Section 2 Equipment Number
Clasification Society 2024 - Version 9.40
Clasifications Register Rules and Regulations - Rules and Regulations for the Classification of Naval Ships, January 2023 - Volume 1 Ship Structures - Part 3 Design Principles and Constructional Arrangements - Chapter 5 Anchoring, Mooring, Towing, Berthing, Launching, Recovery and Docking - Section 2 Equipment Number

Section 2 Equipment Number

Parent topic: Chapter 5 Anchoring, Mooring, Towing, Berthing, Launching, Recovery and Docking

2.1 Equipment Number calculation

2.1.1 The anchoring and mooring equipment specified in this Section is based on an ‘Equipment Number’ which is to be calculated as follows:

where
A = area, in m2, in profile view, of the hull, superstructures, houses, masts, etc. above the design draught which are within the Rule length of the vessel and also have a breadth greater than B/4. See also Vol 1, Pt 3, Ch 5, 2.1 Equipment Number calculation 2.1.2.
A t = transverse projected area, in m2, of the hull and of all superstructures, houses, masts, etc. above the design draught
Δ = displacement, in tonnes, of the ship at its design draught waterline.

2.1.2 Screens and bulwarks more than 1,5 m in height are to be regarded as parts of houses when determining A. Where a screen or bulwark is of varying height, the portion to be included is to be that length the height of which exceeds 1,5 m.

2.1.3 For ships which have a complex above water transverse profile due to the presence of large plated masts, mast trees, large radar equipment, etc. the equipment number may need to be specially considered.

2.1.4 The Equipment Number formulae for anchoring equipment as given in this Section are based on an assumed maximum current speed of 2,5 m/s, maximum wind speed of 25 m/s and a minimum scope of 6, the scope being the ratio between length of chain cable paid out and water depth. For ships with a Rule length, LR, greater than 135 m, the required anchoring equipment is also considered adequate for a maximum current speed of 1,54 m/s, a maximum wind speed of 11 m/s and waves with maximum significant height of 2 m.

2.1.5 The anchoring equipment required herewith is intended for temporary mooring of a ship within a harbour or sheltered areas when the ship is awaiting berth, tide, etc. It is designed to hold a ship only in good holding ground conditions such as to avoid dragging of the anchor. In poor holding ground, the holding power of the anchors would be significantly reduced.

2.1.6 It is assumed that under normal circumstances a ship uses only one bower anchor and chain cable at a time.

2.1.7 Where Owners require equipment for anchoring at depths greater than 82,5 m and up to 120 m, it is recommended that the requirements specified in Vol 1, Pt 3, Ch 5, 10 Anchoring equipment in deep and unsheltered water shall be complied with.

2.2 Novel ship design

2.2.1 Where a ship is of unusual form and proportions the requirement for equipment will be individually considered on the basis of the Rules.

Copyright 2022 Clasifications Register Group Limited, International Maritime Organization, International Labour Organization or Maritime and Coastguard Agency. All rights reserved. Clasifications Register Group Limited, its affiliates and subsidiaries and their respective officers, employees or agents are, individually and collectively, referred to in this clause as 'Clasifications Register'. Clasifications Register assumes no responsibility and shall not be liable to any person for any loss, damage or expense caused by reliance on the information or advice in this document or howsoever provided, unless that person has signed a contract with the relevant Clasifications Register entity for the provision of this information or advice and in that case any responsibility or liability is exclusively on the terms and conditions set out in that contract.