OCIMF_Mooring_Equipment_Guidelines_(Second_Edition)

Jack with

Gauge

L.

,

I

FIGURE 7.6: SIMPLIFIED BRAKE TEST KIT

7.5.6 Brake Holding Capacity

F - Line Pull

·I-L,

Required Jack Force

:FS

L~

Winch

Foundation

The primary brake should be set to hold 6()°7o of the mooring line's MBL. Since brakes may deteriorate
in service, it is recommended that new equipment be designed to hold 801170 of the line's MBL, but
have the capability to be adjusted down 10 6()"10 of the line's MBL. A drum brake holding capacity
of 80"10 MBL is also required by Lloyds, DNV and ISO Standard 3730 with the rope on the fLTst
layer. If a brake of an undivided drum is set to hold 801170 MBL on t.he first layer, it wUl hold
approximately 65/1]0 MBL on the third layer.

7.6 WINCH PERFORMANCE

The principle performance particulars for different size mooring winches should correspond to values
listed in Table 7.1. These are in general agr~ment with ISO Standard 3730. except for minimum
light line speed and in-service setting of brake.

7.6.l Rated pull (also called drum load or hauling load)

This is rhe pull that the mooring line can develop at tbe rared speed on the first layer. The listed
values correspond to approximately 30"10 of the line's minimum breaking strength. This value assures
adequate force to heave in against environmenr.al forces. On the other hand, it is low enough to
prevent line overstrcssing in th e stalled condition. considering that the stall pull is generally bigher
than the rated pull for mosl drive types.