The Ben-my-Chree is currently having to operate at 48% of its usual power due to energy efficiency restrictions.

The vessel, which is set to replace the Manxman on four different days between March and May due to servicing works on the flagship, will only able to travel at 14 to 15 knots rather than the normal 18 knots because of new restrictions.

It comes after amendments were made to the ‘International Convention for the Prevention of Pollution from Ships’, also known as ‘MARPOL’.

These amendments require ships to improve their energy efficiency in the short term and thereby reduce their greenhouse gas emissions.

Speaking about the issue during Tuesday’s House of Keys sitting, Treasury Minister Dr Alex Allinson said: ‘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.

‘The classification society undertook a preliminary calculation, which estimated that in order to comply with energy efficiency regulations, the Ben-my-Chree would need to be limited to 48% of its engines “maximum continuous rating” (MCR).

‘Therefore, the short term IAPP certificate has been issued on the basis that the vessel manually complies with this preliminary limitation, which includes the reduction of speed from 18 knots to 14 or 15 knots.’

Dr Allinson said the initial calculation from the classification society used some inaccurate figures, meaning that the final calculations are likely to be more favourable to the vessel. He said: ‘The Ben-my-Chree might still need some permanent efficiency improvements to meet the required standard.

‘The Steam Packet Company will require an extension of the short term IAPP certificate so that the recalculation of the ships energy efficiency can be completed.’

This means that the Ben my Chree is required to run at 48% of its usual power until the recalculation. A constituent of Dr Allinson’s, who is a retired sea merchant, calculated that a 48% level of power for the Ben my Chree should mean that journeys will have a further 36 to 48 minutes than usual. Meanwhile, the Isle of Man Ship Registry has permitted the Ben-my-Chree to break its current power limitation while berthing in Douglas Harbour, due to the fact that it can be challenging to manoeuvre the vessel on lower power.

On how long the vessel would have to operate at 48% power, Dr Allinson said: ‘I assume the extension to the current temporary IAPP certificate will take place on a month to month basis until the energy emissions are properly calculated.

‘This issue should be resolved relatively quickly once a correct recalculation has been made.’

Dr Allinson confirmed that the Manxman and Manannan are not required to meet energy efficiency regulations as both have ‘unconventional propulsion systems’.