Classification
| Field | Value |
|---|
| Incident Type | Grounded |
| Severity | High |
| Investigation Body | MAIB |
Vessel Details
| Field | Value |
|---|
| Vessel Name | ALP Forward |
| Vessel Names | ALP Forward; Transocean Winner |
| Vessel Type | Tug |
| Flag State | Netherlands [NL] |
| IMO Number | 9367516 |
| Gross Tonnage | 2789 |
| LOA (m) | 65 |
| Breadth (m) | |
| Other Involved Vessels | Transocean Winner, unmanned semi-submersible drilling rig |
Incident Details
| Field | Value |
|---|
| Date | 2016-08-08 |
| Region | United Kingdom |
| Location | Dalmore Bay, Isle of Lewis, Scotland |
| Coordinates | 58.2000, -8.0000 |
| Fatalities | 0 |
| Injuries | 0 |
| Missing | 0 |
| Direct Damage | |
| Economic Damage | |
Key facts
- ALP Forward departed Stavanger with Transocean Winner under tow on 5 August 2016.
- Weather deteriorated west of Scotland, increasing tow-line loading and reducing the tug's ability to control the rig.
- The tow stops were damaged and the main tow line failed; an emergency tow could not be established before the rig reached the coast.
- Transocean Winner grounded on the north coast of the Isle of Lewis at about 06:52 on 8 August.
- Damage to the rig's starboard pontoon released approximately 53 cubic metres of diesel.
Narrative
ALP Forward was towing the unmanned semi-submersible drilling rig Transocean Winner from Stavanger to Malta. The tug and tow departed on 5 August 2016 with a 760-metre tow line. As the convoy passed north of the Orkney Islands and west of the Flannan Isles, weather conditions deteriorated. Wind and sea forces increased the tension in the tow line and reduced ALP Forward's ability to control the rig. The tug's master manoeuvred to influence the tow's track and later shortened or adjusted the tow line as the convoy was driven toward the Isle of Lewis. At about 14:20 on 7 August, a gog chain broke during a manoeuvre. The tow line swept across the tug's main deck and damaged both tow stops. At 04:21 on 8 August, the tow line between the vessels failed. The crew recovered the remaining line and prepared an emergency tow, but the messenger could not be passed and the emergency connection was not established. At about 06:52, Transocean Winner grounded on the north coast of the Isle of Lewis in Dalmore Bay. The rig's starboard pontoon was damaged as it moved in the rough seas, releasing about 53 cubic metres of diesel. The MAIB concluded that tow-line loading, insufficient planning information and ineffective shoreside monitoring contributed to the loss of tow and subsequent grounding. Transocean Winner was unmanned, and no one on either vessel was injured or killed.
Sequence of events
| Date/time | Event |
|---|
| 2016-08-05 13:00 | ALP Forward and Transocean Winner departed Stavanger under tow. |
| 2016-08-07 14:20 | A gog chain broke during a manoeuvre; the tow line damaged both tow stops. |
| 2016-08-08 04:21 | The main tow line failed and the crew began preparing an emergency tow. |
| 2016-08-08 05:36 | ALP Forward reported that it could not establish the emergency tow. |
| 2016-08-08 06:52 | Transocean Winner grounded on the north coast of the Isle of Lewis. |
Contributing factors
| Factor | Evidence status | Description |
|---|
| Tow-line loading in deteriorating weather | Confirmed finding | Increasing wind and sea forces reduced ALP Forward's ability to control the tow and contributed to damage and failure in the towing arrangement. |
| Insufficient towage planning information | Confirmed finding | The MAIB found that the planning information available for the voyage was insufficient to assess and manage the developing risk. |
| Ineffective shoreside monitoring | Confirmed finding | Shoreside monitoring did not provide adequate support as the tow encountered worsening conditions and drifted toward the coast. |
Investigation
The Marine Accident Investigation Branch investigated the grounding in Report 19/2017. The report is centred on the grounding of Transocean Winner following the loss of tow from ALP Forward. It concluded that tow-line loading, insufficient planning information and ineffective shoreside monitoring contributed to the casualty. The report records damage to the tow stops, failure of the main tow line, damage to the rig's pontoon and release of about 53 cubic metres of diesel. It does not provide a simple monetary loss estimate.
References
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