Special abilities question

[Sailor Steve]

Originally Posted by Bubblehead1980

The only special ability I use is the officer can allow extra surface speed bc it is realistic(well the ability not having one man who can allow it) I have read several books where the skippers allowed operation of engines beyond safety limits for period of time when extra boost was needed.Barb did this under Fluckey, believe Tang did it as well as Seahorse at one point.Barb was making 23 knots for a time.

Please post links or give full references. The diesel engines did not drive the propellors directly, but ran the generators that drove the electric motors that drove the propellors. Also, the law of diminishing returns applies. In other words, the South Dakota class battleships made 27 knots on 130,000 horsepower, and the Iowas used almost twice that to gain an extra five knots. To make an American fleet boat go 23 knots would require adding at least 20% more horsepower, and I don't see where anybody short of Gandalf the White would get that from.
http://en.wikipedia.org/wiki/List_of...ed_States_Navy
http://www.uboat.net/allies/warships...ype=Battleship

I'm not saying it couldn't happen, I'm just saying that any skipper's claims have to be suspect in the light of engineering limitations.

http://www.navweaps.com/index_tech/tech-003.htm
http://www.navweaps.com/index_tech/tech-029.htm
http://www.navweaps.com/index_tech/tech-028.htm
http://www.navweaps.com/index_tech/tech-095.htm
http://www.navweaps.com/index_tech/tech-104.htm

The above tables are all for battleships and aircraft carriers, but the principle is the same for any vehicle. If you have a car that goes 100 mph on 100 hp, doubling the horsepower to 200 will only get you up to about 150 mph. Doubling it again to 400 hp will only give half as much again, or 175 mph. doubling it again to 800 hp will get you to 187 mph. Of course changing the gearing can gain you a little speed in exchange for reduced acceleration, but even in the days of 1000 horspower twin turbocharging grand prix cars barely made 200 mph. If a sub is going 21 knots on 5400 horsepower dredging up another 20 or 50 hp won't make any difference, and I don't know where they'd find another thousand.

[edit] As for the anecdotal claims, the only thing they had to go on was the tachometer. The only way to measure a ship's real speed is in a timed trial between two points measured from land, and that is done under controlled conditions. Did any timed trials ever get a Gato past the claimed 20.25 knots?

[commandosolo2009]

Originally Posted by Sailor Steve

Please post links or give full references. The diesel engines did not drive the propellors directly, but ran the generators that drove the electric motors that drove the propellors. Also, the law of diminishing returns applies. In other words, the South Dakota class battleships made 27 knots on 130,000 horsepower, and the Iowas used almost twice that to gain an extra five knots. To make an American fleet boat go 23 knots would require adding at least 20% more horsepower, and I don't see where anybody short of Gandalf the White would get that from.
http://en.wikipedia.org/wiki/List_of...ed_States_Navy
http://www.uboat.net/allies/warships...ype=Battleship

I'm not saying it couldn't happen, I'm just saying that any skipper's claims have to be suspect in the light of engineering limitations.

http://www.navweaps.com/index_tech/tech-003.htm
http://www.navweaps.com/index_tech/tech-029.htm
http://www.navweaps.com/index_tech/tech-028.htm
http://www.navweaps.com/index_tech/tech-095.htm
http://www.navweaps.com/index_tech/tech-104.htm

The above tables are all for battleships and aircraft carriers, but the principle is the same for any vehicle. If you have a car that goes 100 mph on 100 hp, doubling the horsepower to 200 will only get you up to about 150 mph. Doubling it again to 400 hp will only give half as much again, or 175 mph. doubling it again to 800 hp will get you to 187 mph. Of course changing the gearing can gain you a little speed in exchange for reduced acceleration, but even in the days of 1000 horspower twin turbocharging grand prix cars barely made 200 mph. If a sub is going 21 knots on 5400 horsepower dredging up another 20 or 50 hp won't make any difference, and I don't know where they'd find another thousand.

[edit] As for the anecdotal claims, the only thing they had to go on was the tachometer. The only way to measure a ship's real speed is in a timed trial between two points measured from land, and that is done under controlled conditions. Did any timed trials ever get a Gato past the claimed 20.25 knots?

Just a confirmation: If the tachometer measured surface propulsion, the bendix log measured ...............? Fill in the blanks. No joke, seriously.

[Sailor Steve]

Originally Posted by commandosolo2009

Just a confirmation: If the tachometer measured surface propulsion, the bendix log measured ...............? Fill in the blanks. No joke, seriously.

Maybe you should fill in the blanks for me. The tachometer is no more accurate for measuring ship speed than the pitot tube is for measuring aircraft speed. There were P-47 pilots who claimed they broke the sound barrier in a dive. That's how 'accurate' they are. A shipboard tachometer doesn't have direct contact to the surface medium like a car's does. It can't account for propellor slippage or cavitation.

I'm not saying it didn't happen. What I'm saying is that I have 35 years experience playing tabletop wargames with 'gamers' who want every advantage, and their justification is always the same: "I read it in a book somewhere".

[TorpX]

Originally Posted by Sailor Steve

Maybe you should fill in the blanks for me. The tachometer is no more accurate for measuring ship speed than the pitot tube is for measuring aircraft speed. There were P-47 pilots who claimed they broke the sound barrier in a dive. That's how 'accurate' they are. A shipboard tachometer doesn't have direct contact to the surface medium like a car's does. It can't account for propellor slippage or cavitation.

I'm not saying it didn't happen. What I'm saying is that I have 35 years experience playing tabletop wargames with 'gamers' who want every advantage, and their justification is always the same: "I read it in a book somewhere".

I've read the same thing that Eric did. I believe it was in O'Kane's CLEAR THE BRIDGE. His claims would be based on the speed incicated by the Bendix log. I don't know what you refer to when you use the term tachometer. While the Bendix log would not be as accurate as a timed trial, great care was taken to calibrate it for accurate results. If it had not been accurate, the firing solutions genarated by the TDC, would not have been sound.

Did any timed trials ever get a Gato past the claimed 20.25 knots?

Perhaps not, but there are more variables here in a Gato or any sub, than with a battleship. Current displacement, and charge on the battery would affect this. Do timed trials usually involve pushing engines beyond their design limits?

Of course you are free to accept whatever sources you choose, but I am inclined to take O'Kane's word for it, as he has spent more time in fleetboats than I.

[Sailor Steve]

Originally Posted by TorpX

I don't know what you refer to when you use the term tachometer.

It's a device that counts engine revolutions. You can judge your speed by the revolutions. Unfortunately the problems I mentioned earlier make it less accurate the faster you travel

While the Bendix log would not be as accurate as a timed trial, great care was taken to calibrate it for accurate results. If it had not been accurate, the firing solutions genarated by the TDC, would not have been sound.

I see. I apologize for being unfamiliar with the instrument, but a careful study here brought me up to date.
http://www.maritime.org/fleetsub/log/index.htm

The first thing I notice is that it operates on a similar principle to the pitot tube. This may affect accuracy at high speeds, or it may not. As I said, I'm not saying it didn't happen, just listing the reasons why I tend to question it.

Perhaps not, but there are more variables here in a Gato or any sub, than with a battleship. Current displacement, and charge on the battery would affect this. Do timed trials usually involve pushing engines beyond their design limits?

No, the variables are the same. Any ship trial is conducted with as light a load as possible, and as much power as possible, the goal being to make the ship look as good as possible to the potential buyer (in this case of course the navy). In the case of a submarine it would require the batteries be fully charged of course, and the engines are pushed absolutely as fast as they'll go. With that in mind I would insist that 20.25 knots was the best speed on the best day, maybe getting to 21 if you're lucky.

Of course you are free to accept whatever sources you choose, but I am inclined to take O'Kane's word for it, as he has spent more time in fleetboats than I.

And that's the crux of the matter. On the one hand anecdotal evidence is always suspect, especially given possible variations in measuring equipment. On the other hand anecdotal evidence is vital because sometimes it really is true.

On the other other hand I don't lie and I don't cheat, so when I find something that supports an opposing argument I don't sweep it under the rug. I tracked down Bubblehead1980's mention of Fluckey and Barb, and sure enough he not only claimed to have made 23.5 knots using "150% overload", however that works with a diesel engine, but was officially credited with a world speed record for it.
http://en.wikipedia.org/wiki/Eugene_B._Fluckey

Again, I'm no engineer, but I do have a basic understanding of how these things work, and while Bubblehead "has no doubt" that it happened, I still do. But you have your statements from the people who were there, and I can't dispute their claims. I can, however, question the equipment, but I can't prove it. You talked about the accuracy during an attack, but an attack takes place at 2 knots, not 20. Are the instruments accurate at higher speeds? Car speedometers and aircraft air speed indicators are not.

So it's an impasse. But I will leave you with one question: If it's realistic to allow the special ability to boost the speed that much, is it still realistic to not have any chance of an engine breakdown at the worst possible moment? To my mind you can't have one without the other and still claim realism.

[TorpX]

No, the variables are the same. Any ship trial is conducted with as light a load as possible, and as much power as possible, the goal being to make the ship look as good as possible to the potential buyer (in this case of course the navy). In the case of a submarine it would require the batteries be fully charged of course, and the engines are pushed absolutely as fast as they'll go. With that in mind I would insist that 20.25 knots was the best speed on the best day, maybe getting to 21 if you're lucky.

You may be right, but it is still hard for me to believe they would push engines far past their limits in peacetime trials. Or maybe the boats became lighter during refits?

...claimed to have made 23.5 knots using "150% overload", however that works with a diesel engine, but was officially credited with a world speed record for it.

I don't know enough about this sort of thing to even guess. 150% does sound incredible.

You talked about the accuracy during an attack, but an attack takes place at 2 knots, not 20. Are the instruments accurate at higher speeds?

I skimmed through the manual for the Bendix log. I didn't see any standard for accuracy, but they did calibrate them at 2 speeds minimum (low and high) and at as many as possible, time permitting. They had to be good not just during a submerged attack, but throughout an approach, surfaced or submerged. The maintainace/ calibration proceedures were very involved. They were obviously considered important.

And that's the crux of the matter. On the one hand anecdotal evidence is always suspect, especially given possible variations in measuring equipment. On the other hand anecdotal evidence is vital because sometimes it really is true.

Agree.

So it's an impasse. But I will leave you with one question: If it's realistic to allow the special ability to boost the speed that much, is it still realistic to not have any chance of an engine breakdown at the worst possible moment? To my mind you can't have one without the other and still claim realism.

I agree completely. The magic-engines that never break down is a weak point in the game. So is the rocket-like acceleration of everything. What is the speed advantage of the special abilities anyway? I had assumed it was a mod-dependent thing. I've never had it in the game, so I never gave it much thought before.

[Sailor Steve]

I think we're agreed that we don't have a definitive answer, and may never. The only thing I'm still insisting on at this point is the trials. For surface ships they really did pull out all the stops, running with no ammunition, no stores, minimum crew and fuel, and gave it everything they had. In the early days of destroyers (British, 1892), when they were coal-fired, they actually doubled the shovellers, working them in two shifts, ten minutes at a time, so they were shovelling their absolute hardest all the time.

Unfortunately I haven't been able to find any official trial data for any submarines. I suspect they didn't run speed trials because nobody cared if they could reach their designed speeds. After all, no sub is going to outrun a destroyer (pre-nuke of course).