Roughly 21% of the Ben-my-Chree’s journey from Douglas to Heysham would be affected by its current energy efficiency limitations.

This is according to the Treasury Minister Dr Alex Allinson, who confirmed in response to a written question that only 12 of the 56 miles in the journey would be subjected to the lesser power.

The vessel was due to stand in for the Manxman on four separate days between March and May while the Manxman underwent servicing of its Marine Evacuation System, but the Manannan fast-craft took on the first sailing because of the Ben-my-Chree’s unavailability.

It is currently unclear whether the Ben-my-Chree will take on the other three sailings on April 15, April 25 and May 7.

If it does, it will only able to travel at 14 to 15 knots rather than the normal 18 knots because of new energy efficiency restrictions.

Amendments were made to the ‘International Convention for the Prevention of Pollution from Ships’, also known as ‘MARPOL’, which required ships to improve their energy efficiency in the short term and thereby reduce their greenhouse gas emissions.

In response to the written question from Douglas Central MHK Chris Thomas about how long journeys would take under these restrictions, Dr Allinson replied: ‘From January 1, 2023, it became compulsory for all vessels to calculate their energy efficiency levels.

‘The Ben-my-Chree has been issued with a short term “International Air Pollution Prevention” (IAPP) certificate by its classification society.

‘Both “coastal states”, the Isle of Man Ship Registry (IoMSR) and UK Maritime and Coastguard Agency (UKMCA) issued waivers to allow IoMSPC to operate without the power limitation (i.e. use of 100% engine power) within their respective waters. ‘IoMSR allowed this for manoeuvring in port and the UKMCA allowed it for manoeuvring and passage.

‘Therefore, the only time the limitation would have been applied would be for around 12 miles of the journey to depart or arrive in IOM waters. The remaining 44 miles would be at full power and speed.

‘As power speed curves for all vessels are exponential, it is estimated that the Ben-my-Chree would operate at 83% speed using 50% power. At 100% power her service speed is 18 knots, therefore at 50% power her speed would be estimated to be 15 knots.

‘This translates as an estimate to 12 miles at 15 knots, plus 44 miles at 18 knots, plus manoeuvring at either port, to a 3 hours and 50 minutes journey.’