Classification
- Incident Type: Other
- Severity: High
Vessel Details
| Field | Value |
|---|---|
| Vessel Name | Cougar Ace |
| Vessel Type | Ro-Ro / Car Carrier |
| Flag State | Singapore [SG] |
| IMO Number | 9051375 |
| Gross Tonnage | 55328 |
| LOA (m) | 199.34 |
| Owner/Operator | Mitsui O.S.K. Lines |
| Year Built | 1993 |
| Persons on Board | 23 |
| Cargo | Approximately 4,813 vehicles |
Incident Details
| Field | Value |
|---|---|
| Date | 2006-07-24 |
| Location | North Pacific, south of the Aleutian Islands; initial position 48 deg 14' N, 174 deg 26' W |
| Coordinates | 48.233333, -174.433333 |
| Region | Pacific Ocean |
| Fatalities | 0 |
| Injuries | 1 |
| Missing | 0 |
| Vessels Lost | 0 |
| Environmental Impact | ADEC reported a small lubricating-oil sheen at the bow-thruster area and an undetermined amount of lubricant and transmission fluid on cargo decks. |
| Outcome | All 23 crew were rescued; Cougar Ace remained afloat, was moored in Wide Bay during salvage, and was later towed for cargo discharge and repairs. |
Key facts
- Cougar Ace developed a severe port list during ballast-water adjustment south of the Aleutian Islands on 24 July 2006.
- All 23 crewmembers were rescued; Mitsui O.S.K. Lines reported that one crewmember injured a leg.
- The operator reported that excessive discharge from bottom ballast tanks caused instability during ballast adjustment, but this was not a formal investigation finding.
- The vessel remained afloat and was towed to Wide Bay, Unalaska Island, where it was moored while salvage crews worked to restore its stability.
- Cougar Ace carried approximately 4,813 vehicles, according to the Alaska Department of Environmental Conservation.
Narrative
On 24 July 2006, the Singapore-flagged car carrier Cougar Ace was in the North Pacific south of the Aleutian Islands when it developed a severe list to port during ballast-water adjustment. Mitsui O.S.K. Lines gave the initial position as 48 degrees 14 minutes north, 174 degrees 26 minutes west. The vessel became not under command and required an emergency response.
U.S. Coast Guard and Alaska Air National Guard helicopters evacuated all 23 crewmembers. The operator reported that one crewmember injured a leg. No crew fatalities or missing persons were reported. The Alaska Department of Environmental Conservation monitored the vessel and the salvage response, including pollution risks associated with the ship's fuel and cargo. Cougar Ace remained afloat despite the extreme list.
MOL's 28 July update presented an operator assessment of the probable cause. It stated that the vessel became unstable during ballast-water adjustment after too much seawater was discharged from bottom ballast tanks. According to that account, the vessel rolled on a swell and suddenly listed while the ballast operation was in progress. No formal marine casualty investigation report is identified in the reviewed web sources, so this explanation is treated as operator-reported rather than as an official finding.
Salvage and towing preparations continued after the crew evacuation. The tug Emma Foss took the vessel in tow on 31 July, and the tug Sea Victory later assisted with the movement toward Dutch Harbor. On 8 August, attending tugs secured Cougar Ace to mooring buoys in Wide Bay, Unalaska, while salvage crews worked to restore its stability. ADEC later reported that dewatering was completed and that the vessel was towed to Portland for cargo discharge and repairs. The reviewed sources establish that the vessel was not lost, but they do not provide a verified total for direct vessel damage or the overall economic loss.
Sequence of events
| Date/time | Event |
|---|---|
| 2006-07-24 | Cougar Ace developed a severe port list during ballast-water adjustment south of the Aleutian Islands. |
| 2006-07-24 | U.S. Coast Guard and Alaska Air National Guard helicopters rescued all 23 crewmembers. |
| 2006-07-28 | MOL reported its operator assessment that excessive discharge from bottom ballast tanks caused instability during ballast adjustment. |
| 2006-07-31 | The tug Emma Foss took Cougar Ace in tow toward the Bering Sea. |
| 2006-08-08 | Attending tugs secured Cougar Ace to mooring buoys in Wide Bay, Unalaska, for continued salvage work. |
| 2006-08-31 | ADEC reported that dewatering was complete and the vessel was later towed toward Portland for cargo discharge and repairs. |
Contributing factors
| Factor | Evidence status | Description |
|---|---|---|
| Ballast-water adjustment | Reported | MOL reported that instability developed while the vessel's ballast was being adjusted. |
| Excessive ballast discharge | Reported | The operator stated that too much seawater had been discharged from bottom ballast tanks. This is not presented as an official investigation finding. |
Investigation
The reviewed web evidence includes an official Alaska Department of Environmental Conservation response summary and situation reports, together with contemporaneous operator statements. No formal marine casualty investigation report is identified in those sources. MOL described excessive discharge from bottom ballast tanks during ballast adjustment as the probable cause. That statement is an operator account, not an official investigation finding. ADEC separately stated that the cause of the reported bow-thruster sheen had not been determined.
References
- Alaska Department of Environmental Conservation: M/V Cougar Ace
- Alaska Department of Environmental Conservation: Cougar Ace situation report 7
- Alaska Department of Environmental Conservation: FY08 biennial report, Cougar Ace response
- Mitsui O.S.K. Lines: Incident With The Car Carrier Cougar Ace
- Mitsui O.S.K. Lines: Incident with The Car Carrier Cougar Ace (No.3)
- Mitsui O.S.K. Lines: Incident with The Car Carrier Cougar Ace (No.4)