Modern vessel performance compared with WW1 types.

Discussion in 'The Fleet' started by EX_STAB, Jul 13, 2008.

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  1. I came across this video on Youtube showing HMS York on sea trials. (Apparently)

    Clipping along very nicely at 30 kts with a fuel consumption of 44 gallons per minute according to the video.

    Now it seems to me that this isn't a huge improvement on vessels of the first world war ninety years ago. In fact if 30 kts is top speed then it's something of a retrograde step.

    A quick scan through the more common types of WW1 and WW2 reveals that 36 kts was the standard design speed for destroyers. This was with heavy-oil fired boiler and steam turbines. A quick look on everyone's favourite unverified source reveals that A WW1 V class Flotilla Leader (an exception to the rule, only made 34 knots) with a bunker capacity of circa 350 tons had a range of 900nm. With heavy fuel oil at 0.93kg/l I make that 49 gallons a minute.

    Extrapolating a little further we could calculate a gallons per minute per knot rate for these vessels.
    we get:
    HMS York 1.47 GPM per knot
    WW1 V class 1.53 GPM per knot.

    Out of interest, for the WW1 V Class at 15 kts the fuel consumption rate works out at 2.85 Gallons per minute.

    Clearly a first world war destroyer was a lot smaller than a modern one but it was still a potent vessel.

    If we look at something bigger like the 3,500 ton HMS Arethusa Light Cruiser, built in 1913, at 29 knots it used 550 tons of oil per 24 hours. That works out at 43.5 gallons per minute, at 24 kts it used 260ton/24 or 13.5 gallons per minute.

    The 1913 Arethusa was about 1300 tons less than HMS York (Around 2/3 the displacement) but even so I think the comparison is worth making. It had:
    3 × 6 inch guns
    4 × 4 inch guns
    2 × 3 inch guns
    8 × 21-inch (533 mm) torpedo tubes
    Which compares well with two missile launchers and one gun on a 42. (Yes, helicopters, I know but it certainly had teeth - and armour!)

    No doubt the experts can come up with some better data than I can but it is a topic that raises a lot of questions to my mind.

    My Grandfather's ship in WW2 (HMS Wallace built 1917) made 38kts on trials.

    The modern navy seems slower and just as thirsty.

    Here are some sources for hte above data:
  2. Dont forget that the fire power of a modern warship is considerably more than a WW1 warship,that is assuming that they are actually carrying weapons of course!
  3. Ex_stab,

    It's the same reason that airliners haven't got faster in fifty years, and road vehicles still work around the same sorts of speeds too: barring some magical improvement in engine efficiency, or a rewriting of the laws of hydrodynamics, it takes about the same amount of fuel to push a similar-sized hull through the water at the same speed.

    Top speeds have dropped off a little because (a) you got diminishing returns from adding power, which is why 36 knots or so ended up the upper bound even for really fast destroyers; (b) the utility of those last few knots is a lot smaller these days now destroyers aren't trying to head off enemy S-boats or charge in with their own torpedoes. When sailors were chasing shell splashes or combing torpedo tracks, speed was significant, and a knot or two's advantage meant choosing the range in a gun duel: whereas now, nobody's going to outrun an ASCM.

    You can save a remarkable amount of machinery and the fuel to power it, if you accept a top speed of 28 knots rather than 32 - the power/speed curve gets really nasty for smaller ships there.

    Another note is that top speeds can be one of those polite fictions where remarkable figures get quoted: either done under unique circumstances (ship stripped out light, really cold water, and exactly the right depth under the keel) or simply exaggerated for publicity. A couple of "famously fast" ships actually got a bit broken on speed trials - the battlecruiser HMS Princess Royal was officially credited with 34.7 knots, but when she ran the Polperro Mile in 1913 she actually only managed 28 knots, and that was with the safety valves wired down and the machinery forced past its limits; she was a lame duck with constant engine trouble for the rest of her career.
  4. Seaweed

    Seaweed War Hero Book Reviewer

    Spot on Lynch. However an escort to a carrier will need to keep up and a carrier needs speed to put wind over the deck in calm tropical conditions. One of the problems with Frog CdeG was her being too slow; same problem with our Light Fleet carriers (Colossus class) once out of our lovely windy North Atlantic. Does a steam catapult make this no longer a problem? Wafus please advise.
  5. It's more effective due to radar and guidance but does it actually carry a higher weight of warheads?

    HMS Arethusa again:

    4x 4" guns 200 rds each. 14kg projectile per round = 11200kg Source
    3 x 6" guns 150 rds each, 45 kg projectile per round = 20250kg source

    21" torpedo assuming 21" MkIV 235kg each. Four tubes so let's say three per tube ( I think this is probably a very modest assumption), 12 torpedoes = 2820kg

    I've disregarded the 3" guns which we might in modern terms balance off against the Air defence requirement so total offensive warhead payload against vessels:
    Total offensive warhead payload for shore bombardment:

    How does this compare with the modern payload carried?

    Arethusa class carried a floatplane too so it even had an air element even though it would be rather weather dependent and only of use fo rspotting. I'm not suggesting that we start building ninety year old designs but perhaps there are lessons here?

    The Arethusa class for example was noted for being cramped. I gather that on type 45s everyone has his own cabin. Are we compromising efficiency for luxury? (Rhetorical!)
  6. On raw poundage, really badly.


    Hit probability of guns at that point was about 2%, torpedoes between 2% and 10% (depending what data you use).

    So, of the shells, you could expect about 630kg of shells to actually *hit*. However, those shells were only about 10% explosive, and it's the HE that does the hurting (as a very rough rule of thumb, but OK for a light cruiser). The gun armament puts a spuriously precise 63kg of HE on target.

    Torpedoes, you've got four tubes (two each side) and realistically no chance of a hit unless you're finishing a cripple. But, okay, allow one hit for a 235kg payload. No reloads - reload torpedoes tended to be rare, they're big and heavy and vulnerable (one theory for HMS Hood's loss is her torpedo flat going up). Battleships and some Japanese cruisers had reload torpedoes, most had loaded tubes and that was it.

    Compare to something more modern like a T22B3[1]. One Mark 8 gun with a handwaved 300 rounds in the magazine. Loses out to the Arethusa - you should get more hits at short range, but that means the fight tends to happen further out.

    Eight Harpoon missiles. Be generous to the target and say only half hit, that's about 200kg of HE per missile, so 800kg on target.

    Goalkeeper. No HE at all, but turns aircraft and missiles into aluminium confetti with reasonable efficiency. Doesn't translate to a 1913 design.

    Sea Wolf. Again, doesn't really fit 1913: they didn't have many aircraft worries and certainly didn't care about ASCMs.

    Sting Ray, either from helo or STWS. Pretty good against modern submarines: death by the bucketful to WW1 submarines who won't know what it is until it kills them. Hard to classify.

    Sea Skua, for the Lynx - 28kg of HE per shot, usually hits so far, don't know how many are standard load aboard. Works at night and in bad weather, too, so a 1913-built target is limited to damage control and wondering where those big bangs are coming from.

    So less total tonnage of metal to throw. But, much more HE likely to arrive to lethally upset the target, and much more ability to hit and hurt at long range, and the capability remains lethal at night and in bad weather when the Arethusa's down to searchlights and binoculars (there are some harrowing accounts from the night action during Jutland of ships closing on dark shapes and flashing recognition signals, only to get devastating storms of shellfire in return when they offered a UK challenge to the High Seas Fleet)

    The one area that the older ships have a big edge at, is counter-FIAC: if you're fighting small gun- and torpedo-boats, having lots and lots of quick-firing guns available is a real advantage.

    Otherwise, put HMS Arethusa up against HMS Campbeltown, and Arethusa's first warning that she's in trouble is a salvo of Harpoon blowing her apart. Take those out as unfair, and she gets crippled by Lynx using Skua. Disallow those, and she's getting taken apart by 4.5" shellfire from ranges that seem ludicrous to 1913 fire control systems and - if the weather's bad or it's night-time - she doesn't even know who's shooting at her. Unless the T22 does something stupid, she can shoot her magazines empty and then disengage at will.

    There's a visceral appeal to lots of simple guns as an antidote to technology, but that was the Iraqi option in 1991 and 2003 and look how well it worked for them...

    Yes, I'm a sad spotter. So sue me. I already get to do my hobby for a living javascript:emoticon('post',%20'message',%20':rambo:')

    [1] For modern stuff, numbers are Janes and Harpoon and Wiki and other open source, so may not agree with them as know.
  7. The problem as I have read with the post WW11 ships is the extra electical power thats needs to be generated to run the vast amount of Combat Control equipment and the weight of the generators and the equipment to distrabute the same. Add the extra top weight of Masts and ariels and any comparison even between a WW11 Tribal and a Leander are really meaningless.

    N Utty
  8. Agreed with the technicalities of pretty much everything you state but I think you're missing my point slightly.

    Take HMS Arethusa. Fit modern fire control systems to the guns, replace the torpedoes with Harpoon, replace the 3" and under guns with the modern air defence option. OK, at this stage we haven't got a helicopter but I would bet there is room for one and displacement if you did away with the armour. (3" armour being useless nowadays)

    You've got a 90 year old hull with more offensive capability than a modern vessel at the same speed and fuel consumption.

    Why doesn't a modern design carry this payload at higher speeds or at least at better fuel consumption?

    The crew would have to sleep in hammocks though ;)
  9. It's also issues like armour: if the threat is 4" shellfire then slabs of armour down the side of the ship make sense. If the threat is a ton of missile arriving at Mach 0.9 with a SAP warhead, armour just annoys it. (Even early Exocet was claimed to be able to beat 11" of rolled plate, which sounds optimistic but not utterly unbelievable - certainly I would expect it to get through light cruiser protection)

    Then you have problems with topweight: gun mounts need large magazines with lots of shells, charges and handling equipment down low, while modern ships want big heavy sensors as high up as possible, and don't do deep magazines, so while classical ships used to be tonnage-limited, modern vessels are constrained by stability.

    I'd highly recommend David Brown's books on RN ship design to anyone interested: the cartoon on page 83 of my copy of "Nelson to Vanguard" makes Nutty's point perfectly, where a perfectly good light cruiser has lost most of her useful weapons as weight compensation for the "other stuff" found to be essential.
  10. So has the punch per ton lost out to stuff that doesn't sink, burn or destroy the enemy?
  11. Hi Lynch,

    I've come back and reread this. So law of diminsihing returns applies regarding fuel performance. Understood. Staggering that 90 years of engineering development hasn't improved fuel consumption at all though. I bet the maintenence regime for a gas turbine engine and associated eqpt is far greater than that for an oil fired boiler and steam power plant though. Is this progress?

    If we accept a top speed 0f 75% of what our great grandfathers could achieve, shouldn't we have a hell of a lot more offensive capability than we do? Has it all been taken up with comfy bunks? ;)
  12. In a Nutty Shell Yes.

    I am ploughing thru British Destroyers and Frigates WW11 and After" Starts with the Tribals and goes thru destoyer and frigate design and development to Type 42 and hints onto Type 45. You would be amazed at how long most of thes post WW2 types were in gestation before they came into service.

  13. EX_STAB,

    Adding "modern fire control" to the guns means serious sensors (lots of topweight), and lots of extra electricity consumption compared to a 1913 ship (where electric lights in the messdecks were a cause for concern - what if Jack Tar used it to read Bolshevik propaganda?) and lots of extra weight on each gun mount (because instead of firing in local control, you need stabilised mounts in director control). Even lashup conversions towards that end in WW2 usually lost a quarter to a third of the main guns to make space and weight for the kit required.

    Losing the armour means the hull buckles - no cheap solution there. (It's almost worth keeping a belt below the waterline for stability purposes, but most ships with armour used it for structural strength - lose the armour and you have to rebuild and strengthen the hull in a big way)

    As to asking crews to accept even WW2 levels of life... I'd strongly recommend a visit to the USS KIDD in Baton Rouge, Louisiana. Very well cared-for museum ship, excellent example of a late-WW2 destroyer, proud battle history. Take a look at her messdecks and recall that the USN were mocked for the luxury of their ships.

    You will not get volunteers to do second tours on that ship in peacetime cruising. If you can't get the crew, your ship is as useless as any other piece of unmanned equipment.

    Current constructors and designs are far from perfect, but they aren't idiots and they aren't missing easy options. If there was a way to make a warship faster, cheaper, better, it would at least be proposed. (Most of the really bone decisions seem to come back to politics, more's the pity - which since I'm CS makes it 'my fault', but I'm not allowed to hunt down and kill the idiots responsible for the worst calls so I can only slope my shoulders)

    Modern ships carry much more *deliverable* payload, at lower speeds but more economically (and RAS lets them do it for far longer) and the crew gain experience and then some of them stick around to pass on their knowledge. That's not to defend the fit of current hulls to tasking, or details of design, but you will not gain capability by making a reworked 1913 Arethusa into the Future Surface Combatant.

    There are some awful howlers made by naval architects, but in general they do their best: if it was possible to get a better warship by dusting off old blueprints, we'd be hearing about it.

    Why doesn't a modern ship carry the same payload? Because it carries a smaller payload that's far more lethal. If you add up the weight of lead that one of Wellington's musketeers carried, it's rather more than the weight of bullets carried by a modern infantryman... but would a 1800s soldier win that fight?

    Why doesn't it burn less fuel, or go faster? Because Froude's equations still hold. It takes X amount of power to push 5,000 tons of well-designed ship through the water, and X horsepower require you to burn Y tons of fuel per hour, and the improvements in those numbers has been strictly incremental in the last few decades. After the steam turbine and the small-tube boiler, the big wins were taken.
  14. I just find it astonishing that the best efforts today don't produce better results than the best efforts of ninety years ago. The hull calculations I can understand are a physical limitation but no improvement in powerplant efficiency for ninety years? That is astonishingly poor!
  15. The Screw prop. Brunel designed for the SS Great Britain is only slightly less efficient than the modern prop. fitted to most ships today. Perhaps the engineers of 90 odd years ago had just about got it has right has it would ever be!
  16. It's not just about fuel consumption at max chat, it's about availability. Steam turbines needed _hours_ to get to max speed from a cold start, needing every boiler lit and brought to working temperature: gas turbines can go from shut down pierside to full speed in fifteen minutes. That flexibility is nice.

    The efficiency of various sorts of engines hasn't changed that much in decades. We've done the easy part, now we're stuck with thermodynamics until someone comes up with a miracle.

    We could maybe get a modern destroyer past 40 knots for a measured-mile sprint... but it would have a gun forward, a helicopter aft, and not much else, and she would suck her tanks dry in a few hours. What does that extra ten knots of top speed gain you? Conpared to useful weapons and sensors on less extreme ships?

    And gas turbines need a lot less looking after than steam plant. While we probably could produce steam turbines as automated as modern machinery, historically it needed a lot more cosseting than modern kit (if nothing else, an Arethusa needed stokers shovelling coal instead of pumps delivering dieso)

    It's late, I'm "tired and emotional", and I'm not addressing your concerns properly, but you deserve more than "I'm right and you're wrong!" even if that's how this post reads. Keep hitting me for issues you disagree with.
  17. In which case the question has to be:

    Is the modern powerplant cheaper to install, operate and maintain than the powerplant of ninety years ago? Frankly, it bloody well ought to be!
  18. The easy stuff has been done a century ago. Now we're working on details.

    Thermodynamics tells us what sort of efficiency we can expect for burning X amount of fuel (heating our working fluid to Y working temperature, rejecting waste heat to a sink at Z degrees - look up Carnot, nobody's proved him wrong yet) and we're a little closer to that limit now than we were in 1908 - but there's not that much improvement to be had unless our physics is radically wrong.

    Barring magic or a radical rewrite of the Rules of the World, the main improvements available are things like shorter notice to move or fewer stokers needed below decks.
  19. This is a very interesting thread.

    Without wanting to change the subject at all, it all sounds very like modern medicine.

    The chances of me getting a disease named after me are slim mainly because:

    1. I'm not that intelligent.
    2. I'm not that lucky.
    3. I'm too late.

    With a couple of exceptions, any disease that could be discovered has been discovered. I suspect it is the same for marine engineering - the constants are still there and are still tricky to overcome.

    The comparison with almost 100 years ago is interesting, and further forwards Brunel as one of the geniuses of his (and possibly all) time.

    As Mr Lynch has said, we're playing with small print now. Having said that, when a big improvement comes it'll be big.

    Question for the MEs out there: would nuclear power to surface vessels make things any easier? (Other than pissing off Portsmouth City Council)
  20. I think we are forgetting the abilities of the older ships to stand a lot of punishment before being totally disabled and possibly sinking.

    Have seen photo's of various ww2 vessels being used as targets for modern weapon trials and of course fleet target practice. Scarred and battered but still floating . Most ship systems and weapon WW2 had
    ''hand control '' modes for machinery and weapons .

    New construction seems to be automated to the last nut and bolt --lots of crew comforts and as we saw during the Falklands with Sheffield very inflammable .

    When General Belgrano[ww2 cruiser] was at sea the UK task force was
    considered vulnerable big ship with lots of 6" guns and latterly fitted with
    missiles too. Could have been a very bad news day if she hadn't been torpedoed.[with a ww2 vintage weapon]

    As mentioned war now is possibly a different scenario -- no ship contact
    just guided missiles fired on radar bearings .However unless the missile
    does irrepairable damage then the 'target ' will retaliate .

    Would be an interesting combat item WW2 armoured gunship v new
    construction warship in a surface action.

    :nemo: :nemo:

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