Emergency Towing Arrangement

What sets an emergency towing arrangement apart

When a large ship loses power in heavy weather near a coast, the time between the failure and a grounding can be short. A rescue tug arriving at the scene needs a safe, strong connection point it can reach quickly, with a towline that can be passed without a long operation on a pitching deck. The emergency towing arrangement, usually shortened to ETA, provides exactly that. It is a complete set of equipment on the bow and the stern, built so that it can be released or rigged by a small crew, and without main power. It is installed to be ready, not to be used often, and its readiness has to be proven by regular checks.

Main components

• Strongpoint or chain stopper, the fitting that takes the towing load and passes it into the hull structure
• Fairlead, a guide that leads the towing line over the ship's side without sharp bends
• Towing pennant or chain, designed to carry the tow and attached to the strongpoint
• Chafing gear that protects the pennant against wear at the fairlead
• Pick-up gear with a floating line and a messenger, so the tug can recover the pennant from the water
• Release and securing devices, such as lashings, holders or a quick-release mechanism, that keep the equipment stowed until it is needed

Main designs

• Forward arrangements, where the towing pennant is stowed at the bow and can be rigged and deployed by a limited crew
• Aft arrangements, which are normally pre-rigged so that they can be deployed quickly by a small crew
• Combined strongpoint and chain stopper assemblies, in versions that fit different deck layouts
• Equipment variants sized to ship classes, with different working load capacities and chain dimensions

Selection and sizing

• Working load and breaking load matched to the ship's size class, as specified in the guidelines
• Location and structural support, so the strongpoint transmits the load into reinforced hull structure
• Pennant and chain dimensions that fit the strongpoint, the fairlead and the available storage
• Pick-up gear arranged for the shape of the ship and the likely sea conditions at the time of use
• Marking, signage and instructions that can be understood by a stressed crew
• Arrangement of the securing devices so the equipment cannot move in heavy seas but can be released quickly

Regulations and class

SOLAS requires emergency towing arrangements on tankers above a defined deadweight, fitted at both ends, with technical requirements set out in an IMO guideline on emergency towing arrangements for tankers. The equipment must be approved by the flag state or the classification society, and the approval covers the combination of strongpoint, fairlead and associated gear. Installation drawings, strength calculations and test records have to be available, and the equipment is checked at surveys and during ship inspections.

Typical faults

• Corrosion and seized parts on the strongpoint, the chain stopper pawl or the fairlead after years without use
• Deteriorated lashings, lines or quick-release devices, which can fail when needed
• Pennant, chain or pick-up line out of date or damaged by chafing or sunlight
• Equipment moved, blocked or covered by other deck fittings or stores, so it cannot be reached quickly
• Missing or faded signage and instructions, particularly on older vessels
• Crew unfamiliarity, because the system is rarely trained and the people who know it have left the ship

What to look for in a supplier

• A type-approval certificate that names the exact strongpoint, fairlead and pennant combination
• Strength documentation that matches the ship's size class and the hull reinforcement
• Complete sets including pick-up gear, chafing gear and securing devices
• Replacement pennants, lines and lashings available as separate items
• Installation drawings and training material for the crew

Include the emergency towing arrangement in the regular deck rounds and drill it with the crew, not only on paper. Equipment that has never been moved is the equipment most likely to be seized.