| Abeam | Position or direction which lies horizontally at right angles to the vessel's fore and aft line |
| AHTS | Anchor handling/tug/supply vessels |
| Anchor Cables | Chains for attaching the anchors to the vessel |
| Bar | A unit of pressure which is 105 N/m2, equivalent to 14.5 lb/in2 |
| Bollard Pull | The maximum pulling, or pushing, power of a tug |
| Bow Thruster | An independently powered propeller fitted in a transverse tunnel in the bows of the vessel to improve the handling characteristics during manoeuvring |
| Bulkhead | A vertical partition in the vessel which is often watertight |
| Cable | Unit of distance equalling 1/10th of a nautical mile (608 ft/185 metres) |
| CHA | Competent Harbour Authority |
| Course Made Good | The actual track of the vessel |
| DNV | Det Norske Veritas |
| Draught | Distance from the waterline to the bottom of the vessel when the vessel is afloat |
| dwt | Deadweight tonnes which is the carrying capacity of the vessel |
| ETA | Estimated time of arrival |
| Frame | A continuous structure supporting the sides, bottom and deck plating of the vessel |
| Gyro | A type of compass |
| Hawse Pipes | Tubes built into the vessel's bows through which the anchor cables run |
| IMO | International Maritime Organization |
| Inert Gas | A gas with an oxygen content of less than 8% which does not support combustion and is pumped into the ullage space above oil cargoes |
| Knots | Nautical miles per hour |
| Leading Lights | Two or more lights which identify a line of safe approach when they are in line |
| Lee | Downwind side of the vessel |
| List | Transverse inclination of the vessel caused by unsymmetrical distribution of weights |
| Local Commander | The senior MPCU official in attendance at the scene of the incident |
| LOF | Lloyd's Standard Form of Salvage Agreement |
| MARPOL | International Convention for the Prevention of Pollution from Ships 1973/78 |
| MEOR | Marine Emergency Operations Room (situated in The Coastguard Agency headquarters at Southampton) |
| Merchant Shipping | Notices issued by the Department of Transport to the
Notices (M Notices) Shipping Industry, identified by the letter M and a number |
| MHPA | Milford Haven Port Authority |
| Mile | Nautical mile, about 1.15 statute miles |
| MoD | Ministry of Defence |
| MPCU | Marine Pollution Control Unit of The Coastguard Agency |
| MPSC | Marine Pollution Salvage Centre which holds MPCU's stockpile of pollution control and clean-up equipment. |
| MRC | Marine Response Centre located at Milford Haven Coastguard Station during the duration of the incident |
| MRCC | Marine Rescue Co-ordination Centre of HM Coastguard |
| MRSC | Marine Rescue Sub-Centre of HM Coastguard |
| MSA | Marine Safety Agency of the Department of Transport |
| Overall Commander | The senior Coastguard Agency officer who co-ordinates the efforts of HM Coastguard, MPCU and other organisations involved in dealing with the emergency |
| P & I | Protection and Indemnity Association |
| Pressure/Vacuum Valves | A device fitted at the top of a cargo tank to prevent either an over-pressurisation or a vacuum forming within the tank |
| RNLI | Royal National Lifeboat Institution |
| SERS | Lloyd's Register of Shipping, Ship Emergency Response Service |
| Shackle | Length of anchor chain equivalent to 15 fathoms (90ft/27 metres) |
| Speed Made Good | Average speed of the vessel |
| Squat | An increase of the vessel's draught caused by her movement through the water |
| tbp | Tonnes bollard pull |
| Trim | Difference between the forward and after draughts of the vessel when afloat. The vessel is trimmed by the head when the forward draught is greater than the after draught |
| Ullage | The measurement between the top of the tank and the surface of liquid in the tank |
| VHF | Radios using Very High Frequency which have designated marine channels |
| VLCC | Very large crude carrier (greater than 200,000 dwt) |
| VTS | Vessel Traffic Services for handling shipping movements within harbour limits |
| Weigh anchor | To lift the anchor from the seabed |
| Windlass | Machinery for deploying or recovering the anchors |
The vessel is constructed with some side ballast tanks but no double bottom tanks. The starboard side cargo and ballast tanks were ruptured when the vessel first grounded resulting in a heavy trim by the head and a starboard list. A quantity of oil was released from the damaged cargo tanks.
Both the Milford Haven Port Authority's Emergency Plan and the Marine Pollution Control Unit's National Contingency Plan were implemented promptly. Within hours the managers of SEA EMPRESS had accepted an offer of assistance from a salvage consortium on the terms of Lloyd's Standard Form of Salvage Agreement, "No Cure - No Pay" (LOF95).
SEA EMPRESS was manoeuvred into deeper water where she could be anchored and held in position with the aid of the harbour tugs from Milford Haven. This was achieved without further loss of cargo and the intention was to lighten the casualty as soon as possible so as to allow her to enter the Haven and discharge the remainder of her cargo. A suitable lightening vessel was identified and preparations were commenced to ready SEA EMPRESS for this operation.
The prediction of gale force winds led to the decision to turn the casualty and re-anchor her so that she would be heading into the wind. This operation was carried out on 17 February while the preparations for lightening were still underway. It was just after this turning operation, and when the weather conditions had already deteriorated, that control of the casualty was lost and she grounded off Saint Ann's Head.
For the next four days efforts by the salvors to regain control of the casualty were unsuccessful and the casualty went aground again on a number of occasions, both off Middle Channel Rocks and Saint Ann's Head. It was not until 21 February that the casualty was successfully refloated and brought under control. She was then taken to a berth inside the Haven where the remainder of her cargo was discharged.
There was no loss of life or serious injuries.
The cause of the initial grounding has been found to be due to pilot error.
The main factors, apart from the bad weather, which resulted in the salvage operation taking so long, were insufficient tugs of the appropriate power and manoeuvrability, together with a lack of full understanding of the tidal currents in the area.
The initial grounding resulted in approximately 2,500 tonnes of crude oil escaping and about a further 69,300 tonnes was lost to the sea during the period of the salvage operation.
A number of recommendations have been made, which are addressed to Milford Haven Port Authority, the Department of Transport/Marine Safety Agency, The Coastguard Agency and Acomarit (UK) Ltd.
