Bismarck speed during last battle
Moderator: Bill Jurens
Re: BS speed - last battle
Wow, congratulations!
Re: BS speed - last battle
Congratulations Bill.
Hope everything goes well for you both.
It's funny, but I too have been looking at Bismarck's draught at Norway and she looks pretty full to me too. It would make sense to have the reserve bouyancy filled with fuel, because it would be burned off by the time enemy forces were encountered and the trim tanks could once again be used.
All the best
Vic
Hope everything goes well for you both.
It's funny, but I too have been looking at Bismarck's draught at Norway and she looks pretty full to me too. It would make sense to have the reserve bouyancy filled with fuel, because it would be burned off by the time enemy forces were encountered and the trim tanks could once again be used.
All the best
Vic
Re: BS speed - last battle
Yes, congratulations Bill!
Axis BBs gives a summary of Bismarck's fuel state. On May 18, 0700 she took on 8100 tons, of which 7800 tons were usable. Upon departing Norway on May 21 about 1400 tons were burned By May 22, they estimated that Bismarck had burned about 2000 tons of fuel, and another 1150 tons by 0600 May 24. Fueling in Norway could have given Bismarck about 1500 additional tons of fuel.
Based upon trials data from Richelieu, Vanguard and VV , I would estimate (again crudely) that Bismarck's maximum speed at full load displacement would be about 28 knots, but I would (again crudely) estimate that Bismarck would gain about .3 knots per thousand tons of fuel burned, so having burned ~3000 tons of fuel, Bismarck would have gained about .9 knots by the time she encountered Hood.
The KM were probably aware that Hood and KGV both had maximum speeds of ~29 knots, so with fuel burn Bismarck's maximum speed by the time she was likely to encounter RN heavy units, would have been a close match for the RN's fast BBs.
Axis BBs gives a summary of Bismarck's fuel state. On May 18, 0700 she took on 8100 tons, of which 7800 tons were usable. Upon departing Norway on May 21 about 1400 tons were burned By May 22, they estimated that Bismarck had burned about 2000 tons of fuel, and another 1150 tons by 0600 May 24. Fueling in Norway could have given Bismarck about 1500 additional tons of fuel.
Based upon trials data from Richelieu, Vanguard and VV , I would estimate (again crudely) that Bismarck's maximum speed at full load displacement would be about 28 knots, but I would (again crudely) estimate that Bismarck would gain about .3 knots per thousand tons of fuel burned, so having burned ~3000 tons of fuel, Bismarck would have gained about .9 knots by the time she encountered Hood.
The KM were probably aware that Hood and KGV both had maximum speeds of ~29 knots, so with fuel burn Bismarck's maximum speed by the time she was likely to encounter RN heavy units, would have been a close match for the RN's fast BBs.
Re: BS speed - last battle
HI Dunmunro.
I would not expect Bismarck's speed to be less than 30 knots whatever load she was carrying, her immersion for 1500 tons was just 1 foot (30.5cm). So if she sailed with her bunkers half empty she would only draw 2ft 8in less, a saving of 0.8 metres.
At full load I would expect her not to be able to make her maximum speed attained on trials of 30.8 knots, unless overdriven - a capability which all steam driven ships have. Then she might make 31 to 32 knots, depending on sea temperature, though not without expending fuel at 3 to 4 times her cruising rate.
Bismarck sailed with a clean bottom, and she will have been able to make 30 knots, though at a burn-rate of about 100 tons per hour. The squadron is logged as having gone onto 30 knots for an hour on the night of the 23rd.
I think it is likely that Bismarck's fuel stocks are estimated from her normal capacity of 8300 tons, less that which could not be taken aboard due to the ruptured hose. If the ship had filled her trim tanks as well, this may make for an additional amount which no one has been yet able to calculate.
My own calculation - extrapolated from a comparison with PG's consumption - amounts to 3500 tons, consumed by 1700 on the 24th, leaving 4600 tons, by the estimate on sailing of 8100 tons. We can allow 1000 tons to have been lost due to enemy action earlier that day and the ship still has 3600 tons left. That is more than enough to get her all the way back to Danzig
She could steam for 72 hours at 28 knots - her maximum after the shell damage to the bow, or remain at sea for 6 days steaming at 22 knots, though if she was to remain at sea, there would be no reason to keep up even this speed.
At the time Bismarck put into Bergen she had consumed no more than 850 tons about 10% and it would hardly be worth bringing the tanker in to top up that small amount, especially if it was thought the impression could be given to watchers on the shore that no sortie was planned for the near future. Refuelling would rub out that doubt.
Finally, had there been any doubt about Bismarck's fuel stocks, Lutjens would have kept her at sea and awaited an opportunity to bunker after PG had finished with the tanker. The ship could have stooged around at 10 to 15 knots and would have been able to remain at sea for 2 weeks. The heat would have died down and the refuelling could have proceeded without worry.
Clearly the stategic advantage of getting the ship into the dockyard and repaired ready for her next operation over-rode the question of risk to the ship. That was a chance which Lutjens took on his own authority and which proved to be his downfall, though the likelihood of the ship being stopped by a single torpedo was very slim.
Lutjens could have kept PG under his close orders and with the flagship disabled and needing repair, could have reasonably transferred his flag so as to remain fully mobile and wouldn't the anti-Lutjens mob have had a field-day over that!
Regards Vic
I would not expect Bismarck's speed to be less than 30 knots whatever load she was carrying, her immersion for 1500 tons was just 1 foot (30.5cm). So if she sailed with her bunkers half empty she would only draw 2ft 8in less, a saving of 0.8 metres.
At full load I would expect her not to be able to make her maximum speed attained on trials of 30.8 knots, unless overdriven - a capability which all steam driven ships have. Then she might make 31 to 32 knots, depending on sea temperature, though not without expending fuel at 3 to 4 times her cruising rate.
Bismarck sailed with a clean bottom, and she will have been able to make 30 knots, though at a burn-rate of about 100 tons per hour. The squadron is logged as having gone onto 30 knots for an hour on the night of the 23rd.
I think it is likely that Bismarck's fuel stocks are estimated from her normal capacity of 8300 tons, less that which could not be taken aboard due to the ruptured hose. If the ship had filled her trim tanks as well, this may make for an additional amount which no one has been yet able to calculate.
My own calculation - extrapolated from a comparison with PG's consumption - amounts to 3500 tons, consumed by 1700 on the 24th, leaving 4600 tons, by the estimate on sailing of 8100 tons. We can allow 1000 tons to have been lost due to enemy action earlier that day and the ship still has 3600 tons left. That is more than enough to get her all the way back to Danzig
She could steam for 72 hours at 28 knots - her maximum after the shell damage to the bow, or remain at sea for 6 days steaming at 22 knots, though if she was to remain at sea, there would be no reason to keep up even this speed.
At the time Bismarck put into Bergen she had consumed no more than 850 tons about 10% and it would hardly be worth bringing the tanker in to top up that small amount, especially if it was thought the impression could be given to watchers on the shore that no sortie was planned for the near future. Refuelling would rub out that doubt.
Finally, had there been any doubt about Bismarck's fuel stocks, Lutjens would have kept her at sea and awaited an opportunity to bunker after PG had finished with the tanker. The ship could have stooged around at 10 to 15 knots and would have been able to remain at sea for 2 weeks. The heat would have died down and the refuelling could have proceeded without worry.
Clearly the stategic advantage of getting the ship into the dockyard and repaired ready for her next operation over-rode the question of risk to the ship. That was a chance which Lutjens took on his own authority and which proved to be his downfall, though the likelihood of the ship being stopped by a single torpedo was very slim.
Lutjens could have kept PG under his close orders and with the flagship disabled and needing repair, could have reasonably transferred his flag so as to remain fully mobile and wouldn't the anti-Lutjens mob have had a field-day over that!
Regards Vic
Re: BS speed - last battle
When did Bismarck ever achieve 30.8kn at her trials? (this figure is frm TP not from BS, the one from BS is 30.1kn IIRC) This figure is extrapolated and was never achieved. At her trials she made 28.374kn at 117k hp which was neither at maximum displacement nor at maximum hp with a clean hull and without the rougher paint she got later. Her max HP were 150k at overload her normal maximum was 138k hp, which makes the 30.8kn highly unlikely at maximum load and with the later paint. 29kn.x maybe even 30kn (but I doubt 30kn) was the most you could expect at maximum load and 150k HP.
31-32kn are pure fantasy unless BS could somehow increase her max HP by some 50k which she was not able to.
Her trial data:
A Messprotokoll from 29.10.40 gave the following results:
Water depth 65 m
payload 75%
port shaft 38753 shp at 251,7 rpm
middle shaft 38820 shp at 244,1 rpm
starbord shaft 39837 shp at 252,7 rpm
maximum speed for that day was 28,374 knots.
And congratulations Bill!
31-32kn are pure fantasy unless BS could somehow increase her max HP by some 50k which she was not able to.
Her trial data:
A Messprotokoll from 29.10.40 gave the following results:
Water depth 65 m
payload 75%
port shaft 38753 shp at 251,7 rpm
middle shaft 38820 shp at 244,1 rpm
starbord shaft 39837 shp at 252,7 rpm
maximum speed for that day was 28,374 knots.
And congratulations Bill!
Re: BS speed - last battle
Will someone please explain to me what "overload" is and how one achieves it? On a submarine you have 50% reactor power, which produces enough steam to go a certain speed (we called it "ahead full"), and 100% reactor power, which gives you a few knots more, and we called that "flank speed". I can't imagine going faster than you have steam to put in the turbines, and that would be your maximum speed, which would vary with displacement. How do you "overload" this?
Re: BS speed - last battle
May I point out, that Bismarck's trials and performance measurements were made in the Baltic Sea--a fact that many fail to understand the implications of, but which has since been dealt with by knowledgeable sources in the intervening years. Seems the Baltic was quite favorable to the skewing of German-stated displacement figures. Speeds are absolute, measurable against fixed points (such as the Royal Navy's measured mile at Arran), but wouldn't Bismarck's speed be affected, even by a few percentage points, when steaming in waters outside the Baltic, with its unusual specific gravity.
How might the shift in environments to North Atlantic waters, have altered her actual fuel-consumption and speeds?
(Or, is this too small an effect to factor into such calculations?)
Just a thought.....
How might the shift in environments to North Atlantic waters, have altered her actual fuel-consumption and speeds?
(Or, is this too small an effect to factor into such calculations?)
Just a thought.....
Re: BS speed - last battle
Overload can mean several things. On your sub, max reactor heat output may have equaled 100% of available power, and no more was possible, but if we assume that the reactor could produce more heat and thus steam pressure, than the max continuous pressure and volume rating of the steam system, then you would have an "overload".Bgile wrote:Will someone please explain to me what "overload" is and how one achieves it? On a submarine you have 50% reactor power, which produces enough steam to go a certain speed (we called it "ahead full"), and 100% reactor power, which gives you a few knots more, and we called that "flank speed". I can't imagine going faster than you have steam to put in the turbines, and that would be your maximum speed, which would vary with displacement. How do you "overload" this?
On the KGV class the (and typical for RN ships) full power trials were run at the 100% continuous rating of the boilers, but the steam system was designed to accept short term overloads in steam pressure and volume(I've read that the RN typically allowed for an additional 'safe' 25% power (via increased steam pressure and volume), above the trials figures - however some navies ran trials at the absolute max safe limits). By increasing the fuel burn in the boilers and increasing the air intake via the boiler room intake fans, the boilers could be forced to produce steam pressures and volumes considerably above the continuous safe rate for the steam system. Hence, PoW ran trials at ~112k SHP but during the run to intercept Lutjens she produced 134K SHP. On a forced draft boiler, overload is thus achieved through a combination of increasing air pressure and increases in fuel supplied to the boiler. On a non forced draft boiler, the increase would be done by increasing the fuel burn. Increasing the steam pressure and volume would be limited by the availability of reserve feed water, the probability of failure in the steam pressure vessel, and turbine damage and finally by the maximum capacity of the fuel system to supply enough oil to the boilers. The KGV's boilers each had 9 fuel sprayers, each capable of supplying 1500lb of oil/hour, so the maximum possible power input of the system would equal 1500lb x 9 x 8 (boilers) = 108,000lb of fuel or 48.2 tons/hour. Maximum output would depend on the specific power output rating of the system. If KGV maintained the same specific output as Warspite after her rebuild in 1937, her specific consumption would equal .745 lb/SHP and she could achieve a maximum 145K SHP. However the specific consumption might increase due to increasing inefficiency in the combustion/steam cycle, so the max power might fall to 135K SHP with a figure of .8 lb/shp.
For reference HMS Howe was measured to burn 36 tons/hour at 27 knots and 40 tons/hour at 28 knots (temperate water clean bottom), no displacement was given but I suspect these figures were at something like 44000 tons displacement.
In a single reactor sub, it doesn't make sense to have the reactor capable of supplying more steam than the pressure vessel could accept safely, but in a dual reactor boat, I'll bet that each reactor was capable of supplying an overload, which would help the boat maintain speed in the event that one reactor was shut down or limited in power output, for some reason.
Last edited by dunmunro on Sat Aug 02, 2008 8:48 pm, edited 1 time in total.
Re: BS speed - last battle
In all naval machinery and equipment, there was a normal working load and an emergency over load condition.
The Admiralty turbines fitted in the KGV class had a normal maximum output of 100.000 shp, giving a maximum speed of 28.5 knots at standard displacement and 27.5 knots at full load. In emergencies this could be extended to 110,000 shp, giving 29.5 knots at standard displacement and 28.5 at full load.
In a dire emergency, this could be extended even further for a short time and I believe the captain would signal this to his engineers by putting the telegraph to full-ahead three times.
Of course added shp and shaft revolutions do not make for a specific increase in speed, since hull=form imposes it's own limits on a vessel's speed and every class of ship is different. A foul bottom can drastically reduce speed also.
Sea temperature also plays it's part in governing ship's speed. Cold water will make the condensers work more efficiently causing a greater differential between the pressure and the vacuum ends of the turbine, making it behave as if greater steam pressure had been applied. Warm water will reduce this efficiency and in turn reduce speed.
The KGVs were much smaller ships than the Bismarck class and had an immersion of 1 foot for 1300 tons as compared to Bismarck's of 1 foot for 1600 tons. This means that the difference between the standard and the full load displacment condition would cause a 25% greater draught increase in the KGVs than in the Bismarck class and a proportionately greater loss of speed.
Bismarck's hull form produced a greater waterline length than the KGVs and will have permitted a higher speed, so the reduction in speed at full load will be less in Bismarck also. So where a 1 knot differential in speed is calculated for the KGVs between full and standard displacement, only about half a knot reduction will apply to Bismarck, due to her larger hull.
Bismarck will have completed speed trials and though the figures may be disputed the ship is logged has having made 30 knots for a short period during the passage through the Denmark Strait.
Vic
The Admiralty turbines fitted in the KGV class had a normal maximum output of 100.000 shp, giving a maximum speed of 28.5 knots at standard displacement and 27.5 knots at full load. In emergencies this could be extended to 110,000 shp, giving 29.5 knots at standard displacement and 28.5 at full load.
In a dire emergency, this could be extended even further for a short time and I believe the captain would signal this to his engineers by putting the telegraph to full-ahead three times.
Of course added shp and shaft revolutions do not make for a specific increase in speed, since hull=form imposes it's own limits on a vessel's speed and every class of ship is different. A foul bottom can drastically reduce speed also.
Sea temperature also plays it's part in governing ship's speed. Cold water will make the condensers work more efficiently causing a greater differential between the pressure and the vacuum ends of the turbine, making it behave as if greater steam pressure had been applied. Warm water will reduce this efficiency and in turn reduce speed.
The KGVs were much smaller ships than the Bismarck class and had an immersion of 1 foot for 1300 tons as compared to Bismarck's of 1 foot for 1600 tons. This means that the difference between the standard and the full load displacment condition would cause a 25% greater draught increase in the KGVs than in the Bismarck class and a proportionately greater loss of speed.
Bismarck's hull form produced a greater waterline length than the KGVs and will have permitted a higher speed, so the reduction in speed at full load will be less in Bismarck also. So where a 1 knot differential in speed is calculated for the KGVs between full and standard displacement, only about half a knot reduction will apply to Bismarck, due to her larger hull.
Bismarck will have completed speed trials and though the figures may be disputed the ship is logged has having made 30 knots for a short period during the passage through the Denmark Strait.
Vic
Re: BS speed - last battle
The original design of the KGV called for 100,000shp, but this was changed during building and the actual full power continuous rating of the PP was 110,000shp. Allied BBs gives the SHPs produced by PoW during the run to intercept Bismarck and these are confirmed by PoW's log entries, showing commensurate speed increases. PoW made 28.0 knots with 111,600shp at 42,100 tons on trials,and her log records 28.8 knots from 0400 to 0500 and 29.1 knots average from 0500 to 0600, May 24. These log speeds are corroborated with rpm figures, that indicate SHPs well above 110,000SHP. PoW probably averaged about 125K SHP from 0400 to 0600, with power peaking towards 0600.Vic Dale wrote:In all naval machinery and equipment, there was a normal working load and an emergency over load condition.
The Admiralty turbines fitted in the KGV class had a normal maximum output of 100.000 shp, giving a maximum speed of 28.5 knots at standard displacement and 27.5 knots at full load. In emergencies this could be extended to 110,000 shp, giving 29.5 knots at standard displacement and 28.5 at full load.
In a dire emergency, this could be extended even further for a short time and I believe the captain would signal this to his engineers by putting the telegraph to full-ahead three times.
Of course added shp and shaft revolutions do not make for a specific increase in speed, since hull=form imposes it's own limits on a vessel's speed and every class of ship is different. A foul bottom can drastically reduce speed also.
Sea temperature also plays it's part in governing ship's speed. Cold water will make the condensers work more efficiently causing a greater differential between the pressure and the vacuum ends of the turbine, making it behave as if greater steam pressure had been applied. Warm water will reduce this efficiency and in turn reduce speed.
The KGVs were much smaller ships than the Bismarck class and had an immersion of 1 foot for 1300 tons as compared to Bismarck's of 1 foot for 1600 tons. This means that the difference between the standard and the full load displacment condition would cause a 25% greater draught increase in the KGVs than in the Bismarck class and a proportionately greater loss of speed.
Bismarck's hull form produced a greater waterline length than the KGVs and will have permitted a higher speed, so the reduction in speed at full load will be less in Bismarck also. So where a 1 knot differential in speed is calculated for the KGVs between full and standard displacement, only about half a knot reduction will apply to Bismarck, due to her larger hull.
Bismarck will have completed speed trials and though the figures may be disputed the ship is logged has having made 30 knots for a short period during the passage through the Denmark Strait.
Vic
Bismarck's reconstructed war diary shows that an increase of speed from 28 to 30 knots was ordered, but rescinded about two minutes later.
Remember that Bismarck has a very low Length/Beam ratio due to her exceptional beam, but I am not comparing KGV to Bismark, but instead compared Vanguard, Richelieu and VV, but a comparison to S&G is also interesting, and I'll give info on that shortly.
Re: BS speed - last battle
Hi again Dumunro
The beam to length ratio in Bismarck was only 5% greater than that in PoW, so I think we can reasonably disregard that as a factor, since Bismarck's waterline length was much greater than PoW's making for a higher designated speed. She would make 29-30 knots with less of a percentage increase in shp.
Dulin and Garzke have the KGV class equipped with boilers and engines with steam conditions set for 400 psi at 700 deg. F. to produce 100,000 shp and with a short-term overload of 110,000 shp.
There will have been slight variations in various speed trials, since it is very difficult to set the exact conditions for each run, due to fuel consumption and feed water and other factors impinging on displacement. Changes in sea temperature will make the condensers work more or less efficiently and this will cause variation in shp attainment.
The speeds recorded in PoW's log (can you give me a useful URL to this document?) will have been recorded by Pitometer log and as I said earlier, the very cold waters in the Denmark Strait will have given an increase in speed through faster shaft revolutions, though with steam pressure still within the absolute maximum, due to the condensers working more efficiently than they would on the Arran mile.
Vic
The beam to length ratio in Bismarck was only 5% greater than that in PoW, so I think we can reasonably disregard that as a factor, since Bismarck's waterline length was much greater than PoW's making for a higher designated speed. She would make 29-30 knots with less of a percentage increase in shp.
Dulin and Garzke have the KGV class equipped with boilers and engines with steam conditions set for 400 psi at 700 deg. F. to produce 100,000 shp and with a short-term overload of 110,000 shp.
There will have been slight variations in various speed trials, since it is very difficult to set the exact conditions for each run, due to fuel consumption and feed water and other factors impinging on displacement. Changes in sea temperature will make the condensers work more or less efficiently and this will cause variation in shp attainment.
The speeds recorded in PoW's log (can you give me a useful URL to this document?) will have been recorded by Pitometer log and as I said earlier, the very cold waters in the Denmark Strait will have given an increase in speed through faster shaft revolutions, though with steam pressure still within the absolute maximum, due to the condensers working more efficiently than they would on the Arran mile.
Vic
Re: BS speed - last battle
Ship.....WLL.....beam..draft..WLL/B..speed..shp....displacement
Bismarck....792...118....??.....6.69...28.374.117410...75% load (?)
PoW.........740...103....32.5...7.18...28.....111600...42100
Victorious..710...95.9...29.3...7.45..30.5....111000..~28000
Vanguard....799...108....32.....7.4....31.57..135650..45720
Vanguard....799...108....35.....7.4....30.38..132951..51,070
Richelieu...794...108.5..30.5...7.32...30.31..132798..42056
VV..........770...108....31.7...7.13...31.43..132775..41473
Scharnhorst.754...98.4...??.....7.66...29.9...125756..~36000
From reading Koop it would appear that Bismarck's PP was essentially a
repeat of Scharnhorst's but with lower rated boilers. Yet somehow, magically
Bismarck is able to achieve almost identical speeds but with a de-rated PP!
This doesn't seem likely to me. In fact at full power, in deep load, Scharnhorst
was hard pressed to exceed 30 knots, yet Bismarck with less
power and 12000 more tons displacement, at deep load, is claimed to do 30 knots!
This is highly unlikely.
75% load could mean 75% of her load, calculated as light ship versus full load,
or 38000-48000 = 10000 x .75 = 38000 + 7500 or ~45500 tons. However, it could
also mean max full load x .75 = ~38000 tons and the above speeds are about what
one would expect at that displacement and power figure, given Bismarck's hull form.
VV's trials data seem quite suspect as well, compared to Richelieu and Scharnhorst.
Vanguard's transom stern gives her a big edge in efficiency.
Finally, compare Victorious and PoW , with Bismarck and Scharnhorst. On 14000 tons less displacement Victorious gains 2.5 knots with the same SHP. Yet Bismarck, displaces 13000 tons more than Scharnhorst, but is less than 1.5 knots slower but has 8 to 10000 less SHP?
Bismarck....792...118....??.....6.69...28.374.117410...75% load (?)
PoW.........740...103....32.5...7.18...28.....111600...42100
Victorious..710...95.9...29.3...7.45..30.5....111000..~28000
Vanguard....799...108....32.....7.4....31.57..135650..45720
Vanguard....799...108....35.....7.4....30.38..132951..51,070
Richelieu...794...108.5..30.5...7.32...30.31..132798..42056
VV..........770...108....31.7...7.13...31.43..132775..41473
Scharnhorst.754...98.4...??.....7.66...29.9...125756..~36000
From reading Koop it would appear that Bismarck's PP was essentially a
repeat of Scharnhorst's but with lower rated boilers. Yet somehow, magically
Bismarck is able to achieve almost identical speeds but with a de-rated PP!
This doesn't seem likely to me. In fact at full power, in deep load, Scharnhorst
was hard pressed to exceed 30 knots, yet Bismarck with less
power and 12000 more tons displacement, at deep load, is claimed to do 30 knots!
This is highly unlikely.
75% load could mean 75% of her load, calculated as light ship versus full load,
or 38000-48000 = 10000 x .75 = 38000 + 7500 or ~45500 tons. However, it could
also mean max full load x .75 = ~38000 tons and the above speeds are about what
one would expect at that displacement and power figure, given Bismarck's hull form.
VV's trials data seem quite suspect as well, compared to Richelieu and Scharnhorst.
Vanguard's transom stern gives her a big edge in efficiency.
Finally, compare Victorious and PoW , with Bismarck and Scharnhorst. On 14000 tons less displacement Victorious gains 2.5 knots with the same SHP. Yet Bismarck, displaces 13000 tons more than Scharnhorst, but is less than 1.5 knots slower but has 8 to 10000 less SHP?
Re: BS speed - last battle
Hi Dunmuro.
Scharnhorst carried a very large bulbous bow below water, which may have caused a good bit of drag. Bismarck didn't have a large bulb on the forefoot.
Near the top end of the speed range, a battleship takes a lot of driving and perhaps this bulbous bow added a disproportionate hamper to Scharnhorst's speed, thus negating the increase in speed which her more powerful engines should have supplied.
It appears that some speeds are given but at less shp than the ship was capable of generating.
Speed, shp and endurance figures are very mixed between these types of book and it often takes considerable research to get anywhere.
Vic
Scharnhorst carried a very large bulbous bow below water, which may have caused a good bit of drag. Bismarck didn't have a large bulb on the forefoot.
Near the top end of the speed range, a battleship takes a lot of driving and perhaps this bulbous bow added a disproportionate hamper to Scharnhorst's speed, thus negating the increase in speed which her more powerful engines should have supplied.
It appears that some speeds are given but at less shp than the ship was capable of generating.
Speed, shp and endurance figures are very mixed between these types of book and it often takes considerable research to get anywhere.
Vic
Re: BS speed - last battle
Why does one put a large, bulbous bow on a ship? I thought it was to improve hydrodynamic efficiency. That should help, not hurt maximum speed.
These numbers just don't always make sense. Iowa and New Jersey were capable of only 31.5 kts during the Truk run, on 212,000 shp. Yet dunmunro gives Vanguard the same speed on much less power. Odd.
These numbers just don't always make sense. Iowa and New Jersey were capable of only 31.5 kts during the Truk run, on 212,000 shp. Yet dunmunro gives Vanguard the same speed on much less power. Odd.
Re: BS speed - last battle
Typically a bulbuous bow was added to a ship to increase its underwater efficiency at high speeds. Bismarck also had a similar bow design. The easiest way to explain the disparity in power and speed of Bismarck and Scharnhorst, is that Bismarck was not as fast as often claimed.Vic Dale wrote:Hi Dunmuro.
Scharnhorst carried a very large bulbous bow below water, which may have caused a good bit of drag. Bismarck didn't have a large bulb on the forefoot.
Near the top end of the speed range, a battleship takes a lot of driving and perhaps this bulbous bow added a disproportionate hamper to Scharnhorst's speed, thus negating the increase in speed which her more powerful engines should have supplied.
It appears that some speeds are given but at less shp than the ship was capable of generating.
Speed, shp and endurance figures are very mixed between these types of book and it often takes considerable research to get anywhere.
Vic
I have examined numerous sources for this info, and the data for Bismarck just doesn't add up to the speeds claimed. I think the claim for 30.1 knots can only be true at an unrealistically low displacement, with the theoretically achievable power, but it is highly unlikely this was achieved in service, hence the need for Lutjens to try and reduce displacement somewhat so that Bismarck would have a realistic chance to outrun a BB pursuer.