A sea-going tug was towing a hulk of the UK coast, when the towed vessel developed a list of about 10° to port. The tug’s master called the coastguard to request permission to seek shelter in a local bay so that the list could be investigated. This was granted and he altered course for the bay, reducing the scope of his tow as he went.
Once in the shelter of the bay, the master put the tug alongside the towed vessel, stem to stern. However, safe access to it was not possible, so he proceeded further into the bay with the intention of anchoring and taking the tug’s rescue craft over to the towed vessel. The tidal stream in the bay was about 0.9kt, it was dark, but visibility was good with light winds and slight seas.
Once clear of his tow, the master drifted for some time before ordering the anchor to be dropped. Satisfied that he was secure, he started to use the tug’s searchlight to find the towed vessel, only to see it bearing down on the tug. He immediately took evasive action using the tug’s engines and bow thruster, but was unable to avoid the towed vessel, which struck and holed the tug just aft of midships. The damage was below the waterline and in
way of the engine room.
The master immediately raised the alarm and attempted to run the tug aground to avoid sinking. With significant assistance the tug was saved but, several hours after the collision, the towed vessel sank. The tug’s master was not familiar with operating in tidal waters and had inadvertently anchored down-tide of the towed vessel, leading to the collision.