The ShipArrestor: Stopping ships drifting to disaster

Norwegian company Miko Marine will display its ShipArrestor system at the upcoming European Innovation Convention in Brussels. One of fifty chosen innovative projects and partly funded by the European Union, the ShipArrestor has been developed by a consortium of eight European organisations. The project group included setups from France, Germany, Netherlands, Norway, the UK and Austria; each organisation brought specific expertise to the project, and Miko Marine now says that a practical and cost effective defence against the environmental and commercial dangers of grounding of ships has been successfully tested.

The system involves a helicopter approaching the forecastle of a disabled vessel even after it has been abandoned, and attaching a towline to the ship. A specially outfitted helicopter is not required; a conventional SAR helicopter can deploy the line around the winch gear on the forecastle of an abandoned vessel. The helicopter then lays the line upwind and releases it. The towline ends in a sea anchor that reduces the drift of the ship by up to 50%, giving a rescue tug double the time to reach the disabled vessel- critical time is thus bought in cases where the vessel is close to danger, and control over the ship is regained. 

Milo says that extensive tests have shown excellent results. In one trial, a 30m diameter nylon sea anchor was able to turn a 120,000-ton LNG carrier vessel into the wind and slow its drift by 58%.  Obviously, the benefits will be enormous for the ship, crew, cargo and the environment if such results can be replicated in real life situations. 

Moreover, with cost cutting measures in the UK and elsewhere affecting emergency response capabilities, (as an example, the UK's four Emergency Towing Vessels have recently had their funding withdrawn) the ShipArrestor is being promoted by Miko as a solution that would enable fewer rescue tugs to service the same area at much lower cost.

Challenges in development of the hardware for the project were many. Mathematical modelling was used to zero in the size of sea anchors that needed to be used for a wide variety of tonnages and types of vessels, keeping in mind the towline and the sea anchor had to be light enough to be carried aboard a conventional SAR helicopter. In addition, the towline had to be strong, light and especially abrasion resistant, the last because it would chaff over the gunwale of the disabled vessel. Eventually, a new chain was developed for use, offering excellent performance at half the weight of conventional material. 

A vessel drifting close to danger must ideally be slowed down and turned against the weather. A towing point must be fixed quickly and the towing commenced before she runs aground.  Miko says its system will rotate the bow of even large cargo vessels against the weather and reduce their drift rate, increasing salvage chances. "The combination of a sea-anchor (with diameter up to 40 meters), the synthetic fibre towing line and the pick-up buoy solution provides the salvor more time and when in place, a fast and secure way to connect and start the tow", it says, adding that the sea anchor may be used as a stand alone product if needed. Alternately, "the tow-line and sea-anchor combination attached to a pick-up buoy will allow the salvor to start towing the casualty into a safe haven", Miko says.

Miko Marine sees a possibility that its sea anchor could be carried permanently aboard vessels for emergency deployment in future. Maritime authorities in European nations like Sweden and Norway are already considering the ShipArrestor for the protection of their coastlines, reports indicate.