Investigators said NPP had relied 'to some extent' on the 6m draft ferry Dieppe to help limit silting of the channel. However, at the time of the grounding the ship had not been in the port for almost a month as it was undergoing a refit.

In the week before the grounding, bad weather caused a significant increase in silting, and accurate depths in the approaches had not been determined because of defective surveying equipment.

'No control measures were implemented to mitigate the risk of unknown depth, save that the master attempted to navigate in what he assessed to be the deeper side of the channel,' the report states.

The report accuses NPP of failing to take the measures required by the Port Marine Safety Code in respect of the control and monitoring of the channel depth and of the operating restrictions imposed on Transmanche Ferries.