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SEA TRIALS 23 years 2 months ago #15066

  • wilsonle
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Marc, Actually you would be surprised to learn that our bow mounted sonar actually reduced our drag. If you ever see a super tanker riding high you will see a bulbous bow (it looks suspiciously like a sonar dome)but its intent is to lower the ships drag through the water.
Also glover had 2 1200lb prsseure fired boilers and put out 35,000 shaft horsepower on one screw/pumjet against her displacement of 3100 (approx) tons.
Cochrane had 4 boilers and made 70,000 horsepower on 2 screws against a displacement of 4500 (approx) tons.
So Cochrane had Glover beat on power to weight, and effective propeller surface area.
Glover I think was rated at 27 knots design and Cochrane (Adams) design was 32. Power requirement rises exponentially at around 25 knots in destroyers. So doubling power does not buy you a lot.
This is all published shit (unclass) but based on my slide rule I would say a true 37 and possible 42 is within the realm of possibility, if she was light load (no weapons aboard, or reduced weapons and fuel load)

FTG1(SW)DDG-21 80-84 NRFF-1091 USS Miller 85-87

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SEA TRIALS 23 years 2 months ago #15067

  • Ken Keeler
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Pat and Larry,
The Cochrane on sea trial just off the straits of Juan de Fuca did in fact do 42 KTS. no stores, no ammop, no missles and as I rember only about half a load of fuel. The ship did in fact go from all ahead flank to all back emergency and was dead in the water in about one and a half to two ship lengths. The stern of the ship was literally buried under water, almost 1/2 way up the bulworks to the 01 deck. it was one hell of a sight.
the ship for the next year routinely did 35kts with full load outs and we did hit 37kts. a couple of times but that was only in long distance runs. The DD752 that I was on which also only had 600lb steam many times did 32kts. and could usually sustain 30 plus with ease.
They built those ship very tough, definately to go in Harms way. I guess that is why it takes so much to sink them when they used them for targets.

Ken Keeler QM2 63-65

Edited by - Ken Keeler on 07/10/2001 14:23:11

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SEA TRIALS 23 years 2 months ago #15068

  • Ken Keeler
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I also forgot to add that that was using what as I remember as NSFO (Naval Standard Fuel Oil) which was not the same as the Distlate, has a great deal more BTU's but it can also be broken down by cat crackeing in the refinery to produce more top end fuels(Gasoline, Diesel, Kero etc) This is where the distlate came from, it is actually a recombined fuel with a lot less BTU's.
It is like trying to fire a steam locomotive on diesel fuel. takes a lot to produce a little steam. ( Burning waste motor oil has a lot more BTU's)

Ken Keeler QM2 63-65

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SEA TRIALS 23 years 2 months ago #15073

  • wilsonle
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Thats great, I am a self taught naval engineer, so my slide rule was right. 42 light load came out as the upper end for that hull planform. I did not however take into account the difference in Navy Standard and DFM as per BTU potential. (That 32Knots is what the designers published as its full load displacement full power design speed, design speed is just a guess ,SWAG, by the Naval Architects at the time the design is committed to paper)

FTG1(SW)DDG-21 80-84 NRFF-1091 USS Miller 85-87

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SEA TRIALS 23 years 2 months ago #15075

  • Marc Tuton
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Thanks, Larry! Im impressed with your vast knowledge in this area, and self taught also? A big tip of the hat, sir!

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SEA TRIALS 23 years 2 months ago #15083

  • wilsonle
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Actually, speed is a "mostly" a function of hydrodynamic efficiency (hull planform, parisitic drag etc.) and shaft horsepower. I am unaware if the switch to DFM lowered our SHP from the original 70,000. Maybe Chief Engineer Freeman knows.

FTG1(SW)DDG-21 80-84 NRFF-1091 USS Miller 85-87

Edited by - wilsonle on 07/12/2001 09:57:32

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