An investigation into the grounding of a tanker off the South West coast has blamed poor watchkeeping and bad use of navigational aids.

The 3,000-tonne German vessel, the MV Willy, caused a major alert when it went onto rocks in Cawsand Bay, near Plymouth Sound, in stormy weather on 1 January.

About 150 people from Cawsand village were moved from their homes amid fears fumes could explode, after fuel the ship was carrying leaked.

The Marine Accident Investigation Branch has made several recommendations to ship owners, including optimising watchkeeping practices and navigation aids.

The ship was refloated and towed off

The 1981-built vessel had already discharged most of its cargo at Plymouth's Cattedown docks.

But it was still carrying 93 tonnes of intermediate fuel oil, 41 tonnes of gas oil and fives tonnes of lubricating oil.

The vessel ran aground in the Plymouth Sound and Estuaries Special Area of Conservation and Special Protection Area.

After the vessel was grounded, fuel formed a film on the sea 1km long and a major rescue operation was launched.

The operation involved coastguards, the RAF and the Queen's Harbour Master. The crew was led to safety from the stricken vessel.

The fuel tanks were filled with compressed air to force water out of the bottom of the vessel.

It was successfully refloated after 11 days and then taken to Falmouth.

Amongst the reasons being blamed for the grounding were the strong south-easterly winds and swell.

Engine failure

But as well as the weather, the report also said: "The amount of cable used for the anchor was insufficient given the weather conditions, depth of water, nature of the seabed and condition of the ship."

The ship's movement was not detected properly by the Officer of the Watch, and the global positioning system was wrongly set.

The report also said: "The master was not informed of the situation until seven minutes after the anchor had started to drag."

The ship's engine also could not be started and made available in sufficient time to allow the ship to be moved clear of danger.

The tanker has since been scrapped.