History Question: Ahead 1/3rd?

[LoBlo]

Here's a question for those naval history buffs out there. Where do the terms ahead one-third, ahead two-third, ahead standard, ahead full, and ahead flank originate from? Meaning at which era and navy did they become commonly used terms? WWII? WWII? Pre-WWI?

A related question is: In a modern navy, do these terms still mean 5knots, 10knots, 15knots, 20knots, and 100% engine power respectively? (I remember playing 688 attack sub a while back and in that game 1/3rd = 8 knots, 2/3 = 16 knots, standard = 25 knots, full = 32knot, flank = 37knots)

[Bubblehead Nuke]

This was actually a qual question my Eng had for me when I was getting qualified for ERS. He had a funny sense of humor.

To understand the meaning you have to go WAY back to the beginnings of steam propulsion. Wayyyyy back then, the boilers were coal fired and it tood time for pressure to go up OR down. Materials were not as robust as they had now do they used steam pressure to control how fast a steam piston operated. The more pressure the faster it ran.

Anyway, the bells were to provide the engineman a standardized guide for operations. Ahead 1/3 would have been 1/3 the maximum normal pressure that the steam plant could produce. 2/3 was 2/3 and full was maximum pressure that it could substain during normal operations. They also had a bell they called maximum turns. It basically was the greatest amount of steam that the engineman thought that the boilers, pipes, and engines could bear. It was also called a 'Battle Bell' or 'Battle Speed'. You were limited by the intestinal fortitude of the engineman on duty.

Things progressed over time materials improved and the technology was more refined. You also had things like steam turbines instead of a reciprocating piston. Anyway, by now the boilers had shifted from a pressure control to a volumn control. They could use throttle valves to regulate the amount of steam going to the engines and auxillary gear. You also have a shifting from coal fired to some oil fired boilers so things could respond a lot quicker to changing situations.

Things like a standard and flank have now entered the vocabulary of the engineman. A Standard Bell is the most economical speed for a ship to move at. It is the greatest range at a given speed . Flank replaced the maximum bell and was a 100% effort of the engineering plant. The older Full Bell was now used to repesent a maximum speed the the FLEET could move at. Thus a full bell could vary depending on the on the vessels you are in convoy with.

Also, with boiler powered ships it was not economical to run all the boiler all the time. Thus, to conserve fuel, some boilers may be shut down and put on standby as a lesser number of boilers could still provide the neccesary steam volumn to drive the ship at the desired bell. When the engineroom is given the order 'make ready to answer all bells' they know that they need to get off their duffs and get the boilers all back online. When the engineroom is ready they would report back to the bridge ' Ready to answer all bells'

On that note, if you have ever watched any of the old wartime movies, you would hear something like: "#2 boiler is flooded, #3 boiler has popped a safety, #1 & #4 boilers are online. propulsion limit is ahead 2/3" during or after a battle. That was the engineroom telling the bridge what was going on and what kind of speed they can make. Later you might have heard, "repairs completed, propulsion limit ahead standard, flank upon request" That meant that all the boiler were not running at that time. They were only running enough boiler to meet the speed requirements at that time but that there was more available it needed.

1/3, 2/3, and standard now are typically a preset numer of revolutions on the screw or a given ships speed depending on the propulsion plant design. When the OOD gives the command for Ahead Standard he knows what the approximate speed the ship will go.

Please understand that this is all greatly simplified. There is so much that goes into steam plant operations that I could write reams of information. I hope this answers some of your questions

edited for spelling

[RedMenace]

Thats actually quite interesting.:D

[SeaQueen]

Please understand that this is all greatly simplified. There is so much that goes into steam plant operations that I could write reams of information. I hope this answers some of your questions

edited for spelling

That was really interesting. Are there any books you though were particularly good on the subject?

[JustJim]

Wow, A good question with a great answer.

Jim

[LoBlo]

You were limited by the intestinal fortitude of the engineman on duty.

:lol: That puts the engineer in quite a bind doesn't it. Whatever your running from is going to get you unless you go fast enough... but go *too* fast and you'll blow yourselves up with overstressing the engine. Quite a quandary

Great answer, Thanks! That was just what I was looking for.:up:

[Bubblehead Nuke]

That was really interesting. Are there any books you though were particularly good on the subject?

Unfortunately, this is not a topic for many historians. Operating procedures will vary from navy to navy and it is dependant on the quality of the equipment and the training of the engineering personnel.

The US Navy NavShipTech Manuals has a lot of this information. Some of it was gleaned from the history of the various boiler designs and how they were were operated. Boiler plant operation being a pretty standardized thing in the modern navy.

Being the pubs man for M Div I used my spare time to order a good many of the tech manuals. There is a TREMENDOUS amount of institutional information in them. Want to know the one I liked best?? Mothball layup up of ships for possible later reactivation. That book is a GOLDMINE of information on the older steam powered ships. It talks about how to operate the propulsion plant in various modes and then how to preseve it in a dry lay-up condition.

[Bubblehead Nuke]

:lol: That puts the engineer in quite a bind doesn't it. Whatever your running from is going to get you unless you go fast enough... but go *too* fast and you'll blow yourselves up with overstressing the engine. Quite a quandary

Great answer, Thanks! That was just what I was looking for.:up:

When the difference if getting sunk and killed or eeking that .3 knots out of the engine, you go for the gusto and roll the dice and hope you win.

Why do you think a GOOD engineer is ALWAYS in demand. Anyone can read a guage, but how many KNOW how the plant is operating by vibration, sounds, and even the SMELL of the plant while it is operating.

I will tell you, I could do that. I could walk throught the watertight hatch and go to ERML and by the sound tell you what was going on. Any good nuke could to that. When walking your watchstation you could feel the systems. It gets in your blood like nothing I can describe.

One time, we had a loss of the port non-vital switchboard, killed half the ship electrically. I was asleep in the rack when I woke up for no reason I can describe, I went from sleeping, opened my eyes, noticed no fan in my rack, and I was moving before I realized it. In my mind I am going: Fire, SCRAM, or something bad aft. I was offgoing engineering watch so my casualty station is aft. In fact, about 10 of us were moving aft within seconds BEFORE they even called away the problem. We did not even wonder what was going in. We KNEW something was wrong within about a second of each other. When I hit the mess deck I knew that the port SSTG had gone offline because of a panel on the mess deck. There are 2 lights on it, each powered by it respective bus, and the port powered light is off. I am already wondering if it is mechanical or electrical by the time I hit the hatch. I absorbed it by moving through the boat heading aft. No real thinking involved. As we hit the hatch control called away the loss of the port switchboard. Elapsed time: about 15 seconds. Oh, and the coners?? They didn't have a clue as to why so many of us had such a serious face on and a get the hell out of our way attitude till they called away the casualty.

See what I mean about getting in the blood?

A lot of the information about propulsion plant operations you will not find. It is just mumbo jumbo to those who never ran a plant and well, boring to those of us who have run one. The real JUICY parts, well, those are still classified.

On a slightly differnt note I would LOVE to sit down and create a mod that took into account propulsion plant operation in a tactical enviroment. Alas, that would get me a room in a prision. There are a LOT of things that go WAY beyond the scope of this sim but then again, it is operationally a constraint that the sub has to operate under and make decisions about. It is something that the captain of a ship HAS to be aware of and has a major input into how he does his job. Modeling it would put us at risk in the real world and thus I see the need to exclude it.

[Ultraboy]

I get the same feeling whenever someone touches the thermostat.





:lol:

[Sub Sailor]

This was an excellent explanation, and I especailly about sound and feel. I retired 1982, and I become so aware of the plant, I am a nuke also, that today if someting changes in my home I wake up.
I believe BN will agree with this, unknown noises drive you crazy, whether it is your car or what ever you got to find it.

BZ BuubbleHead,

Ron Banks MMCM(SS), USN(Ret)

[Respenus]

That was extremly interesting. Made quite a read. Makes you want to build a steam engine, put it on wheels or strap a propeler and away we go.

While I was reading the first part, the image of Scotty (Star Trek) telling Jim (Kpt. Kirk) the damage his engines took. I never saw TOS, but from what I saw from the movies and Relics (A TNG episode), he spoke like an old enginner. It also reminded me of another movie in which the enginner talked like that, but I can't remember the name (some sci-fi movie).