THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS

Guide for the Mooring of Oil Carriers at Single Point Moorings GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS DECEMBER 2010 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2010 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA

Foreword Foreword This Guide has been developed in response to industry requests for an optional ABS Class notation to address arrangements where an Oil Carrier is fitted with equipment enabling it to be moored to single point moorings. The requirements cover the parts of OCIMF (Oil Companies International Marine Forum) Recommendations for Equipment Employed in the Bow Mooring of Conventional Tankers at Single Point Moorings 4 th edition May 2007 applicable for the vessel as per IACS Recommendation 13 [(1984), Rev 1, July 2004] Standards for Ship Equipment for Mooring at Single Point Moorings The effective date of this Guide is the first day of the month of publication. ii ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010

Table of Contents GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS CONTENTS SECTION 1 General... 1 1 Application...1 3 Notation...1 5 Submission of Design Plans and Data...1 SECTION 2 Arrangements... 2 1 General...2 3 Bow Chain Stoppers...2 3.1 Number, Chain Cable Size, and Minimum SWL... 2 3.3 Location...2 3.5 Alignment...2 3.7 Securing...2 3.9 Structural Strength...3 3.11 Relation to Deck Structure...3 3.13 Fairing of Leading Edge...3 3.15 Testing...3 5 Bow Fairleads...3 5.1 Openings...3 5.3 Ships with Two Fairleads...3 5.5 Ships with One Fairlead...3 5.7 Shape...3 5.9 Number of Fairleads...3 5.11 Structural Strength...3 7 Pedestal Rollers...3 7.1 Position...3 7.3 Distance between the Bow Stoppers and Pedestal Roller... 3 7.5 Number and Angle...4 7.7 Structural Strength...4 9 Winches or Capstans...4 11 Winch Storage Drum...4 13 Materials...4 TABLE 1 Required Arrangements by Vessel Deadweight...2 ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010 iii

SECTION 3 Survey Requirements... 5 1 Annual Surveys...5 3 Special Periodical Surveys...5 iv ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010

Section 1: General SECTION 1 General 1 Application This Guide is applicable to conventional Oil Carriers fitted with equipment enabling them to be moored by the bow to single point moorings or moored in tandem to FPSO/FSO terminals. The application of this Guide to other types of tankers will be subject to special consideration. 3 Notation An Oil Carrier provided with mooring arrangements in accordance with the requirements of this Guide will be eligible to be assigned the Class Notation SPMA. 5 Submission of Design Plans and Data The following design plans and data are to be submitted: Plan showing the mooring arrangement with position of bow fairleads, bow chain stoppers, winches and capstans and pedestal rollers and winch storage drums, if applicable Details of bow chain stoppers Details of bow fairleads and their attachment to the bulwark Details of attachment to deck and supporting structure of the bow chain stoppers, winch or capstans and pedestal rollers and winch storage drums, if applicable. ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010 1

Section 2: Arrangements SECTION 2 Arrangements 1 General The vessel is to be fitted with bow chain stoppers and bow fairleads as per Section 2, Table 1. Additional pedestal roller fairleads may be required for alignment purposes and a winch or capstan for the pick-up rope. The requirements for the supporting deck structure in way of all equipment are to be in accordance with 3-2-7/4, 3-5-1/11, and 3-5-1/15 of the ABS Rules for Building and Classing Steel Vessels (Steel Vessel Rules). Ship Size (tonnes DWT at maximum summer draught) 100,000 or less (See Note) Over 100,000 but not greater than 150,000 (See Note) Over 150,000 Note: TABLE 1 Required Arrangements by Vessel Deadweight Chafing Chain Size 76 mm (3 in.) 76 mm (3 in.) 76 mm (3 in.) Number of Bow Chain Stoppers Minimum SWL (Tonnes) 1 200 tonnes (440405 lbs) 1 250 (550505 lbs) 2 350 (770707 lbs) Ships in this size range may elect to fit two stoppers / fairleads to ensure full range terminal acceptance Number of Bow Fairleads (recommended) 1 1 2 3 Bow Chain Stoppers 3.1 Number, Chain Cable Size, and Minimum SWL The number, chain cable size, and minimum SWL of bow chain stoppers are to be in accordance with Section 2, Table 1. The chain stoppers are to be permanently marked with the SWL to which they have been designed and tested. 3.3 Location Bow chain stoppers are to be located between 2.7 m (8 ft 10 1 / 4 in.) and 3.7 m (12 ft 1 3 / 4 in.) aft of the bow fairlead. 3.5 Alignment Stoppers are to be positioned to give correct alignment with the bow fairlead and the pedestal fairlead or storage drum of the winch. 3.7 Securing A standard 76 mm (3 in.) stud-link chain is to be secured when the chain engaging pawl or bar is in the closed position. When in open position, the chain and associated fittings are to be allowed to pass freely. 2 ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010

Section 2 Arrangements 3.9 Structural Strength The structural strength of the stopper and supporting structure is to be in accordance with 3-5-1/11 of the Steel Vessel Rules, when applying a load equal to the SWL given in Section 2, Table 1. 3.11 Relation to Deck Structure Stoppers are to be fitted as close as possible to the deck structure, taking due consideration to possible obstacles in order to obtain a free lead through the fairleads. 3.13 Fairing of Leading Edge The leading edge of the bow chain stopper base is to be faired to allow for the unimpeded entry of the chafing chain. 3.15 Testing Upon installation, bow stoppers are to be load tested to the equivalent SWL in the presence of our surveyor and a test certificate is to be issued. The test certificate is to be available for inspection onboard the ship. Applicable strength of the supporting structure is to be documented by adequate analyses and submitted for review to a technical office. A copy of the approval letter in such cases is to be available onboard. 5 Bow Fairleads 5.1 Openings Bow fairlead openings are to measure at least 600 mm 450 mm. (23 1 / 2 in. 17 3 / 4 in.) 5.3 Ships with Two Fairleads For ships fitted with two fairleads, they are to be spaced, from center to center, at least 2.0 m (6 ft 6 3 / 4 in.) apart. In any event, the fairleads are not to be spaced more than 3.0 m (9 ft 10 in.) apart. 5.5 Ships with One Fairlead For ships fitted with one fairlead, it is to be positioned on the centerline. 5.7 Shape Fairleads are to be oval or round in shape and adequately faired when fitted in order to prevent chafing chains from fouling on the lower lip when heaving inboard. Square fairleads are not suitable. 5.9 Number of Fairleads When two bow chain stoppers are fitted, then two bow fairleads are required. 5.11 Structural Strength The structural strength of the bow fairlead is to be based on a safety factor of 2.0 against the yield criterion when applying a load equal to SWL given in Section 2, Table 1. 7 Pedestal Rollers 7.1 Position Winches or capstans are to be positioned to enable a direct pull to be achieved on the continuation of the direct lead line between the bow fairleads and bow stoppers. Alternatively, a pedestal roller may be positioned between the stopper and the winch or the capstan, in order to achieve direct pull. 7.3 Distance between the Bow Stoppers and Pedestal Roller The distance between the bow stoppers and pedestal roller is to be considered so that an unrestricted line pull is achieved from the bow fairlead and through the bow stopper. ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010 3

Section 2 Arrangements 7.5 Number and Angle The number of pedestal rollers used for each bow chain stopper is not to exceed two and the angle of change of direction of the pick-up rope lead is to be minimal. 7.7 Structural Strength The structural strength of the pedestal rollers and supporting structure is to be in accordance with 3-5-1/15 of the Steel Vessel Rules when applying a load equal to the SWL given in Section 2, Table 1. 9 Winches or Capstans Winches or capstans are to be capable of exerting a continuous duty pull of not less than 15 tonnes (33030 lbs). 11 Winch Storage Drum If a winch storage drum is used to stow the pick-up rope, it is to be of sufficient size to accommodate 150 m (492 ft) of 80 mm (3 3 / 16 in.) diameter rope. 13 Materials Material for the hull structure is to be in accordance with Chapter 1 of the ABS Rules for Materials and Welding (Part 2). Material for the deck fittings will be accepted on the basis of the manufacturer s certified mill test reports. 4 ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010

Section 3: Survey Requirements SECTION 3 Survey Requirements 1 Annual Surveys Chain stoppers and fairleads, including foundations, are to be examined. 3 Special Periodical Surveys Chain stoppers, fairleads, winches, capstans, and other deck fittings, including all foundations, are to be examined and operationally tested. ABS GUIDE FOR THE MOORING OF OIL CARRIERS AT SINGLE POINT MOORINGS. 2010 5