Anyone Interested in Ships

[The Stationmaster]

2 hours ago, Kingzance said:

Thanks Mike, brings back a few memories for me. In the early part of my seafaring life, we used to have a blackboard "on the plates" on which were written important notes for all to see. One such was the acronym LOPOMES. This translated into:
Lube Oil Purifier On Main Engines Sump.

In the lower picture, the green boxes with red / grey metallic labels look like the "Asco" "Red Hat" solenoid valves that were used on automated purifier installations to cause the bowl to open and eject the accumulated heavier sludge that had been "centrifuged" out of the liquid being treated. No doubt the inhabitant of Fraggle Rock and others will confirm or correct me  

Remind me in a few weeks time and I'll ask the appropriate folk the next time we're aboard  - should nobody else confirm in the meanwhile. Plus with any luck I'll get a close-up pic of them if I remember provided the engineer taking the tour doesn't whistle through that area at his usual pace.  

 

For whatever reason we always seem to get plenty of time here during the machinery space tour,  and its fascinating when the ship is in DP (Dynamic Positioning) and the shafts are perpetually changing speed or reversing in order to maintain the ship's position.  And not that it shows in still pictures but it's even more interesting when one shaft is rotating in one direction and the other is rotating in the opposite direction.

 

[Kingzance]

8 hours ago, The Stationmaster said:

Remind me in a few weeks time and I'll ask the appropriate folk the next time we're aboard  - should nobody else confirm in the meanwhile. Plus with any luck I'll get a close-up pic of them if I remember provided the engineer taking the tour doesn't whistle through that area at his usual pace.  

 

For whatever reason we always seem to get plenty of time here during the machinery space tour,  and its fascinating when the ship is in DP (Dynamic Positioning) and the shafts are perpetually changing speed or reversing in order to maintain the ship's position.  And not that it shows in still pictures but it's even more interesting when one shaft is rotating in one direction and the other is rotating in the opposite direction.

 

Mike, I never sailed on any vessel with electric motors driving the propellers, a pre-requisite for DP. More than half my time was on extra large kettles and the rest on diseasals.  Great pics and very interesting to me. As to Asco solenoids, yes, from the 80’s onwards they used much smaller coils embedded in a plastic cube and more exposed mountings.

[The Stationmaster]

3 hours ago, Kingzance said:

Mike, I never sailed on any vessel with electric motors driving the propellers, a pre-requisite for DP. More than half my time was on extra large kettles and the rest on diseasals.  Great pics and very interesting to me. As to Asco solenoids, yes, from the 80’s onwards they used much smaller coils embedded in a plastic cube and more exposed mountings.

Here you go then - 1 x BBC 1270kW motor (starboard side), and below that the commutator and brush assemblies on the port side motor.  There is another set of brushes lower down and apparently you need a particular size of engineer to reach them - there is a female ETO who is normally shore based but reportedly she has just the right flexibility and reach to do the job (according to the Starboard Watch  2nd - who is not female).  Judging by the 3rd on the other watch, and without wishing to appear sexist,  I don't think she would have either the reach or shape as she is a very comely young lass however the ETO on the Port Watch is built like a rake so he can no doubt reach down there with ease.  Oddly, and apropos of nothing, the ETO on each watch is called Paul but the one on the Starboard Watch also mixes a mean version of Pimms No.1 among his other skills.

 

Suppose at some time the big Rustons also need to appear here  - not they are 'big' by large ship standards.

 

 

[The Stationmaster]

Incidentally an amusing aside about large kettles.  When I was working out in Aus in 2004/5 there was an Australian Chinese chap in the LR office who was their only qualified boiler inspector for marine boilers - he held a Commonwealth of Pennsylvania Boiler Inspector's certificate.  Although he didn't get much work in that line there was a coal boat working between Newcastle (NSW) and China which was not only a kettle but was coal fired, so he had occasional trips up there to check it.

[Kingzance]

10 hours ago, The Stationmaster said:

Incidentally an amusing aside about large kettles.  When I was working out in Aus in 2004/5 there was an Australian Chinese chap in the LR office who was their only qualified boiler inspector for marine boilers - he held a Commonwealth of Pennsylvania Boiler Inspector's certificate.  Although he didn't get much work in that line there was a coal boat working between Newcastle (NSW) and China which was not only a kettle but was coal fired, so he had occasional trips up there to check it.

For many Marine Engineers, one option when leaving the salty embrace was to become a surveyor. I believe you could do so with a BoT / DoT 2nd Class Certificate of Competency. I remained on the briny until I had Combined First Class version, but that is 40 years ago now!

[duncan]

Can I ask a couple of questions

How quickly can the shaft be stopped & reversed for dynamic positioning to work ?  Does it not rust twisting in the shaft, or is it not turning fast enough or accelerating / deacc swiftly enough to cause problems ?

[Kingzance]

34 minutes ago, duncan said:

Can I ask a couple of questions

How quickly can the shaft be stopped & reversed for dynamic positioning to work ?  Does it not rust twisting in the shaft, or is it not turning fast enough or accelerating / deacc swiftly enough to cause problems ?

Duncan, I will give you a considered opinion rather than one based on experience. It is that propellers need to revolve to create thrust, faster rotations = greater thrust. If the DP system can interact fast enough, small adjustments with lower requirements for thrust will be necessary to keep station and, as Mike will confirm, she isn’t expected to do DP work in strongly adverse conditions.

You are correct in asking about inducing torque by switching direction but I suspect the motors are fitted with electrical braking that allows a controlled rate of deceleration for each shaft. I don’t know how long this vessel has had DP but she is quite “long in the tooth” (a bit like me) so I guess the concerns you express either do not manifest themselves or have been successfully addressed. I am sure that Mike will confirm she has bow-thrust too! Registered in the U.K., I would think she will be subject to LR classification and DoT standards. If she was being replaced, the propulsion system would probably be based on Vorth-Schneider thrust units which are found in tugs and the Isle of Wight ferries to allow delicate manoeuvring in any direction.

[The Stationmaster]

10 minutes ago, Kingzance said:

Duncan, I will give you a considered opinion rather than one based on experience. It is that propellers need to revolve to create thrust, faster rotations = greater thrust. If the DP system can interact fast enough, small adjustments with lower requirements for thrust will be necessary to keep station and, as Mike will confirm, she isn’t expected to do DP work in strongly adverse conditions.

You are correct in asking about inducing torque by switching direction but I suspect the motors are fitted with electrical braking that allows a controlled rate of deceleration for each shaft. I don’t know how long this vessel has had DP but she is quite “long in the tooth” (a bit like me) so I guess the concerns you express either do not manifest themselves or have been successfully addressed. I am sure that Mike will confirm she has bow-thrust too! Registered in the U.K., I would think she will be subject to LR classification and DoT standards. If she was being replaced, the propulsion system would probably be based on Vorth-Schneider thrust units which are found in tugs and the Isle of Wight ferries to allow delicate manoeuvring in any direction.

Yes. She was built in 1982 (Robb & Co) and the diesel-electric fit is original although some of the electronic cubicles have been seriously updated for obvious reasons.  As it happens her predecessor, of the same name, commissioned in 1938 was also diesel-electric.

From direct observation the change of shaft speed is typical of the output of a DC motor - it speeds up or slows down almost imperceptibly if it is a slight change but more noticeably if there is greater acceleration.   The ship's technical handouts has the following to say about motor control.  'Speed and direction control for each motor is via an ABB DCS500 series 12-pulse thyristor converter supplied from the main 660v switchboard.  The converter rectifies the 660V as to dc by firing the thyristors.  The current supplied to the motor armature is controlled by firing the thyristors for a variable length of time - the field current of the motor is constantand maintained at all times.  By varying the armature current strength, the speed of the motor is controlled;  by changing the armature current polaritythe direction of rotation [is] reversed.  Shaft speed is up to a maximum of 250 revs/mln, giving about 13 knots ship speed.

 

 From observation when the shaft is reversed it momentarily stops before turning in the opposite direction and then accelerates to whatever speed is required.  If you look at Page 2 of this thread -

 

https://www.rmweb.co.uk/community/index.php?/topic/144504-back-on-the-briny-yet-again-april-2019-part-2/

 

you can get a rough idea of the sea conditions when we attended the Foxtrot 3 LV on an emergency call out towards the tail end of 'storm' Hannah.  The sea state wasn't bad although not good enough to safely launch a boat and the wind was still occasionally gusting to Force 5 with the ship in DP as you will read.  Normally they would not be working in that sort of wind and sea as it is too rough for buoy work or routing LV servicing.

 

Patricia has a rather unusual bow thruster in that the type fitted has the motor mounted vertically driving a directional bow thruster.  So in addition to the usual movements towards either beam she can also go ahead or astern using the bow thruster.

 

This view shows the starboard shaft as it emerges from the motor on the left through the thrust bearing (centre) and then onwards to the right to what you saw in the previous view of the shaft.  Unfortunately there's not really enough room to get it all in one view for the camera and the secind picture shows the best I could manage towards a complete view - in this case of the port shaft

 

 

[duncan]

Many thanks, just wondered as even with the open whaler (2 cylinder aircooled), we had to make sure the shaft was stopped before engaging opposite gear, otherwise a significant thump, lurch & wear ! 

[Kingzance]

18 minutes ago, duncan said:

Many thanks, just wondered as even with the open whaler (2 cylinder aircooled), we had to make sure the shaft was stopped before engaging opposite gear, otherwise a significant thump, lurch & wear ! 

Was that the old Lister diesel Duncan?

[jjb1970]

A lot of DP ships use mechanical drive, usually medium speed engine dropped down through a gear box to shafts driving CPPs. A CPP provides a reversible propeller and variable thrust at fixed engine speed (although they can often be operated in a combinatory mode or with pitch fixed and using variable engine speed).

[Kingzance]

36 minutes ago, jjb1970 said:

A lot of DP ships use mechanical drive, usually medium speed engine dropped down through a gear box to shafts driving CPPs. A CPP provides a reversible propeller and variable thrust at fixed engine speed (although they can often be operated in a combinatory mode or with pitch fixed and using variable engine speed).

Absolutely true but CPPs were not widely in use when Patricia was built and therefore the cost of each unit was proportionally very much higher than it would be today. Diesel or Turbo electric was much more widely recognised in the late 70's / early 80's and can be traced back to much earlier in the 20th century with huge numbers of turbo-electric vessels being constructed around the 1930's and 40's.
Propellor blade design is a very complex subject and it is almost impossible to make a blade that is equally efficient in both directions, part of the reason that CPP isn't used ubiquitously. Of course I mustn't forget that submarines used batteries to power their electric shaft motors (DC) providing drive when submerged with diesel engines sometimes being sometimes connected through clutches I believe when the vessel was on the surface (or just below if using the snorkel), although in many cases, one or more diesel prime mover(s) just drove a generator to recharge the batteries.

[jjb1970]

In the case of DP ships the prime requirement of the propulsion system is manoeuvring and station keeping, rather than efficiency. Particularly for ships in the offshore energy sector (which remains the most important segment for DP) they are optimised for stationary position keeping or following a track at an offshore location to undertake work and the principal requirement is the ability to do this in a range of environmental conditions. This is very different to conventional ships which are optimised for efficient transportation. So propeller efficiency isn't as important as it is for conventional ships, many DP ships have Kort nozzles for their propellers which increases low end thrust but kills efficiency and performance at higher speeds. In terms of time, CPPs were in wide use in the 70's, the RRS Bransfield of BAS built in 1970 with 1950's technology had a single screw CPP propulsion arrangement. Something to note also is that DP is the auto position control system, and that probably until the late 90's most offshore vessels and many specialised ships such as buoy tenders used joy stick control with the same manoeuvring arrangements as a DP ship but without the DP positioning control system. Certainly for a conventional ship like a box boat or bulk carrier which operates at steady cruising speeds then a fixed pitch prop is more efficient.

[Bon Accord]

With regard to shafts, it is (or was) common in some of the older twin screw DP fitted vessels that when in DP mode one shaft only worked ahead and the other only worked astern, this being in what we used to call "push/pull mode", the only variation being the revs in use or the pitch on the prop if CPP depending on the required movement. Therefore, the mechanical bits - especially since she's D/E - won't get quite as much of a hammering as you might think.

My knowledge on the matter is somewhat out of date as I've only ever been on one DP fitted vessel (a shuttle tanker) and that was 17 years ago.

[jjb1970]

I found DP ships to be a good example of the fact that a skilled human being is far more capable than some want to believe and also the effect of de-skilling. When I first went offshore a lot of masters and chief officers still practiced manual control and drove the boat in preference to relying on DP. It was obvious in the engine room when we were on DP as it absolutely hammered the engines as the DP system could not read the sea and weather and feel the boat like a good driver could. Some of the older offshore masters and chief officers had staggeringly good ship handling skills and could outperform the DP system using a fraction of the power. Then oil companies demanded that vessels operate on DP, younger deck officer DPOs came through the system not knowing anything other than DP and it entered a circular process of lost skills leading to an even heavier reliance on DP. Now the oil companies realise that core skills have been lost and the safety implications if there is a DP failure and want the old skills recovered overnight. The Nautical Institute has developed a ship handling course, never let an opportunity to sell more training go to waste and all that. 

And people seriously think they can make ships autonomous and still have skilled seafarers who are normally not allowed anywhere near the controls step in and save the day if necessary. Dreamworld time. 

[The Stationmaster]

32 minutes ago, jjb1970 said:

I found DP ships to be a good example of the fact that a skilled human being is far more capable than some want to believe and also the effect of de-skilling. When I first went offshore a lot of masters and chief officers still practiced manual control and drove the boat in preference to relying on DP. It was obvious in the engine room when we were on DP as it absolutely hammered the engines as the DP system could not read the sea and weather and feel the boat like a good driver could. Some of the older offshore masters and chief officers had staggeringly good ship handling skills and could outperform the DP system using a fraction of the power. Then oil companies demanded that vessels operate on DP, younger deck officer DPOs came through the system not knowing anything other than DP and it entered a circular process of lost skills leading to an even heavier reliance on DP. Now the oil companies realise that core skills have been lost and the safety implications if there is a DP failure and want the old skills recovered overnight. The Nautical Institute has developed a ship handling course, never let an opportunity to sell more training go to waste and all that. 

And people seriously think they can make ships autonomous and still have skilled seafarers who are normally not allowed anywhere near the controls step in and save the day if necessary. Dreamworld time. 

Indeed and I have seen this a number of times on Patrica, particularly when things are getting a bit awkward and the skilled and practiced human is a lot more sensitive to wind and tide than the machine.  In fact in the week prior to the one I linked above the Captain went out of DP in an effort to get on a buoy off the Goodwins because of the speed of the tide although the wind wasn't helping - in the end he had to give it up as. bad job because he simply couldn't get into the right position to life the buoy.

 

It has been interesting in the past when TH brought in Captains from outside but with North Sea anchor handling experience and one of them definitely found 1980s style DP was not to his taste, I doubt he ever even tried to do the job without the help of DP,  he was gone within 18 months.

[New Haven Neil]

'fraid all this DP and CP stuff is wayyy over my (one time) lowly pay grade!  Very much only had slow speed direct coupled 'cathedral engine' experience.  I was only a 4th, with 2nd part 1.  Redundancy ended all that. 

 

Those solenoids on the purifiers do look familiar, but the heavy oil purifiers I looked after were a lot bigger than those - and a lot older, the newest ship I sailed on was '77 built.  Lube oil ones of about that size weren't self cleaning, had to do it the hard and dirty way.  

[Kingzance]

1 hour ago, New Haven Neil said:

'fraid all this DP and CP stuff is wayyy over my (one time) lowly pay grade!  Very much only had slow speed direct coupled 'cathedral engine' experience.  I was only a 4th, with 2nd part 1.  Redundancy ended all that. 

 

Those solenoids on the purifiers do look familiar, but the heavy oil purifiers I looked after were a lot bigger than those - and a lot older, the newest ship I sailed on was '77 built.  Lube oil ones of about that size weren't self cleaning, had to do it the hard and dirty way.  

How many years before the mast, man and boy Neil? 
Like you I guess, my oldest ship was built in 1953 and the newest was already seven years old when I joined her in '79. As I had got my full 1st Class Steam ticket before venturing onto direct coupled slow speed weasalls, i avoided the depressing chore of purifier strip-downs on heavy-oil fueled ships.

[New Haven Neil]

7 years, KZ.  I was but a boy.  My ol' dad was a chief, steam and motor, but he was a motor man really.  

[NorthBrit]

Oceania Cruises 'Nautica'  at the Port of Tyne today.  11th June 2019

 

 

[lightengine]

[Kingzance]

So the publicly chosen name of Boaty McBoatface appears on a long range AutoSub 

[lightengine]

Sinky McSinkface would have been better for a pelagic vessel

[duncan]

On 07/06/2019 at 12:42, Kingzance said:

Was that the old Lister diesel Duncan?

 

I think it might have been, 40 + yrs ago, also too busy handling it in confined areas !

[johnofwessex]

1 hour ago, duncan said:

On 07/06/2019 at 12:23, duncan said:

Many thanks, just wondered as even with the open whaler (2 cylinder aircooled), we had to make sure the shaft was stopped before engaging opposite gear, otherwise a significant thump, lurch & wear ! 

I think it might have been, 40 + yrs ago, also too busy handling it in confined areas !

 

The '3 in 1' whalers had the Enfield H02 flat twin 2 cl engine, with a 2 speed in each direction & neutral control lever which my lot (Bristol Grammar School CCF) just moved with your foot.

 

Balmoral had a hand started H02 on the emergency pump in the steering flat, having tried God Only Knows how you started it