# Rpm



## A.D.FROST (Sep 1, 2008)

Hands up how many engineers (Juniors) have worked out the revs before the end of the watch and found a few revs out and helped the counter (Dofords/B&W) to catch up.I done it once and all the number cogs fell out (Whoops!) it was like rebuilding the enigma machine.(EEK)


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## AlbieR (May 18, 2007)

I had one Welsh junior where the counter passed 999999 and went to zero, it took him 2 hours to work out the RPM! I do believe he made Chief in the end, the mind boggles.


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## A.D.FROST (Sep 1, 2008)

AlbieR said:


> I had one Welsh junior where the counter passed 999999 and went to zero, it took him 2 hours to work out the RPM! I do believe he made Chief in the end, the mind boggles.


Wasn't that worth a case of beer?(Pint)


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## Engine Serang (Oct 15, 2012)

I made Chief in the end and never fully understood why I couldn't work out the slip on a CPP.


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## doxfordsix (Apr 2, 2012)

The Doxford six did a consistent 104 rpm on voyage. Any variation more than 0.1 prompted questions. A Prince Line ship could not make anything like normal revs without overheating. It stopped to investigate and a dead whale detached itself from under the bow!


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## cacique (Mar 26, 2005)

Working out the rpm at ten minutes to the end of the watch, can still remember my 230 times table !

Cacique


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## Tony Morris (Oct 7, 2006)

While with UASC I made a table in a note book to make the calculation easier and did the calculation 10 mins before the end of the watch. I always seemed to be on the 12 -4 and when with Capt Parry phoned down after lunch every day to increase/decrease 0.1 rpm we said yes sir and did nowt. He never complained.


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## John Paul (May 27, 2007)

pinched a few off the 12/4 watch at midday a few times but no one said anything and gave a few away if the weather was a bit rough, still ended up in port so no harm done mind you 40 odd years ago now,no one to moan now


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## A.D.FROST (Sep 1, 2008)

Tony Morris said:


> While with UASC I made a table in a note book to make the calculation easier and did the calculation 10 mins before the end of the watch. I always seemed to be on the 12 -4 and when with Capt Parry phoned down after lunch every day to increase/decrease 0.1 rpm we said yes sir and did nowt. He never complained.


Normally that kind of suggestion comes from a some-one from a steam ship.I was on RN pretend war convoy and we had on board a RN commander(pain in the R'z) every 5mins asking for a increase/decrease by 1 or 2 rev's and like you the answer was yes/OK trouble was you couldn't move from the sticks and got writer cramp filling in the movement book.(Scribe)


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## ianrobson36 (Dec 9, 2012)

you could work out the revs, can you remember how to work out the slip. because I can't, must be old age

Gingerbeer


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## Engine Serang (Oct 15, 2012)

Have a Cadet on Watch with you.


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## A.D.FROST (Sep 1, 2008)

Engine Serang said:


> Have a Cadet on Watch with you.


Our company didn't employ cadets that could count other wise they would ask for money.What do you call a cadet that can count...Hand(Y)because he had all his fingers and toes.[=P]


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## spongebob (Dec 11, 2007)

Can barely remember what we did but so many times when we were heading for home into head seas on a fully laden Piss Poor Polar Powered collier the revs were aplenty but the distance travelled wasn't worth mentioning.

Bob


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## sternchallis (Nov 15, 2015)

A.D.FROST said:


> Wasn't that worth a case of beer?(Pint)


Yes, with the same company the counter was about to turn over and nobody wanted to buy the case of beer, so between the 12/4 and the 4/8 they would either pull the job back a notch or increase a notch to make sure it didn't fall on their watch. The Chief was an old Scotsman, I wonder if he ever queried why the average rpm was so up and down on those watches at night. Not sure who caught it.

As a first trip jnr, they tried to get me for a case of beer crossing the line (which I put on under sufference) but also crossing the International Date Line, first foreign port in Kiwi, but didn't bite for those. We had been round North Sea ports loading and passed through Panama but no mention of a case then.

On an old twin Doxford I decided to take some cards, one engine the counter packed up and the other the tacho was jumping about. The Chief said 'Don't bother'. But I took them all the same and used the same rpm for both. Tracing a line on a 2"x3" diagram is hardly accurate, but we all did it.


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## kauvaka (Oct 11, 2009)

Still on revs. this time critical ones. I was a F/G On the British Valour and the Br Aviator watch keeping in the boiler rooms, cushy job because the burners were only pulled and cleaned once a week deepsea. When maneuvering though it was all on at the boiler front and the engine revs moved through a period of "critical revs" when the ship would vibrate like a NZ earthquake and asbestos dust would fall like snow from the lagging. My memory is there was a telegraph-like rev counter thing down on the E/R plates and the critical revs area was shown in red. Is my memory correct on that? I was on other ships, steam and motor including the RFA Wave Sovereign (steam job) and during RAS the telegraph slave counter on the boiler flat would instruct "up 2 revs' then "down 5 revs' and so on but I can't recall a "critical rev" phase. Was there one? Did all engines have this phase?


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## oldgoat1947 (Apr 5, 2018)

Critical Revs depends on many factors. No of Prop blades, Diameter and length of Prop Shaft. Some of the Modern slow speed Diesels with Odd Number of blades do not have a critical range.


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## Clifford Cocker (Jan 21, 2008)

*Critical Speeds*

In the 50s when all the Panama Pilots were American, they would ask for "up 5" or similar, we used to tell them that we couldn't "it was too close to our critical speeds (LB Doxfords) they were not happy with the Port Wellington on my second voyage on her, after all the bearing problems we were limited by Lloyds to 90 rpm on the Starboard Engine,
the QMs were not happy either out at sea with mismatched revs.


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## sternchallis (Nov 15, 2015)

Clifford Cocker said:


> In the 50s when all the Panama Pilots were American, they would ask for "up 5" or similar, we used to tell them that we couldn't "it was too close to our critical speeds (LB Doxfords) they were not happy with the Port Wellington on my second voyage on her, after all the bearing problems we were limited by Lloyds to 90 rpm on the Starboard Engine,
> the QMs were not happy either out at sea with mismatched revs.


With Blue Star we had the Wellington Star, twin 6 LB's, whilst in the Caribean a top piston came out on the Port engine, so we had a 6 and a 5 then to go through Panama, so plenty of Stb helm to keep her straight as the Port was on reduced revs.
Homeward bound the siderod crosshead came out. 
Blow by blow account elswhere on the forum.


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