Requirements for Emergency towing arrangement

 

Requirements for Emergency Towing Arrangements & its Components:

• The emergency towing arrangement should be so designed to facilitate salvage and emergency towing operations on tankers primarily to reduce the risk of pollution.

• Designs of emergency towing arrangements should be prototype tested to the satisfaction of the administration. 

• The arrangements should be at all times be capable of rapid deployment in the absence of main power on the ship to be towed and easy connection to the towing vessel.

Towing Components: 

        The major components of the towing arrangements should consist of the following:

Components	Forward of the Ship	Aft of the Ship
Pick-up Gear	Optional	Required
Towing Pennant	Optional	Required
Fairlead	Required	Required
Strongpoint	Required	Required
Roller Pedestal	Required	Depending on design
Chafing Gear	Required	Depending on design

Strength of Towing Components:

• Towing Components should have a working strength of at least 1,000 KN for tankers of 20,000 tonnes deadweight and over but less than 50,000 tonnes deadweight, and at least 2,000 KN for tankers of 50,000 tonnes deadweight and over.

• The strength should be sufficient for all relevant angles of the towline, (i.e.) up to 90 degrees from the ship's centreline to port and starboard and 30 degrees vertical downwards.

• Other components should have a working strength sufficient to withstand the load to which such components may be subjected during the towing operations.

Length of Towing Pennant:

        The towing pennant should have a length of at least twice the lightest seagoing ballast freeboard at the fairlead plus 50 metres.

Location of Strongpoint and Fairleads:

        The bow and stern strongpoint and fairleads should be located so as to facilitate towing from either side of the bow or stern and minimize the stress on the towing system.

Strongpoint:

• The inboard end fastening should be a stopper or bracket or other fittings of equivalent strength.

• The strongpoint can be designed integral with the Fairleads.

Fairleads:

• Fairleads should have an opening large enough to pass the largest portion of chatting gear, towing pennant or towing line. 

• The Fairlead should give adequate support from the towing pennant during towing operation which means bending 90 degrees to port and to starboard side and 30 degrees vertical downwards.

• The Fairlead should be located as close as possible to the deck and, in any case, in such a position that the chafing chain is approximately parallel to the deck when it is under strain between the strongpoint and the fairleads.

Chafing Chain:

• The Chafing chain is a stud link chain used for the standard connection between the strongpoint and a standard pear-shaped open link allowing connection to a standard bow shackle. 

• The chafing chain should be stowed in such a way that it can be rapidly connected to the strongpoint.

Towing Connection:

    The towing pennant should have a hard eye-formed termination allowing connection to the standard bow shackle.

Ready Availability of Towing Arrangements:

• To facilitate approval of such equipment and to ensure rapid deployment, emergency towing arrangements should comply with the following criteria:
  

• The pre-rigged emergency towing arrangement should be capable of being deployed in a controlled manner in harbour conditions in not more than 15 min.

• The pick-up gear for the pre-rigged towing pennant should be designed at least for manual operation by one person taking into account the absence of power and the potential for adverse environmental conditions that may prevail during such emergency towing operations.

• The pick-up gear should be protected against the weather and other adverse conditions that may prevail.

• The non-pre-rigged emergency towing arrangement should be capable of being deployed in harbour conditions in not more than 1 hour.
• The forward emergency towing arrangement should be designed at least with a means of securing a towline to the chafing gear using a suitably positioned pedestal roller to facilitate the connection of the towing pennant. 
• Pre-rigged emergency towing arrangements at both ends of the ship may be accepted.
• All emergency towing arrangements should be clearly marked to facilitate safe and effective use even in darkness and poor visibility.

• All emergency towing components should be inspected by ships personnel at regular intervals and maintained in good working orders.

Reference: IMO Publications & Documents - Resolution - Maritime Safety Committee - Resolution MSC.35(63)