Seismic Survey vessel “A” was conducting a marine seismic survey on a North Sea field. Vessel was towing ten seismic streamers at a speed of 4.5kts, each 6000m in length, separated by 100m, at a depth of 8 metres. Each streamer had tail buoy attached (bright yellow in colour and marked with yellow flashing light) to the end of the streamer. Vessel “A” was accompanied by chase and guard vessels “B” and “C”, the latter positioned behind the tail buoys, “C” proceeding ahead of the seismic vessel). Seismic vessel is restricted in ability to manoeuvre due to towed equipment. All correct lights and shapes displayed by all vessels on the seismic survey.
During morning of the incident at sunrise, a leisure yacht under sail, approximately 30-40′ in length flying Dutch flag was observed to be on a course which would result in her crossing behind the seismic vessel from starboard to port at a range of 4-5kilometres astern of the seismic vessel (thereby directly over the towed marine equipment and at high risk of being hit by the tail buoys). Multiple attempts were made to contact the vessel using VHF by all three vessels, however no persons were visible on deck, vessel appeared to be sailing with no lookout. No navigation lights were visible. Chase Vessel “C” was dispatched to intercept the yacht- they attempted to make contact using VHF, searchlight, ships whistle and then ultimately bullhorn. Contact was finally made when the yacht was approximately 150 metres away from the line of ten tallboys, having sailed over 5 of the ten towed streamers. Yacht then motored out of the danger area under direction of the chase vessel. Contact was established by shouting from vessel to vessel whereby the yacht indicated that they were bound for UK but had neither lookout nor functional VHF. Yacht crew (2 persons) had limited command of English, and vessel was not marked with name, hence it was not possible to establish the identity of the yacht.
Had the chase vessel been unable to reach and safely escort the yacht clear of the towed equipment, then the yacht had very high risk of being struck or entangled by tail buoy, which may have resulted in serious damage to the yacht.
Lessons Learned: Causes:
• Until becoming dangerously close, the seismic vessel did not spot the sailing yacht early enough, either visually or by radar, nor did the chase vessels assigned to the same. Radar settings not optimised for prevailing weather conditions.
• Sailing vessel visually obscured by wave height and sun low on horizon behind – Position of chase vessels could have been improved so as to assist with early detection and intervention.
• Yacht was not compliant with IRPCS or conducting any form of lookout. – Yacht did not carry operational VHF radio or any other auxiliary means of detection (AIS, radar reflector or similar).
• Project was not correctly notified on Navtex / NTM. -Lack of understanding of the potential hazards of offshore operations by leisure users.
We are pleased to publish reports that demonstrate the value of using root cause analysis after receiving a report of a hazardous occurrence.
We were advised the operator conducted a full incident investigation in cooperation with their client. Recommendations were issued to all vessels in their fleet, both in terms of positioning of guard vessels and the need for additional means of attracting the attention of uncooperative vessels (white parachute signal flares). They conducted a full review of their procedures along with those of their chartered chase vessel operators.
We hope the publication of this report will promote the need for a better understanding amongst leisure yachts as to the dangers of sailing through an oil field and the potential hazards in marine seismic operational areas.