So, regarding the ferries being built at Ferguson's [bear with me]…diesel generator charges batteries which in turn power electric motors that turn the propeller. This is exciting stuff, but there surely must be concerns about removing the physical link between physical motor and engine? Should the hybrid ferry fall victim to an extra-ordinary electrical fault, would the diesel generators have enough capacity to directly drive the motors? If this isn’t possible, then surely having no direct propulsion or backup system in place represents a significant obstacle in terms of safety? I’m also mindful of the current – no pun intended – design on large cruise liners with these Azipod electric motors powered by diesel-electric motors, but the key difference there is that the diesels are on continuously, so perhaps that’s your angle?! Would love to know more.

I’m in no way affiliated in anything and this is purely to satisfy my own curiosity! I wholeheartedly wish all the staff at Ferguson’s the best of luck in this and hopefully more orders will come to the Clyde.

John H

Hi John, I have no link whatsoever to the design or building of these ferries. I'm just very much interested in this kind of thing and shipbuilding in general. I wish I'd done an apprenticeship in welding, fabrication, or engineering when I left school... maybe my day will happen though.

I would imagine there is no reason that the engines can't supply enough power to drive the motors directly if required. Consider this: if the batteries are running low, and the engines need to come on to charge the batteries, the generators need to be able to power the ship AND charge the batteries, otherwise, the batteries will still run out, just run out slower than before the engines come on. Basically, the generators will have to be capable of generating AT LEAST enough energy to run the motors, any extra then goes to charge the batteries.

I would imagine the ship could run all day every day on the generators, but the beauty of the batteries is they don't have to. The ferries can be charged over night, and may be enough to drive them all day on a calm day like it’s been today, no wind, no waves, on battery power alone. However, given the rough seas we get, the charge may not last the whole day; this is where the generators come in.

Regarding the concerns about not having a physical link between generator/engine and propeller, or some sort of electric fault, it is still possible for any engine to suffer engine electric failure, resulting in a breakdown, even on a shaft driven prop. Thankfully, ship electric systems are designed by some of the most knowledgeable top level electrical engineers, and I shouldn't think they would do it if there was any doubt on its safety.

Again, I'm no engineer, and I have no hand in designing or building the ship (although I would love to be involved in building. fingers crossed!)

Blake

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