The new Stornoway ferry is specially designed to have next to none disruptions due to mechanical breakdowns.
Three back-up engines aim to keep the ship going on her regular timetable and speed even if one of her two main engines breaks down.
Such a set-up is a huge advantage over the present MV Isle of Lewis which cannot legally sail unless it has two fully operating main engines.
Any one of the MV Loch Seaforth’s three generators - normally used for making electricity for onboard use - can be used to drive a propeller through a propulsion unit and separate input into the gearboxes.
This bypass system satisfies strict UK maritime safety rules and may also be used to stop an engine for regular maintenance at sea or even to allow for cleaning or painting.
However, only one propulsion unit can be run at any time so at least one main engine has to be running normally.
Caledonian Maritime Assets Limited (CMAL), which will lease the vessel to the ferry operator said that the ship can reach about 15 knots with just one main engine.
Firing up one of the propulsion units can add at least another four knots taking her to full speed.
A CMAL spokesman said: “In reality CMAL thinks it would be more likely that the power to both propellers would be equalised to give the normal service speed.
“There is a lot of reserve power in the engines and the service speed can easily be reached.”
Loch Seaforth specifications:
2 main engines rated at 4000kW each
3 generator engines rated at 1600kW each
1 auxiliary generator engine rated at 700kW
1 emergency generator engine rated at 700kW
2 main propeller absorbing 4000kW power
1 stern thruster rated at 900kW
2 bow thrusters rated at 900kW each
2 propeller drive motors rated at 3500kW
The main engines, generators, propellers and thrusters can be used at full power all together, though this unlikely to ever be necessary
►Building of the new Stornoway ferry is underway
