COMPANY SHIP TO SHIP OIL TRANSFER OPERATIONS PLAN
M/T “VSLNAME“ PAGE 48 OF 96
Flow rates for different hose velocity ranges can be calculated using the following formula: (πr2Vx 3600 = cubic meters per hour) Where r2 is the internal radius in meters and V is flow velocity in meters per second. 3.8.3. Mooring Equipment It is important that both ships are fitted with good quality mooring lines, efficient winches, well placed and sufficiently strong closed fairleads, bollards and other associated mooring equipment which are fit for purpose. Effective leads between fairleads and mooring bitts and mooring winches should be available for the handling of all mooring lines. Only fairleads of the enclosed type should be used, except on a ship that will always have a substantially greater freeboard than the other. This will ensure that the fairleads will remain effective in controlling mooring line leads as the freeboard difference between the two ships changes. Such fairleads should be strong enough to take the anticipated mooring loads and large enough to allow the mooring line (plus any soft rope tail and shackle) to pass through comfortably. Open fairleads, even those fitted with stopper bars, are not recommended for STS operations. A prime consideration in mooring during STS operations is to provide fairleads and bitts for all lines without the possibility of lines chafing against each other, the ships, or the fenders. This is critical in view of the large relative freeboard changes between the ships. Steel wire mooring lines should be fitted with synthetic fibre tails to provide the additional elasticity and electrical discontinuity required for STS mooring arrangements, and also to permit cutting in an emergency. Lengths, connections and properties of such synthetic fibre tails should at least comply with the recommendation of the OCIMF Mooring Equipment Guidelines. Some dedicated lightering ships may be equipped with special mooring line arrangements such that the synthetic fibre tail is of a different length to the Mooring Equipment Guidelines recommendations and is positioned outside the ship's fairleads with a further wire pendant attached to its end to reduce chafing damage. High modulus synthetic fibre ropes, which are now increasingly being used as ship's moorings, should (depending on type) also be fitted with soft rope tails to provide additional elasticity and to reduce the susceptibility to fatigue failure. (See the OCIMF publication Guidelines on the Use of High-Modulus Synthetic Fibre Ropes as Mooring Lines on Large Tankers for further details.) Some high modulus synthetic fibre ropes are susceptible to axial compression fatigue due to tight radius bends and care should be taken to follow the manufacturer's recommendations when choosing the connection to the tail. Some types are more susceptible to chafing and may require greater protection in STS service. Strong rope messengers should be available on both ships. A rope messenger is a light rope that is used for hauling mooring lines between ships. A minimum of four messengers should be available, preferably made from a buoyant synthetic fibre material of 40mm diameter and at least 200m in length and fit for purpose. It is recommended that the guidance provided for sizing, marking and certifying fairleads and bollards should be applied to these fittings. Further guidance is provided in the OCIMF Mooring Equipment Guidelines and Recommendations for Ships' Fittings for Use with Tugs; in particular Section 4.3.1 Recommendations for the Tanker Owner, should be applied to such fittings used for STS moorings. In so doing, it is recognized that it may not always be practicable to apply all aspects of these recommendations to existing mooring equipment with the ship in active service and that changes may have to wait for a dry-docking or repair period. In the case of existing ships where deck Issue No. 1
Issue Date: 30/07/2010
Amendment No. 0
Amendment Date: 30/07/2010