย์ฝกพาณ
designed brake holding capacity of the self-stowing mooring
winches installed on the ship.

linings or blocks has a significant effect on brake holding capacity
in service. Mooring winch brakes should therefore be tested at
regular intervals, not exceeding twelve months. A record, both of
regular maintenance and inspections and of tests, should be kept
on the ship. If the deterioration is significant, the linings or blocks
disc brakes, which are less affected by wear. ึ
must be renewed.
Some of the newer self-stowing mooring winches are fitted with

Kits are available for testing winch brake holding capacity and can
be placed on board for use by the crew.

In addition, there are a number of operational procedures that can
seriously reduce the holding capacity of winch brakes if they are
not correctly carried out. These include:

The Number of Layers of Wire on the Drum
The holding capacity of a winch brake is in inverse proportion to
the number of layers of the mooring wire or rope on the drum.
The designed holding capacity is usually calculated with reference
to the first layer and there is a reduction in the holding capacity for
each additional layer. This can be substantial – as much as an
11% reduction for the second layer.

If the rated brake holding capacity of a split drum winch is not to
be reduced, only one layer should be permitted on the working
drum.

The Direction of Reeling on the Winch Drum
On both single and split drum winches, the holding power of the
brake is decreased substantially if the mooring line is reeled on
the winch drum in the wrong direction. Before arrival at the berth,
it is important to confirm that the mooring line is reeled so that its
pull will be against the fixed end of the brake strap, rather than the
pinned end. Reeling in the contrary direction can seriously reduce
the brake holding capacity, in some cases by as much as 50%.
The correct reeling direction to assist the brake should be
permanently marked on the drum to avoid misunderstanding.

342 © ICS/OCIMF/IAPH 2006