HMSWarspite
Posts: 1401
Joined: 4/13/2002 From: Bristol, UK Status: offline
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Interesting little detour through the US CV actions, but what about the original issue? How much damage to PH dock facilities can a first strike cause, and how long do they take to repair? Mogami? BTW as an engineer myself (although not either Civil, or Naval) I do think that certain ascertions about the speed of repair of dock facilities are being overstated. As part of my study of the GG strategic bombing games (Battle of Britain, and Bombing the Reich), I have come to some general conclusions about bomb damage modelling. Bomb damage on shore installations (e.g. factories, port installations, airfields etc) should be divided into 2 parts: I call them 'light' and 'heavy' (not to be confused with a level of damage - note to self, think of something better to call them). Light type damage is all those elements that can be caused by almost any bomb (100lb, incendiary, 500lb GP, whatever). It represents blowing roofs off, knocking down domestic house type walls, electricity supplies, small craters in roads, fires etc. It is reasonably easy to cause, and reasonably easy to patch up, given supplies of material, labour etc. (Here I agree with mdiehl) Heavy type damage comes in two flavours. Type 1 is things like machine tools, which are inherently hard to destroy (being basically a lump of cast iron in this period) and needing big bombs to do it. For example 1000lb GP and up, 4000lb HC (RAF weapon) etc. Type 1 also includes unique facilities that are 'small', but vital, say floating docks. Type 2 is anything that is well protected (say a hardened shelter like a U Boat pen). The level of protection defines the smallest bomb that will damage it. Any target can now be thought of as a 'light' constituant, and a 'heavy' constituant, with a rating for the 'heavy' that sets the smallest bomb that will damage it. The output of the facility could be throught of as 'light effectiveness times heavy effectiveness'. The key thing about damage is that light damage (as said earlier) is quick to repair. Heavy damage is slow to impossible to repair. Some examples may help. Lets take an airfield, a ball bearing (or heavy engineering) plant and, oh lets say a dock yard :). An airfield is almost exclusively 'light'. So any damage to an airfield will be quick to repair, but the airfield is relatively easy to damage. A small part (the engineering hanger, the fuel store etc) is much harder to repair, but the field can improvise and operate anyway to an extent. Only if (by great luck, or a really heavy raid by level bombers) the heavy bit gets hit (say >2% chance) does the airfield performance really get hurt for long. A ball bearing plant might be 50% light, 50% heavy (say), and the heavy will be 1000lb bombs and up. This means a really successful B17 raid with 500lb bombs could completely 'destroy' the plant (reduce the light to 100% damage, and hence output to zero). But the damage would repair quite quickly. A raid with bigger bombs would be required to take it out for good. (Any resemblance to Schwinefurt is purely deliberate!) Now, lets take our dock yard. Or lets take 2 in fact, St Nazaire conventional dock yard, and the U boat pens. U boats pens first, target characteristics say 20% light, 80% heavy (type 2!) with 12000lb Tallboys to damage. You can see that conventional raids will be a nuisance, and could slow things down for a few days, but most bombs are going to hit the pens, and do nothing. The 20% light may be a bit generous, but represent all the auxilliary buildings. IIRC, the Germans got round this by just moving them in to the pens, so you probably get 20/80 as built, but upgraded to 1:99 or something (i.e. immune to anything other than specials!) St Nazaire conventional docks is still a special case because it had a unique feature: the Normandie dry dock. This was actually destroyed by a Commando raid, but this one raid knocked out the whole port for weeks, and the dry dock for the rest of the war. (In answer to someone who asked where to aim on a dry dock, the answer is the dock gate, with the pumping gear and generators as a second choice). This gives St N as maybe a 95% light target ( it doesn't matter too much, because it is a unique case). Most damage can be repaired quickly, but if someone gets lucky and hits the dock gate, or a pump, etc, it could be out for a long time. This principle can be used for most targets. It enables the different characteristics of differenr targets to be modelled, and gives a sort of 'critical hit' result for each target type, as well as rewarding heavy bombers against CV air power. Now, back to PH. I do not know enough about the facilities, but I would suggest that there IS a level of facility that cannot just be repaired by bulldozing the crater and 'relaying the track'. It may be the fuel tanks, or more likely the pumping station. It might be the power supplies, or the dry dock gates, or the floating dock, or whatever. However, you should find it difficult to knock PH out for long, but equally there MUST be a chance that you can do something really vital. Say PH is a 90:10 target, and taking Mogami's 86% damage from before. Split equally, the damage would give 14% output, the evening of the raid. More realistically you would give more damage to the light, and say give only 10% to the heavy. This would give full 'light' recovery in say 1-2 weeks, but in that time the heavy wont have moved, so total port output would be still 90% of the maximum. The remaining 10% would come back much more slowly. In UV terms maybe a step every time 10000 supply points dock or something. However, if the IJN get very lucky, and (v rarely) do 50 or 80% damage to the heavy facilities....PH only at 50%, or 20% effectiveness for months anyone...? A single (linear) damage level cannot model the real factors in damage repair well enough IMHO This is a bit of a ramble, but it represents a way of balancing mdiehl and his 'replace in a week' vs others feeling that you can hurt PH to strategic effect.
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I have a cunning plan, My Lord
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