# Variable Pitch Propellors.



## OLD STRAWBERRY

Straight forward question. Was it possible for Steam Driven vessels, Tugs especially, to have Variable Pitch propellors??.


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## A.D.FROST

YES,a bent answer to a straight question


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## Robin Craythorn

The controllable/variable pitch propeller system was operated hydraulically with an electric pump providing the power, so was independent of the main propulsion
system be it steam or motor, I was Master for several years with twin c.p.p propellers and found that if you used zero pitch you immediately lost steerage control because of the now spinning flat disc immediately aft of the rudder, a setting of 2 ahead would immediately restore steering control


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## uisdean mor

Robin Craythorn said:


> The controllable/variable pitch propeller system was operated hydraulically with an electric pump providing the power, so was independent of the main propulsion
> system be it steam or motor, I was Master for several years with twin c.p.p propellers and found that if you used zero pitch you immediately lost steerage control because of the now spinning flat disc immediately aft of the rudder, a setting of 2 ahead would immediately restore steering control


Any propellor working aft of a rudder is doing a very good job. Not only hydraulics but spring loaded hubs could be used manually - usually in an emergency but early designs do exist where mechanical systems were possible.


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## Dartskipper

Hundested vp propellers with mechanical control were popular with Scandinavian fishing vessels and workboats. I imagine they could have been used with steam engines as they were commonly installed on vessels with slow revving diesel or semi diesel engines. We had a pair fitted to the auxiliary ketch Orcella, but these were set to be fully feathered to reduce drag when under pure sail. The shafts had locking devices fitted to prevent any rotation when the props were feathered. When resetting the pitch, a fairly rudimentary scale gave an indication of what angle the blades were, and a pyrometer on each engine indicated the load. (She was twin screw). After arrival at her home in Seattle, modifications using aircraft flap motors and angle indicators were installed to improve the ease of changing the pitch.


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## OLD STRAWBERRY

Thanks all. Question arose whilst chatting about old Naval/PAS Steam tugs of the "Samson" Class. Evidently some did and some didn't. Thanks for the info' Boys.


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## howardws

Robin Craythorn said:


> the now spinning flat disc immediately aft of the rudder, a setting of 2 ahead would immediately restore steering control


I'm having difficulty in visualising a drive train that would allow a ship's propeller to be aft of it's rudder!


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## lakercapt

I sailed a boat on the "Lakes" that had been converted from a turbine engine to a direct drive diesel and it was a nightmare to steer.
Before the turbine never stopped the propeller always turning and a wash going over the rudder which did allow some steerage way at stopped.
When the diesel stopped all wash then stopped over the rudder and it had next to no effect as it was too small in these conditions.
With variable pitch propellers you had infinite control and could have early zero pitch and still steer.


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## Derek Roger

A bit of a misnomer here ; almost all propellers have a variable pitch unless is is an Archimedes screw .
What is being discussed is a controllable pitch propeller ; two different things .
A controllable pitch prop also has a variable pitch .

Not knowing the difference is a good way to fail Chiefs orals . Derek


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## Satanic Mechanic

Derek Roger said:


> A bit of a misnomer here ; almost all propellers have a variable pitch unless is is an Archimedes screw .
> What is being discussed is a controllable pitch propeller ; two different things .
> A controllable pitch prop also has a variable pitch .
> 
> Not knowing the difference is a good way to fail Chiefs orals . Derek


A point of much discussion as it can be argued that while different sections of a blade do indeed have different pitches the prop overall has just a single pitch and that a controllable pitch propeller blade is the same but the overall pitch can be varied. Basically semantics . I happily use both terms interchangeably though I never use the term VPP


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## spongebob

Brings back to mind the Kitchener rudder .

Bob


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## Derek Roger

Satanic Mechanic said:


> A point of much discussion as it can be argued that while different sections of a blade do indeed have different pitches the prop overall has just a single pitch and that a controllable pitch propeller blade is the same but the overall pitch can be varied. Basically semantics . I happily use both terms interchangeably though I never use the term VPP


Forgive my being pedantic ( To quote Chick Murray " Its just my ways " )
Normally a CP prop under hydraulic failure has a heavy spring which puts the pitch to ahead ; and this can be locked as a get home device .
We built a tug at Saint John Shipbuilding ' the Irving Elm in 1980 which is still in operation . She had a Lohman and Stolterfoht CP system ; the weakness was that if a hydraulic failure occurred she went to full astern .
The inevitable happened which towing a barge a failure occurred and the tug went full astern into the tow with substantial damage .

Derek


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## BOB.WHITTAKER

Dive Support Vessel " Uncle John " had eight variable pitch propellors , two for ahead and astern and six for sideways , electricaly driven with 6kv motors from five V18 Hedemora diesel driven alternators . These to serve the dynamic positioning system . It is now almost 40 years on and my memory is not absolute on this and I'm not sure whether they were spring loaded one way or the other , but what did happen on hydraulic failure was the propellor would go creep to full pitch in whatever direction it was in at the time of the failure . This led to very interesting situations with divers on the sea bed and the vessel positioned 15 - 20 metres of a platform . The vessel would start to rotate like a merry go round , other propellors would respond , more load
on the board , standby engines would start and synchronise automaticaly 
adding more power for the system to play with . Dive control pulling the divers back to the bell and then retrieving the bell and the operators in the DP control restoring order . There were situations that had not been considered , fortunately , to my memory at least , order was always restored .


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## A.D.FROST

Original variable pitch propellers fail safe was ahead (get you home) until the MANCHESTER COURAGE(photos in Gallery)rammed the lock gates in the Manchester sship canal and emptied it.


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## howardws

On the KaMeWa CPPs in P&O Southern Ferries 'Eagle' and 'Dragon' it was possible to jack the pitch into 'ahead' as a get you home. We discovered in 'Eagle' that if you neglected to remove a certain vent plug when testing the system you could stretch the control rod inside the shaft by 4 inches, thus enabling the propeller to only run at full astern pitch!


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## david freeman

steam up and downer with a fixed pitched propeller for a tug- immediate manoeuvrability ahead and astern. The nearest to this, but restricted in bollard pull is the voith synder propeller unit. Ok for a harbour tug.


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## sternchallis

Due to the large hub of a CPP you do lose thrust as compared to a fixed pitch propellor. So for an ocean going ship a fp prop is better, but for a short sea trader with a lot of docking, such as cross channel ferries and perhaps cruise ships (that are glorified coasters and don't go deep sea as opposed to a passenger liner).
During the 1988 IMareEng IMASS conference on Cruise Ships there was a speaker from KameWa extolling the virtues of CPP, in the Q&A session quite a lively debate ensued, I suppose similar to the sail/steam debate at the time.
It is a case of using the correct prop for the duties of the vessel by lifetime costing of both systems.

Whilst serving my apprenticeship on Hull Fish Dock in 68-73 , I watched the overhaul of CP props and yes there was a darn great spring (similar to those fitted on early B&W exh valve engines about 18"diameter), which put the pitch into ahead in case of hydro-mechanical failure. 
The industry was changing from steam sidewinders to diesel and also to diesel Stern Freezers/factory ships which were fitted with the CP prop.

A vessel with a CP prop does require a complicated governor system, a steam recip engine on a tug probably is not fitted with governor, just a hand operated flap valve inthe HP steam line. Though CPP is possible, it is a rather complicated system on a basic engine that requires a lot of hands on to operate.
A tug requiring a high bollard pull needs an efficient prop with a fixed pitch does.

Just to go off topic slightly.
The late United Towing Company from Hull, bought an ocean going tug (Statesman) from the Japanese (I think), built by the US. This had twin CP props(or was it quad) with reduction gearboxes driven by twin v- bank engines (about 18 cylinders per engine). It also had several/countless v- bank diesel alternators. The engines I believe were Detroit Diesels or GM of two different sizes and typical of US thinking more cubic inches the better, hence so many engines. We would have fitted large slow revving 4 strokes not all these little screamers with goodness knows how many units. Cylinder heads were aluminium, though considering the number you would have to hump about just as well.
She was the most powerful tug in the world at the time about 1972. She had good lines and the bridge/ accomodation looked like a liner rather than a boxy tug. 
I may have put the thumbnail image up on the tug section, showing her on speed trials in the Humber after her complete overhaul by all the ship repair companies in Hull. We all got a slice of the cake.


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## howardang

sternchallis said:


> Due to the large hub of a CPP you do lose thrust as compared to a fixed pitch propellor. So for an ocean going ship a fp prop is better, but for a short sea trader with a lot of docking, such as cross channel ferries and perhaps cruise ships (that are glorified coasters and don't go deep sea as opposed to a passenger liner).
> During the 1988 IMareEng IMASS conference on Cruise Ships there was a speaker from KameWa extolling the virtues of CPP, in the Q&A session quite a lively debate ensued, I suppose similar to the sail/steam debate at the time.
> It is a case of using the correct prop for the duties of the vessel by lifetime costing of both systems.
> 
> Whilst serving my apprenticeship on Hull Fish Dock in 68-73 , I watched the overhaul of CP props and yes there was a darn great spring (similar to those fitted on early B&W exh valve engines about 18"diameter), which put the pitch into ahead in case of hydro-mechanical failure.
> The industry was changing from steam sidewinders to diesel and also to diesel Stern Freezers/factory ships which were fitted with the CP prop.
> 
> A vessel with a CP prop does require a complicated governor system, a steam recip engine on a tug probably is not fitted with governor, just a hand operated flap valve inthe HP steam line. Though CPP is possible, it is a rather complicated system on a basic engine that requires a lot of hands on to operate.
> A tug requiring a high bollard pull needs an efficient prop with a fixed pitch does.
> 
> Just to go off topic slightly.
> The late United Towing Company from Hull, bought an ocean going tug (Statesman) from the Japanese (I think), built by the US. This had twin CP props(or was it quad) with reduction gearboxes driven by twin v- bank engines (about 18 cylinders per engine). It also had several/countless v- bank diesel alternators. The engines I believe were Detroit Diesels or GM of two different sizes and typical of US thinking more cubic inches the better, hence so many engines. We would have fitted large slow revving 4 strokes not all these little screamers with goodness knows how many units. Cylinder heads were aluminium, though considering the number you would have to hump about just as well.
> She was the most powerful tug in the world at the time about 1972. She had good lines and the bridge/ accomodation looked like a liner rather than a boxy tug.
> I may have put the thumbnail image up on the tug section, showing her on speed trials in the Humber after her complete overhaul by all the ship repair companies in Hull. We all got a slice of the cake.


The UTC Tug you mention was "Statesman" (ex "Alice Moran"), certainly one of the most powerful tugs in the world at the time but "Lloydsman" , built in 1970 was larger and a little more powerful. Both of them were beautiful ships.

Howard


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## BOB.WHITTAKER

KaMeWa Side Thrusters DSV Uncle John
Feed back , to give actual pitch position from the hub mechanism to the Hunting Mechanism on the hydraulic control unit , was from a bearing in the centre of the rotating crosshead that moved the blades , the bearing was
some 50mm od X 20mm id , probable cost about £15.00 . In the centre of the bearing was a stationary pin 20mm dia with a roller chain connected to it.
The chain passed over two or three sprockets to another pin that ran in seals
to exit the the body of the thruster . A further length of chain then drove the
hunting mechanism and potentiometer . The chain both internal and external
to the hub , from memory , being a similar size to the drive chain of a bicycle .

Failure of the £15.00 hub centre bearing resulted in the stationary pin rotating which then snapped the chain . Thus no feedback and no control . This happened on two of the thrusters , one a tunnel thruster in one of the hulls 
which was permanently submerged , the other in a nozzle thruster which was
exposed at transit draught . This resulted in a trip off the field to Yell Sound in
the Shetlands where the onboard crew stripped the hub and rebuilt it . Hull freeboard at the time was at most 12" and at times water up to your waist. A successful repair was carried out .


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## sternchallis

There is a moral there somewhere.


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## Derek Roger

The controllable pitch propeller was invented in Rothesay New Brunswick at that time for aircraft propellers ; gentlemans name was Wallace Turnbull .It was first tested in flight in 1927. At that time it was patented as a variable pitch propeller .


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## Varley

I 'felt' that date much too late and related to aircraft developments. One can Google a reference to a variable pitch propeller of 1849 by Griffiths and wonder if another member can do better.

I am also sure that the technique was used in small boats for altering direction (presumably after the introduction of the internal combustion engine as reciprocating steam was easy enough to reverse on the prime mover).

Altering blade angles, 'on the move' as it were, would not have taken the marine fraternity by much surprise as later paddle technology had several variations on the theme.


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## Bill Morrison

KaMeWa V.P.P.
From memory the only problem we had was the forming of microbes in the hydraulic oil which rendered the system inoperable. I think it was a Shell oil but can't remember type or grade. The main spring set the blades to full ahead thus giving some control. Having a bow thruster help with manoeuvring.

The diagrams have some information of the system.


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## sternchallis

Thanks Bill, 
Allways wondered how these worked, even though I have seen a few stripped down in the drydock. I was probably a bit young at the time to ask or understand as a 17 year old apprentice. The fitters wouldn't have known, we always had a makers man down to supervise and do critical parts.
Most of the CPP 's were Stone Manganese Marine, but same design.

I remember once they opened one up and boss on which one of the blades was attached had cracked in the step section , ie at the base of the small diameter boss.
Now if that blade would have come off at speed it would have spoiled somebodies day and probably holed the hull. My guess they probably caught a bit of ice.
Stern trawler up in Greenland or Barents sea.


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## uisdean mor

sternchallis said:


> Thanks Bill,
> Allways wondered how these worked, even though I have seen a few stripped down in the drydock. I was probably a bit young at the time to ask or understand as a 17 year old apprentice. The fitters wouldn't have known, we always had a makers man down to supervise and do critical parts.
> Most of the CPP 's were Stone Manganese Marine, but same design.
> 
> I remember once they opened one up and boss on which one of the blades was attached had cracked in the step section , ie at the base of the small diameter boss.
> Now if that blade would have come off at speed it would have spoiled somebodies day and probably holed the hull. My guess they probably caught a bit of ice.
> Stern trawler up in Greenland or Barents sea.


On a similar vein - Houston Ship Canal. Making a turn in darkness to move back down when we encountered a loose channel buoy and a subsequent amount of heavy duty chain. Single screw KaMeWa but twin engine Peilsticks. We lost one blade due to fractured boss and when we drydocked it became obvious the actual hub was also damaged beyond repair.. At the time we were motoring (sic) on one engine as the other one was stripped down for removal of the main crankshaft due to a crankcase explosion leaving Chittagong. I do not know what I did with my spare time on that ship. (K)


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## sternchallis

Hmm,
Some people get all the fun!

Pielsticks, goodness me what had you done to deserve being landed with those.

As one old chestnut says, "Never join a ship with an engine begining with "P", such as Paxmans, Pielsticks and PDoxfords".

They wouldn't know they are born the engineers of today on some of the engines and situations we had to put up with in our day.


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## Derek Roger

uisdean mor said:


> On a similar vein - Houston Ship Canal. Making a turn in darkness to move back down when we encountered a loose channel buoy and a subsequent amount of heavy duty chain. Single screw KaMeWa but twin engine Peilsticks. We lost one blade due to fractured boss and when we drydocked it became obvious the actual hub was also damaged beyond repair.. At the time we were motoring (sic) on one engine as the other one was stripped down for removal of the main crankshaft due to a crankcase explosion leaving Chittagong. I do not know what I did with my spare time on that ship. (K)


Mahsud or Maihar Hugh ?


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## uisdean mor

Derek Roger said:


> Mahsud or Maihar Hugh ?


Maihar - Charlie Bald flew out to Galveston to run the drydock - which did not go well as they knew they had us over a barrel. Hub had to be manufactured back in Sweden which took some time. In that time the crankshaft was replaced. I flew home from Galveston towards the end so did not experience sea trials - which I am sure were a test of nerves. Lots of crankcase time on the Pielsticks as also stood by the tankers as the Napiers were changed out for ABB and we took the chance of updating all main engine work. If memory serves me right I think we trialed a new version of exhaust valve body during that time as well. All a long time ago.


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## uisdean mor

sternchallis said:


> Hmm,
> Some people get all the fun!
> 
> Pielsticks, goodness me what had you done to deserve being landed with those.
> 
> As one old chestnut says, "Never join a ship with an engine begining with "P", such as Paxmans, Pielsticks and PDoxfords".
> 
> They wouldn't know they are born the engineers of today on some of the engines and situations we had to put up with in our day.


Interesting work all the same. Once the decisions are made re what needs doing then a plan falls into place and we work through it. Some satisfaction in overcoming the logistics and being able to run the plant as close to what it should do. Albeit with Peilsticks the wear rates were so bad that good times never lasted long. Character forming??? There were worse times to come with Russian designed , Yugoslav built B&W and more V18 Peilsticks. But that is another story as they say


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## Don A.Macleod

Derek Roger said:


> Mahsud or Maihar Hugh ?


Very interesting and in contrast we arrived at Houston from Japan (late '69 on Mahsud) tugs were on strike but as we had CPP and bow thruster we were allowed to go up the canal under our own"STEAM". It was early evening but dark and when the old man (Watson Ross) came down to the bar after docking he said the pilot was very impressed with our manouverability. Wonder if it was the same pilot Hugh!


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## Bill Morrison

This has turned into a very interesting discussion started by " Old Strawberry."
As KaMeWa is the only type I have had any experience of, I was surprised to come across an advert while browsing in The Motor Ship of July 1947. It was for a Rotol variable pitch & reversing propeller for a small harbour tug, will down load it.
I have also been searching the internet for information on Rotol Ltd Gloucester. The only thing seemed to be the aviation industry, no marine side and then came across this post. Saunders Roe (Anglesey) MTB 539 it contained mention of a Rotol propeller. This is one for the R.N. boys but really worth a look. dave-mills.yolasite.com/saunders-roe-mtb.php
Bill


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## uisdean mor

Don A.Macleod said:


> Very interesting and in contrast we arrived at Houston from Japan (late '69 on Mahsud) tugs were on strike but as we had CPP and bow thruster we were allowed to go up the canal under our own"STEAM". It was early evening but dark and when the old man (Watson Ross) came down to the bar after docking he said the pilot was very impressed with our manouverability. Wonder if it was the same pilot Hugh!


Hello Don . sorry no idea of the pilot. Master was - I want to say Dennis?? MacManus but could be wrong. The interesting bit about the whole escapade( for a Stornowegian such as yourself) was that on the way over we called into Mombassa for tea and Johnie Bain flew out to "verify" that the crankshaft was actually bent. There was a train of thought that they were relatively short and robust that yes then could be damaged surface wise but not bent. Well this one was bent and "scratched". Spent two days in and out of the crankcase with Johnie and he eventually agreed. After that he did treat us to a night out up the town. Met him a few years later on Goat Island when I was working as engineer on the Mallaig purser Silvery Sea. But that as they say is another story. Slainte


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## Steve Oatey

Derek Roger said:


> A bit of a misnomer here ; almost all propellers have a variable pitch unless is is an Archimedes screw .
> What is being discussed is a controllable pitch propeller ; two different things .
> A controllable pitch prop also has a variable pitch .
> 
> Not knowing the difference is a good way to fail Chiefs orals . Derek


Agreed Derek. The wind is often described as "light,variable" but that does not mean it can be altered. They're known as CPPs for a reason.


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## BOB.WHITTAKER

*Variable Pitch*

We all know exactly what is being refered to as " Variable Pitch " in
this thread .


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## Don A.Macleod

uisdean mor said:


> Hello Don . sorry no idea of the pilot. Master was - I want to say Dennis?? MacManus but could be wrong. The interesting bit about the whole escapade( for a Stornowegian such as yourself) was that on the way over we called into Mombassa for tea and Johnie Bain flew out to "verify" that the crankshaft was actually bent. There was a train of thought that they were relatively short and robust that yes then could be damaged surface wise but not bent. Well this one was bent and "scratched". Spent two days in and out of the crankcase with Johnie and he eventually agreed. After that he did treat us to a night out up the town. Met him a few years later on Goat Island when I was working as engineer on the Mallaig purser Silvery Sea. But that as they say is another story. Slainte


Hi Uisdean from the glorious Isle of Lewis and just finished demolishing a plateful of newly caught Stornoway herring! Tried to visualise you and Johnnie Bain together in a Pielstick crankcase! You desrved a medal for that! 

Didn't kmow him very well as I only did a couple brief spells on the coast with him but he was a high quality man, everything had to be perfect I believe.

To establish that a Kobe Steel c'haft was bent took some precsiion work. Must have been some "bang ". Do you ever come up this way nowadays? 

Slainte Donald


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## Derek Roger

My last trip on a Tanker was Lustrous Dubai to Stendngsond ; Johnny was the super who met us there . He took me out for a very nice dinner before I flew home and all the conversation was about the turbo chargers . At the end I think I had him convinced that a retrofit to Brown Boveri would solve a lot of the charter speed problems .
The next time I saw him was when I resigned to emigrate to Canada ; he did his best to try and make me change my mind and again provided a very nice dinner . No regrets ; who was to know then what was about to happen to the Brocks fleet ?
I always got on well with John ; he was a good engineer . Last I heard of him he was a "Big Wig " in the Highlands and Islands development board .


Cheers Derek


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## uisdean mor

Don A.Macleod said:


> Hi Uisdean from the glorious Isle of Lewis and just finished demolishing a plateful of newly caught Stornoway herring! Tried to visualise you and Johnnie Bain together in a Pielstick crankcase! You desrved a medal for that!
> 
> Didn't kmow him very well as I only did a couple brief spells on the coast with him but he was a high quality man, everything had to be perfect I believe.
> 
> To establish that a Kobe Steel c'haft was bent took some precsiion work. Must have been some "bang ". Do you ever come up this way nowadays?
> 
> Slainte Donald


Hi Donald , Good to hear from you. Sadly flying a desk these days and rarely get round my old haunts. The talk of the steamie is all broadband and bespoke solutions to suit geography and climate. Working quite a bit with academics on peatland and carbon sequestration and if the latest Barvas buy out completes then maybe there might be room for a wee visit. There may also be a project brewing in Skigersta so you never know. You make me envious with the herring but not to be outdone an old uncle of my wifes has found a source of sea trout not far from the croft and I am going to have a few days down with him next week. I like the finnocks best but he tells me the average is about 2 lbs - so reasonable fish. I will let you know how I get on. Slainte


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## littoralcombat

To clarify, Controllable Pitch Propellers are those (the clue's in the name) whose Blade Pitch can be Mechanically altered (controlled) whilst underway. The term Variable Pitch refers to those Props whose Blade Pitch can be adjusted, but not during operation, i.e the individual blades can be rotated on the hub to 'Fine Tune', probably no more than a few degrees, in order to get maximum efficiency (in dock or alongside only). Even with today's complex computer modelling, nothing can predict the exact performance of the 'Real Deal' once installed.
I believe the Props for the two new RN Carriers have this feature.

Regarding Emergency situations, the RN CPP on the Type 21, 22, 42 classes had a feature that, in the case of of a Hydraulic failure (blown seals somewhere), the pitch could be altered and locked in a usable state to get home. This involved mechanically turning the Oil Transfer Tubes running from the Oil Transfer Box on the Gearbox to the Hub, which in turn would move the actuator and rotate the blades. In practice though, there was a huge amount of stress and twisting of the Tubes and use of this was virtually forbidden in Peacetime unless in extreme situations. Better to get a tow rather than risk severe damage to the mechanism.


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## A.D.FROST

There are that many variable answers and getting out of control,so I thought I would pitch in with two adds from 'Shipbuilder' Marine Engine -Builder of Jan 1959.So you pay's your money and take your choice. CCP or VCP


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## Varley

#38. The last (and only) time I had anything to do with a vessel with such facilities it was a matter of fairly strict 'convention' they be referred to as adjustable pitch. Controllable and variable are in common usage for the 'normal' animal.

Should anyone design a propeller with a variable attribute similar to the meteorological meaning in "winds light to variable" or indeed a method of making the wind controllable as with a "controllable pitch propeller" I have no doubt the semantic distinction would become more important.

If this is a P&Oh or The Cunard versus the rest which is to be the posh description and which the peasant?


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## Duncan112

Technically even cast propellers with fixed hubs have a variable pitch in that the pitch is not constant between the root and blade tip or even across the blade width. 

As regards CPP failure modes five modes have been used at various times 

Full Ahead Pitch - usual and allows vessel to complete Voyage at normal service speed 

Full Astern Pitch, - at least you won't plough into whatever is ahead but shock load on drive train may be significant 

Current Pitch Setting - reasonable and probably the preferable option 

Neutral- possibly safe but you ain't going anywhere fast.

Small Ahead Pitch- maintains some steerage but not going anywhere fast.

Only experience I had of failure was in the clutch to the gearbox, failure mode didn't matter as the Port shaft wasn't moving -


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## woodend

Remember well the first I docked one into P.E., in fact I still have the post card the Captain gave me. She was the Unicorn tanker 'BUFFALO' docking first discharge port on her maiden voyage. The image the post card shows is a beautiful oicture of a good South African BUFFALO and the Captain has written 'Not only is she called one but she handles like one!' As I remember she really did![=P]


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## Derek Roger

Duncan112 said:


> Technically even cast propellers with fixed hubs have a variable pitch in that the pitch is not constant between the root and blade tip or even across the blade width.
> 
> As regards CPP failure modes five modes have been used at various times
> 
> Full Ahead Pitch - usual and allows vessel to complete Voyage at normal service speed
> 
> Full Astern Pitch, - at least you won't plough into whatever is ahead but shock load on drive train may be significant
> 
> Current Pitch Setting - reasonable and probably the preferable option
> 
> Neutral- possibly safe but you ain't going anywhere fast.
> 
> Small Ahead Pitch- maintains some steerage but not going anywhere fast.
> 
> Only experience I had of failure was in the clutch to the gearbox, failure mode didn't matter as the Port shaft wasn't moving -


Thank you for that support Duncan again clarifying variable pitch on a fixed hub cast prop .
Even controllable pitch props have a variable pitch over the blade length .


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## Don A.Macleod

Derek Roger said:


> Thank you for that support Duncan again clarifying variable pitch on a fixed hub cast prop .
> Even controllable pitch props have a variable pitch over the blade length .


It was dinner time in the saloon and the ship(Maihar on passage Vancouver to Japan) suddenly started to surge gently in a fore and aft motion, we all looked at each other and then the alarm went off.

The usual dash to the E/R and found an o-ring as I remember, had blown and caused loss of pitch due to low hydraulic pressure. Repair was initiated promptly and we were up to speed again in jigtime. The only time I witnessed a prop failure on these ships but it was short lived

I think you had just been releived by us Derek so you missed that wee hiccup!. Donald.


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## uisdean mor

Don A.Macleod said:


> It was dinner time in the saloon and the ship(Maihar on passage Vancouver to Japan) suddenly started to surge gently in a fore and aft motion, we all looked at each other and then the alarm went off.
> 
> The usual dash to the E/R and found an o-ring as I remember, had blown and caused loss of pitch due to low hydraulic pressure. Repair was initiated promptly and we were up to speed again in jigtime. The only time I witnessed a prop failure on these ships but it was short lived
> 
> I think you had just been releived by us Derek so you missed that wee hiccup!. Donald.


Hi again Donald. "O" ring must therefore have been part of the control gear either on the bridge or down the tunnel where a manual option was also available. My memories of actually pulling the hub are that the most testing time was splitting the KaMeWa collar on the shaft Intermediate shafting removed or drawn back to allow access then catch bolts screwed into the shaft end plate with copper tubing as shock absorbers then with miniscule bespoke hydraulic pumps push pressure between the collar and the shafting until the collar flew off. In reality really safe as the distance to move was small and surface area so large that as soon as pressure was released the hub only had to move a few thou but it did make a fair racket as it released. Great amusement at shoreside hammer signals between dockside and in the tunnel - One i seem to remember (sic) was "shave and a haircut 2 bits" Interesting times on these "unmanned" vessels. 
Rgds


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## Derek Roger

uisdean mor said:


> Hi again Donald. "O" ring must therefore have been part of the control gear either on the bridge or down the tunnel where a manual option was also available. My memories of actually pulling the hub are that the most testing time was splitting the KaMeWa collar on the shaft Intermediate shafting removed or drawn back to allow access then catch bolts screwed into the shaft end plate with copper tubing as shock absorbers then with miniscule bespoke hydraulic pumps push pressure between the collar and the shafting until the collar flew off. In reality really safe as the distance to move was small and surface area so large that as soon as pressure was released the hub only had to move a few thou but it did make a fair racket as it released. Great amusement at shoreside hammer signals between dockside and in the tunnel - One i seem to remember (sic) was "shave and a haircut 2 bits" Interesting times on these "unmanned" vessels.
> Rgds


On the OD box there was a small filter ( strangling hole filter ) which had to be cleaned / checked regularily ; if this plugged up the pitch would go to full ahead . That is what happened to Mahsud when she hit the dock wall in Colombo putting back the bow 22ft . Had to sail to Hong Kong for repairs ; Class allowed her to sail in the damage condition as the collision bulkhead was intact.Allan Attack flew out and took her to drydock ; I have some pictures of the damage which I will post when I lay my hands on them . The old man was demoted ; he could have clutched out or used the emergency stop ; he only informed the engine roon at the last minute and Davie Meek cluched out but it was too late .


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## sternchallis

Great amusement at shoreside hammer signals between dockside and in the tunnel - One i seem to remember (sic) was "shave and a haircut 2 bits" Interesting times on these "unmanned" vessels. 
Rgds[/QUOTE]
As an apprentice often did the odd drydock job and remember the hammer signals.
Something like ,
1 knock -Ahead
2 Astern
3 Shaft In 
4 Out

7 smoko or tea up!!
So we had to clamber up the dockyard steps then down the gangway, by which point we were ready for a cuppa.


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## skilly57

Duncan112 - I've got another failure mode for you.
Stone Manganese Marine "Seffle" type CPP - each blade about 750 Kg - doing about 167 rpm - dinner time one peaceful night in August 1984, off Nelson, NZ, on arrival from Brisbane, Australia. Master (R.I.P.) decided to do a control check while approaching harbour limits - masts started to leap around a bit, accommodation started moving as well - rushed below and found O.D. box & muff coupling seemingly doing large eccentric circles. Master refused to allow clutches to be pulled until alongside wharf (over an hour). Finally stopped shaft, trimmed ship down by head, engaged turning gear, and told 3/E to start rolling the shaft. Blade 1 - Ok. Blade 2 - Ok. Blade 3 - had to ask 3/E over VHF why he had stopped the turning gear - "I haven't stopped it at all", he replied. Oh F#*K!
One blade had snapped off inside the hub, and all the others were cracked in the same root area!
Ship towed to Wellington (130 miles away) - then laid up there for 6 months awaiting new propeller from SMM. Stern tube bearings also stuffed - flown back to UK for re-metalling as well.
I have a vague recollection of working out the out-of-balance couple at the time - was about 298 tonnes - explains the unhappy stern tube bearings!
1985 replacement propeller continued cracking blades - eventually replaced prop & shafting with Berg system in 2003 - should have gone RR Kamewa though. 
The ship is still running today (having now carried 10.4 million tonnes of cargo), still with the original operator, but now 38 years since keel was laid, so replacement finally on the horizon at the end of this year.
Last photos shows active rudder - 4 tonne thrust from rudder motor & propeller is very handy stern thruster & emergency propulsion system - power is supplied by cables coming from steering flat via hollow rudder stock, as do hydraulic pitch control hoses.
I sailed from 1979 - 1990 on her, and have been back on again since August last year. A bit like pulling one's old comfy slippers on again!
Skilly


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## sternchallis

And as Lt. Philips would say " Oo Narsty" regarding the stern tube bearing.

For those old enough to remember the Navy Lark and HMS Troutbridge.
Still heard occassionaly on Radio 4 Xtra.
Left hand down a bit. Crash.


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## NoR

Were I a shipowner I wouldn't have anything to do with CCP unless operating ferries, tugs/OSV. The list of shipowners who invest in unnecessarily complex equipment which breaks down expensively and inconveniently is a very long one.

I would go for tried, tested and reliable before anything else. Oh, and one other thing. All the kit must be inboard so that the crew have at least a fighting chance of fixing it..........I guess that rules out pods.


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## Varley

For many years DNV required CPP on vessel with a shaft generator - regardless of the technology used to generate.


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## NoR

With CPP _(of which I know very little)_ is there a connect between engine power and pitch. That is to say as pitch is increased or decreased is engine power adjusted accordingly. For instance many prop driven aircraft have constant speed units whereby pitch is altered to maintain constant RPM within certain power settings. In the case of engine failure it's important to feather the blade asap to avoid drag as the pitch fines off to maintain RPM as power decays. So I wonder if it is possible to feather a CPP to reduce drag in the event of engine breakdown in a ship with two or more props.


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## Derek Roger

NoR said:


> With CPP _(of which I know very little)_ is there a connect between engine power and pitch. That is to say as pitch is increased or decreased is engine power adjusted accordingly. For instance many prop driven aircraft have constant speed units whereby pitch is altered to maintain constant RPM within certain power settings. In the case of engine failure it's important to feather the blade asap to avoid drag as the pitch fines off to maintain RPM as power decays. So I wonder if it is possible to feather a CPP to reduce drag in the event of engine breakdown in a ship with two or more props.


CPP can run either at constant revs and adjust the pitch to adjust speed or in some cases when fitted with a " combinator " the prop speed and pitch are combined to give the most fuel efficient result over all engine speeds .
Regards Derek


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## skilly57

NoR, 
The photo of the 400 hp rudder motor in post #48 shows the 4 blades in the feathered position (ie., "stowed position"), so there is no drag. On start up (not initiated unless ship speed is below 6 knots), the hydraulic pump turns the blades through 90 degrees, then the electric motor starts with the blades at Zero pitch. The master can then apply Ahead or Astern pitch as required, although most only apply Ahead pitch, then turn the rudder 80 degrees either way to get thrust in the desired direction.
I have sailed on around 12 ships with CPP - unless they have shaft alternators fitted, the CPP is generally fitted with Combinator Control so the rpm & pitch are applied together. Some also have the Constant Speed option as well as Combinator Control, but using the latter enables the option of applying greater pitch at a lower shaft speed, so is more economical on fuel and often drops the engines out of the resonant rpm range, making the engine room a nicer place to work in and stopping the accommodation from shaking.

Skilly


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## Derek Roger

All the Brocklebank / Moss Tankers had shaft alternators so ran at constant speed . On Maihar and Mahsud the shaft alternator was used for the bow thruster and at sea for electrical supply allowing the generators to be shut down which was a blessing as we had Paxmans which were a nightmare .
On the tankers one main engine was run in port with a shaft alternator to provide power for the cargo pumps which negated the need for a big hot inefficient boiler and steam plant to run the cargo pumps ; also provided enough waste heat to use the ex gas boiler for domestic steam supply . Quite a neat set up .
Derek


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## Varley

Derek,

Indeed, but now well-dated technology allowed that without the shaft remaining at constant speed (and so seeming to need CPP). Paxmans were not a pre-requisite but strangely that is where I first came across them too (not "them" for SGs. "It" for the Paxman!).


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## OLD STRAWBERRY

Well done Boy's at leats my original question seems to have taken off. My original question related to the old "Samson" class steam tugs(MOD) did they have variable pitch propellors. Was it a question of some did and some didn't. Not sure if I had a reasonable answer as yet. Were old steam tugs able to have CPP or VP propellors??.


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## Jim S

Re the Samson Class 3000 hp tugs built 1953/54 in Aberdeen although it was possible there would have been no real advantage in equipping them with Controllable Pitch Propellers - Steam Reciprocating engines being capable of good manoeuvring capability. Additionally the class were twin screw albeit with a single rudder.
The cost alone would not have been favourable.

Jim S


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## OLD STRAWBERRY

Hi Jim thanks for that. I did have cause to wonder. I had been talking to a friend who was convinced that the PAS Steam Tug Samson had variable Pitch propellors but I think He may be getting mixed up with the "Confiance" Class that did. Thanks all for your input. Last question when was it that VP or CPP Propellors were first introduced, how far do they go back in years?.


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## Stephen J. Card

Pielsticks = PielSTOPS!!!!!


A bit more on UTC STATESMAN. She was built in Japan (Kure) for Moran Towing, New York as ALICE L MORAN.

She came down to Bermuda for a stint on Salvage Station... 1966 I think. She arrived almost 24 hours late. She missed the island and had to turn around and find the way back. Not a good start!


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## skilly57

Derek,
Paxmans are still giving people nightmares! One of our Paxman 8RPHCZ models pulled down for survey over the last month - going back together, and, on torqueing down the last head, two studs pulled from the associated block. Fine threads into cast material - always a worry! Class now indicating we get a replacement block - for a 38-year old engine!
Why shouldn't I share my nightmare!

But, seeing as how this thread is about CPPs, I had better answer Tony's questions - my research shows that:

In 1870, Kamewa produced water turbines, then began experimenting with changing blade angles in these turbines.
In 1935, Liaaen developed the first controllable pitch propeller.
In 1937, the 1st Kamewa hydraulically controlled ship CPP was delivered.
In 1940, 20 Swedish minesweepers were fitted with Kamewa CPPs.
In 1948, the M/S Los Angeles was the 1st commercial application of a Kamewa CPP, at 7,000 hp per shaft
In 1949, Stone Manganese Marine produced their first CPP.

Cheers,
Tony


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## Duncan112

Does the Voith Schneider Propeller, first developed around 1926 and prototype installed in 1928 and in minesweepers 1929 count?


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## OLD STRAWBERRY

Thanks Skilly and All,
thats great. My questions answered.


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