Classification alert: Anchoring, Mooring and Towing (IACS UR A1, A2 & Rec 10).
28 June 2018
Applicability: Ships classed under Lloyd’s Register (LR) Ship Rules and Naval Ship Rules
The International Association of Classification Societies (IACS) has revised the requirements and recommendations provided by the following instruments:
Unified Requirement A1- Anchoring Equipment
Unified Requirement A2- Shipboard fittings and supporting hull structures associated with towing and mooring on conventional ships
Recommendation 10- Anchoring, Mooring and Towing Equipment
Considering the fact that these IACS instruments were revised with the intention of promoting safe mooring, safe towing and effective anchoring, LR proposes incorporating these requirements into the following Rule sets, with effect from 1 July 2018.
- Rules and Regulations for the Classification of Ships
- Rules and Regulations for the Classification of Naval Ships
Anchor wire rope
The updates to Ship Rules would include the requirements to be complied with when the chain cable attached to the bower anchor is replaced with wire rope. It should be noted that the option of using wire rope in lieu of anchor chain cable is restricted to vessels with a Rule length of less than 40 metres.
Anchoring in deep and unsheltered water
Provisions have also been made to acknowledge anchorages outside ports due to high volumes of traffic, and those that are subject to increased environmental loads.
This upcoming section of the Rules can be used to assess the adequacy of the anchoring equipment for ships with Rule length of no less than 135 metres that are intending to anchor in water of depths up to 120 metres, with current speeds of up to 1.54 m/s and winds up to 14 m/s, and where the significant wave height is no greater than 3 metres.
Please note that compliance with deep water anchoring recommendations is not mandatory and they do not replace the conventional anchoring requirements specified in the Rules. Also, they are recommended only for ships with a Rule length of no less than 135 metres that intend to anchor in water of depths up to 120 metres.
The current prescriptive recommendations on mooring are to be replaced with analytical procedures, as provided by IACS Recommendation 10. These changes could have an impact on the minimum recommended number of mooring lines and their required breaking strength, depending on the ship type and its design features. These updates will also include recommendations on mooring arrangements and mooring winches.
Shipboard fittings (Mooring and Towing)
The updates to ship board fittings and supporting hull structures associated with towing and mooring on conventional ships are summarised below:
- Changes to the design load applied to the mooring fittings.
- Detailed guidance on the selection of shipboard fittings from a recognised standard.
- Design criteria, corrosion addition and wear allowance for shipboard fittings when not selected from an industry standard.
- Finite Element Analysis procedure for the design of the supporting hull structure for the shipboard mooring and towing fittings.
- The introduction of TOW (Safe Towing Load), computed in accordance with the unified requirement, which is to be marked on the deck fittings used for towing.
- Revised requirements for the towing and mooring arrangement plan.
What should owners and operators do now?
Shipowners, designers and builders need to be aware that these updated requirements are applicable to ships contracted for construction on or after 1 July 2018.
The Rule amendment notices for both Ship Rules and Naval Ship Rules would be issued in the month of February 2018, with effect from 1 July. The amendment notices can be referred to for further details.
The revised IACS Unified Requirements A1, A2 and Recommendation 10 along with their technical background is publicly available for reference on the IACS website.