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The Ferry Man

CONDOR FERRIES: Condor Liberation

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I suppose there is the possibility Condor Lib could have sucked in something stirred up by the work on South Quay but I thought the harbour bed at the berth had been armoured with Purbeck stone against the scour produced by waterjet thrust.  Personally I'd guess the cause is something else.  It could even be a design defect so Condor would then need to take up the matter with the builders and the manufacturers of the waterjets.

 

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16 hours ago, Cabin-boy said:

They are situated on top of the water jets in normal use and swing down to redirect the flow back towards the bow when reversing.

Take a look at this and in particular the images on the right hand side.

https://en.wikipedia.org/wiki/Pump-jet

Ed

Ed, Lib's Wartsila jets don't invert, they have  rear mounted reverse plate & Jetavator:

 

The jet stream is deflected by a jetavator which is mounted behind the stator bowl. The jetavator is actuated by two hydraulic cylinders. The jetavator can be deflected 30° to port and 30° to starboard. The jetavator contains a hydraulically activated reverse plate through which part or all of the jet stream can be deflected forward. The reverse plate can be gradually moved, which makes it possible to vary the thrust from full ahead via the zero thrust position to full astern vice versa. The reverse plate must be in the zero thrust position before the waterjet shaft is clutched in. The zero thrust position prevents the ship from moving when the waterjet pump starts giving a flow. The reverse cylinder is equipped with an over-center valve (load holding valve). This safety device prevents that, in the event of a hose failure, the reverse plate moves to full astern without control. Steering and reversing are activated by the control system. The position of the jetavator and the position of the reversing plate are fed back to the control system. These positions are measured by sensors inside the hydraulic cylinders. 

modular-waterjets-principle-1.png

modular-waterjets-principle-3.png

Edited by jonno

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5 hours ago, jonno said:

Ed, Lib's Wartsila jets don't invert, they have  rear mounted reverse plate & Jetavator:

 

The jet stream is deflected by a jetavator which is mounted behind the stator bowl. The jetavator is actuated by two hydraulic cylinders. The jetavator can be deflected 30° to port and 30° to starboard. The jetavator contains a hydraulically activated reverse plate through which part or all of the jet stream can be deflected forward. The reverse plate can be gradually moved, which makes it possible to vary the thrust from full ahead via the zero thrust position to full astern vice versa. The reverse plate must be in the zero thrust position before the waterjet shaft is clutched in. The zero thrust position prevents the ship from moving when the waterjet pump starts giving a flow. The reverse cylinder is equipped with an over-center valve (load holding valve). This safety device prevents that, in the event of a hose failure, the reverse plate moves to full astern without control. Steering and reversing are activated by the control system. The position of the jetavator and the position of the reversing plate are fed back to the control system. These positions are measured by sensors inside the hydraulic cylinders. 

modular-waterjets-principle-1.png

modular-waterjets-principle-3.png

Very interesting -- but I don't see a component called a "bucket" unless in this design of waterjet it is called a "jetavator".  I wonder what's gone wrong with them on Condor Lib so that the crew was unaware of the defects and consequently they had to be detected during the course of a routine diving inspection.

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Thanks Jonno. So as HT says, is the bucket referred to by Condor's press release just a simplified word for the more complex arrangement you detailed above?  Ed. 

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The less sophisticated or smaller hydrojet tend to have a bucket shaped deflector which is positioned in the output jet to reverse. 

http://www.castoldijet.it/en/waterjet_en/15638_en.html

 

Brings back memories of when I worked as a fisherman in the bay of St Brieuc. One of the amphibious barges I worked on had a jet which didn't have a clutch so the neutral was achieved by setting the bucket in its mid position to divide the flow equally between forward and reverse. I also remember being told that the hydrojet were better than propellers in shallow waters for high powered vessels notably because it offers a much reduced draught. The hydrojet are also less vulnerable to entanglement (nets, ropes) than a propeller and rudder arrangement. 

Edited by crechbleiz
Missing word
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HT, she doesn't have buckets...The only area I believe Condor can describe as any form of bucket is between the reverse plate and what Wartsila call the Jetavator but it's more like a short tunnel and substantial damage would occur way before any mechanism which is visible is reached, the inner seals and impellor would suffer major damage first. Remember the jet stream flows from inboard to outboard, the visible bit at the stern is principally similar to exhaust used against a greater solid mass to create thrust.

They've been designed specifically to alleviate foreign object damage especially in shallow water which is why the US Navy have opted for them on their Austel's and Libby deffo has Wartsila 1300,s fitted. 

I wonder whether it's the seawater intake mesh gates under the hull which are damaged hence the need for divers as older designs which may have a 'bucket' due to inverted thrust can be inspected visually without getting your feet wet.

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Jonno, I just can't imagine why Condor did not use the correct word Jetavator in their press release!  What do they take the travelling public for, fools?! 😁

I feel equally misled when cancellation of sailings is attributed to that rather vague and unsatisfactory term, "weather".  I mean, why can't they be straight and inform customers that the issue on the day is "a significant wave height 10% in excess of certification limit".  Or that "south-easterly severe gales are creating lee-shore conditions and dangerous breaking waves in the entrance to the Swash Channel".  Etc.

It would make all the difference to Keith and Edith from Little Barking to be properly informed of the real reason why they had to change their travel plans! 😀

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3 hours ago, Gareth said:

Jonno, I just can't imagine why Condor did not use the correct word Jetavator in their press release!  What do they take the travelling public for, fools?! 😁

I feel equally misled when cancellation of sailings is attributed to that rather vague and unsatisfactory term, "weather".  I mean, why can't they be straight and inform customers that the issue on the day is "a significant wave height 10% in excess of certification limit".  Or that "south-easterly severe gales are creating lee-shore conditions and dangerous breaking waves in the entrance to the Swash Channel".  Etc.

It would make all the difference to Keith and Edith from Little Barking to be properly informed of the real reason why they had to change their travel plans.

I'm not sure Joe the Travelling Public appreciates explanations that are too technical as they may not understand them, e.g. "What's the Swash Channel?"

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4 hours ago, Gareth said:

Jonno, I just can't imagine why Condor did not use the correct word Jetavator in their press release!  What do they take the travelling public for, fools?! 😁

I feel equally misled when cancellation of sailings is attributed to that rather vague and unsatisfactory term, "weather".  I mean, why can't they be straight and inform customers that the issue on the day is "a significant wave height 10% in excess of certification limit".  Or that "south-easterly severe gales are creating lee-shore conditions and dangerous breaking waves in the entrance to the Swash Channel".  Etc.

It would make all the difference to Keith and Edith from Little Barking to be properly informed of the real reason why they had to change their travel plans! 😀

Working on the railway, welcome to every single day at work :D:D

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4 hours ago, Gareth said:

Jonno, I just can't imagine why Condor did not use the correct word Jetavator in their press release!  What do they take the travelling public for, fools?! 😁

I feel equally misled when cancellation of sailings is attributed to that rather vague and unsatisfactory term, "weather".  I mean, why can't they be straight and inform customers that the issue on the day is "a significant wave height 10% in excess of certification limit".  Or that "south-easterly severe gales are creating lee-shore conditions and dangerous breaking waves in the entrance to the Swash Channel".  Etc.

It would make all the difference to Keith and Edith from Little Barking to be properly informed of the real reason why they had to change their travel plans! 😀

I understand your point Gareth and yes I know I can... or more probably do, get pedantic about such things but when I read a statement I know is just plain wrong the juices begin to flow.

LIbby doesn't have buckets or anything which could be perceived as such whether described in simple terms or not. Even a layman standing on the quayside can see the visual differences... This is a waterjet with a bucket.

WATERJET-FEATURES1.thumb.jpg.1eed60354980a6855501370d0fc7e806.jpg59f46d7fcf9bf_bucket2.jpg.5e250f5ad2a8eb5a3544865c2b1b82d4.jpg

 

 

A presser stating engine failure would have sufficed rather than seek to explain that damage occurred to a component that doesn't exist.

Would you accept a BF statement which indicated scrubber damage on Bretagne as the cause of sailing disruption when you know she doesn't have them fitted? 

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I must say how civilised this discussion is, it is how it should be, very interesting discussion now.   Much better discussing the problems in an adult manner than the fire and brimstone in other places.  I am finding the discussion about the waterjet systems quite enlightening.  Much better than umbrage at Libby’s shortcomings!  Much easier to discuss here.

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It's worth noting there is more than one make of waterjet and doubtless each manufacturer's product does differ technically.  I don't know what make was installed in Condor Lib and indeed what particular example from the manufacturer's range.  Doubtless the size of the HSC is an important factor affecting the decision what waterjet to install.  Again in some HSCs with four waterjets only two of the four are directional, the other two being for just forward thrust and thus don't need buckets, jetavators or whatever!

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Was watching Impossible Engineering tonight on Yesterday channel and it was the episode of the Littoral Combat ships, which of course are Libby’s cousins (wouldn’t call them sisters exactly) and there was quite an in depth part on waterjets and quite a few close ups and demonstrations.  Wonder if they have the same ones?  Different ships but possibly the same waterjets installed. 

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7 hours ago, Khaines said:

What does NEX have?

Neither NEX, Manannan or Condor Rapide have reverse buckets. INCAT have never built a vessel over 74m with them even as far back as 1990.

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4 hours ago, captjack said:

The one I was on had Rolls Royce jets, all four were steerable with buckets on all of them.

They'll be the FF or A3 series... Most are now fitted with RR's KaMaWa Sii or Bii series which are bucket free, Austel supply them as a customer option. Many sub 70m vessels are still fitted with steerable reverse buckets.

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10 minutes ago, cvabishop said:

Not sure if it has been mentioned previously but I have heard that the CI have expressed an interest in RMV St Helena when she is made redundant.

It has been mentioned before I rather think.  I don't know if there is a separate thread on the topic.

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Condor Rapide is out of action this coming weekend, just in time for half term. Liberation is to operate the St Malo services in place of Rapide and no fast service between the UK and the islands, with passengers to travel on the Clipper from Portsmouth instead.

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36 minutes ago, joncombe said:

Condor Rapide is out of action this coming weekend, just in time for half term. Liberation is to operate the St Malo services in place of Rapide and no fast service between the UK and the islands, with passengers to travel on the Clipper from Portsmouth instead.

Not sure that is correct, Liberation is operating extra sailings to cover the UK and St Malo

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5 hours ago, northsaul2 said:

Not sure that is correct, Liberation is operating extra sailings to cover the UK and St Malo

Sorry yes you're right, looks like Liberation is operating both the northern and southern routes for a few days.

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