DougToss

@Nick Thomadis You'll probably understand what this means mechanically better than I do, but I pulled the relevant passages: Stability and Capsize For much of the second half of the nineteenth century, the design of warships was dominated by problems of stability, which must be explained if the reader is to follow the great and angry debates of the time. The principles of ship stability are simple but the calculations needed to quantify the values for a real ship are so long and difficult that complicated mathematical methods were soon introduced to reduce the amount of arithmetic involved. Though these methods eased the work of calculation, they also obscured the basic simplicity of the subject. The subject of stability advanced very rapidly during the 1860s, due to Reed and his brilliant assistants, though many, including some well-qualified naval architects, failed to understand the implications of this new work. Even the word ‘Stability’ is used with at least three meanings which differ one from the other. Stability is used to describe the force needed to heel a ship through a small angle; the ship being described as stable if a fairly large force is needed to heel it. A ship is also said to be stable if it can be heeled to a large angle without capsizing and, although this is a proper meaning of the word, it is not the same as the first case. A ship can require a large force to heel to a small angle and yet capsize at an angle little greater. Finally, the word stability is often used to describe a ship which does not roll violently. As shown in Appendix 5, this usage is incorrect as it is almost the opposite of the first two meanings of stability. Forces in Balance When a ship is floating stationary in still water, there are just two forces acting on it, weight and buoyancy. The weight is constant – equal to the displacement – and will act vertically downwards through the centre of gravity which, with some exceptions discussed later, is a fixed point. Buoyancy must equal weight for a floating object by Archimedes’ principle and will act vertically upwards through the centre of buoyancy which is not fixed. The centre of buoyancy is the centre of the underwater volume of the ship and, since this volume changes shape radically as the ship heels, the centre will move. With the ship upright these two forces will be equal and opposite and work in the same line, balancing completely (the first, uppermost small sketch). As the ship heels, the underwater volume will increase on the immersed side and reduce on the emerged side so that the centre of buoyancy moves to the immersed side (the next three small sketches). One may envisage a ‘wedge’ of volume being transferred from the emerged to the immersed side. The forces of weight and buoyancy, though still equal, no longer act in the same line but are separated by the distance GZ. This length is referred to as the righting lever and the product Weight or Displacement (W) times GZ is the righting moment. For small angles of heel the buoyancy force is outboard of the weight and the righting moment will try to bring the ship upright. For normal ships the righting moment and lever (GZ) will increase quite rapidly at first as the ship heels more and more but as the bilge comes out on one side and the deck edge goes under on the other, the GZ will increase more slowly and finally begin to reduce. The angle at which the maximum GZ occurs is critical; if there is a steady force heeling the ship and the heel passes the maximum, the righting moment will decrease and capsize will follow very quickly. Eventually, the righting moment falls to zero (the angle of vanishing stability, 82° in the fourth and lower sketch) and will become negative, the buoyancy force increasing the heel (the fifth small sketch).” The Curve of Righting Levers (GZ Curve) The features described in the previous section can be shown on a graph where the value of the righting lever is shown on the vertical axis for each angle of heel (the curve below the sketches). As well as the angle and value of maximum GZ and the angle of vanishing stability (the angle at which it occurs is sometimes called the ‘range of stability’), the so-called down-flooding angle is important. This is the heel at which water will begin to pour down gun ports, hatches, funnels, ventilators etc, and is the practical limit beyond which survival is unlikely. In the early years undue importance was attached to the range of stability instead of the down-flooding angle. The key factors are the maximum value of GZ and the angle at which it occurs and tables in the text for individual ships will usually be limited to these figures (when available). The adequacy of a GZ curve can only be judged in relation to the heeling moment to which the ship may be exposed. The heeling moment will include some or all of the following; the effect of wind pressure on superstructure, masts and rigging, wave forces, shifting cargo or other loads, crowding of people to one side and flooding. An all too common build-up to disaster sees a ship broadside on to wind and sea. The ship heels over to leeward to a considerable angle due to wind pressure and on this is superimposed large roll angles due to the waves. There will then be slow flooding through intakes, leaking hatches and doors etc. Such flooding can lead to loss of electric power (in modern ships) and hence to steering; followed by more flooding and capsize. Between 1935 and 1945 the USN lost four destroyers in much this way, the Italian lost two, Japan one, Russia one – and the RN none. The resistance to short-duration forces, such as a gust of wind, is measured by the area under the curve so the naval architect will refer to a GZ curve as ‘good’ if it rises quickly at first, reaches a satisfactory maximum at a fair angle and has plenty of area beneath it. These subjective values have now been quantified. Approximations and justification It was realised from its introduction that the GZ curve was only an approximation to the behaviour of a ship in a severe storm. The GZ curve implies the ship at rest in a flat sea, very different from moving through giant waves. The justification is that it works, at least in a comparative sense. In the century or so after the introduction of the GZ curve it was clear that ships with a ‘good’ curve, as described above, would survive a storm which would cause less well-endowed ships to founder. The loss of three USN destroyers in the great typhoon of December 1944 showed first that the GZ curve was correct in identifying the ships most at risk and also led to an investigation which suggested a way of arriving at numerical values for the good GZ curve. The values derived by Sarchin and Goldberg form the basis for the safety standards of most navies today. Stability at small angles – the metacentric theory It was long believed that the direct calculation of the movement of the centre of buoyancy was so difficult as to be practically impossible and from the seventeenth century onwards an approximation, known as the metacentric theory was developed. This was based on the assumption that the line of action of the force of buoyancy crossed the centre line of the ship (the upright vertical) at a fixed point known as the metacentre (M). The separation of the centre of gravity (G) and the metacentre is called the metacentric height, GM. The righting lever GZ at an angle of heel 0 is then given by the simple expression GM x Sin 0 . This expression is valid up to heels of about 10° for normal ships with a decent freeboard and is useful for estimating heel from shift of weights and moderate winds but is little guide to safety at large angles when capsize is likely. In the early design phase it is often assumed that if the GM of the new ship is the same as that of an existing ship of the same general configuration, then the GZ curves will be similar. Provided that the ships really are similar and the designer is experienced, this assumption is a reasonable starting point. It is not too difficult to calculate the position of the metacentre but the calculation of the position of the centre of gravity (G), though simple, is very lengthy and needs some experience. The height of the metacentre above the centre of buoyancy is given by I/V where I is the second moment of area of the waterplane and V the immersed volume. The height of the metacentre is dominated by the broader part of the hull and hence flooding of the fine ends was not important, often not appreciated by contemporary critics of warship design. The first direct calculation of the position of the centre of gravity (G) was probably by William Bell for the Great Eastern in 1859 but in 1865 Barnaby was to tell the INA that it was so difficult as to be practically impossible. However, more assistant constructors were appointed and very quickly the position of G was calculated for all ships. This position will, of course, vary with loading, G normally being highest in the light condition. The Inclining Experiment The metacentric theory can be used to measure the separation of G and M directly by experiment. A known weight (w) is moved a measured distance (d) across the deck giving a known heeling moment, w x d. The angle of heel (0) produced is measured using long pendulums and then w x d = W x GM x SinØ Since W, w, d and 0 are all known, GM can be found. Damage - Likely the TL;DR All the tedious and difficult calculations discussed above become very much more difficult once the ship is holed and flooded. The ship will sink deeper in the water and will both heel and trim – and even to calculate the position of the new waterline is a lengthy task-whilst the hydrostatic parameters which govern the height of the metacentre and the characteristics of the GZ curve will change. A full treatment of damaged stability was not possible until the introduction of the computer, well after the Second World War. In the early days the effect of flooding a single large compartment was considered by taking the flood water as an added weight, at the virtual centre of gravity. The GM was modified by this and the effect of heel and trim16 considered. It was implicit that the effect of flooding two compartments could be obtained by adding the effects of each compartment taken in isolation. A position for the metacentre in the intact state was obtained, by varying the beam, which, it was hoped, would allow for the losses following serious flooding. There was a reasonable subjective understanding of the effects of damage but the magnitude of the effects of flooding was under estimated, particularly the effect of off centre loading when stability was reduced at the same time. Until at least the Victoria-Camperdown collision the hazards were not appreciated of flooding spreading through doors and ventilation valves which though nominally watertight had either been left open or leaked due to distortion.

@theCarthaginian always happy to see another vet! I was on M777’s. I could write volumes on how 6 in guns perform in game. I also had to hump around a C9 from time to time, and feel your pain lol. This is something I think a lot of veterans and military academics and professionals run into both in wargaming and pop history. Stats on hardware are easily available, and feels like empirical knowledge. It’s so hard to explain the soft factors, doctrine and other differences between theory and practice. This is particularly an issue with AFVs and Warships because I think oftentimes people think it is as simple as placing two tables side by side and comparing statistics. There are a million reasons this is misguided, but as a Canadian my favourite is that as the poor bastards that had to take on the Big Cats in Normandy from day one, including in the hands of 12th SS, the humble Sherman had a favourable exchange ratio, even though you will still hear people say the Allies had to literally send 5 Shermans out to take one Panther or Tiger. It turns out there is more to it than armour thickness and gun calibre! For warships, I think Bismarck and Yamato loom large in the imagination, despite not accomplishing anything towards the outcome of the war, and with the exception of the Channel Dash, not really being that impressive in action. To your point, working in all areas, including Recce, STA and Artillery Command Post, you’re correct on how logs do not always reflect the full picture. I’ll give you an example: Say the counterbattery radar picks something up. That will be processed as one report. Whoever that battery is firing on will also enter a Enemy Shelling Report (shellrep) with location of enemy threat / impact, assessed line to gun line in mils, time between impact and firing. At the same time, anyone who observed flash is sending up their reports, similarly anyone who heard the sounds. We don’t know any of this on the Artillery Net, but our Surveillance and Target Acquisition guys are trying to verify the radar report. Our attached and other EW guys are at work because in 2021 an arty bty is never just the gunline, so they’re looking for the chatter, trying to plot the arty net, observer’s net, looking for their CB radars, doppler and weather radars, other DF stuff. At the same time, our FOOs and OPs are getting run up. Possibly we are operating with battery RPV/Balloon, and are looking with that too. Possibly there is Bde/ISAF/US UAV or other imaging being consulted. We don’t see any of this.l Brigade/Battlegroup has now processed some of the information from the people on other nets and is passing it down to our CP. Our CP is handing up our own reports. There are even more pieces left out here as all of this information is collated at the Staff, run through Bde’s situation map, checked against the Int shop and Bde Arty O, etc. At the end of the day, when all of that is logged in the War Diary, it will read “Battery detected and engaged 1 Arty Bty, at (Grid, mil bearing, range)”, detected by CB Radar, log the time of the initial radar contact! You can see that 1) The Radar Operator was aware of only a teeny tiny part of that,2) the big picture was much longer, more laborious and used other methods, 3) The log alone only shows a sliver and superimposes the later, more complete picture onto the initial contact. Everything that came later explains what it was in hindsight, but it was not apparent, or at least not collated initially.

Brown’s books, and Friedman in Naval Weapons Of World War One talk about the gunhouses and turret layouts of British ships, (Friedman does the other nations as well), and cramped gunhouses and barbettes were a recurring problem for them. Without a space or bulkhead between breaches there were all kinds of accidents and hazards. I think they did have to create quite a large buffer eventually because occasionally flash would enter the gunhouse from one gun and threaten to ignite propellant getting readied for the next. e: I was field artillery, so this was not a problem we had, but the gist of it was occasionally unburnt propellant would vent and ignite into the gunhouse when the breachblock was opened. The 120mm guns on Leopards have fume extractors for a similar reason - even without the flash, you don’t want fumes venting back into the crew compartment.

I like how you snuck that in there! 🥳 Just out of curiosity, because I’m not computer savvy, are there challenges on your end in coding differences between local, central and director control, or is it pretty simple and straight forward? I was wondering if the “nervous system” of a ship in game is the digital version of the “nervous system” period writers described: voice tubes, syncros, telegraphs etc. linking spotters, the Dreyer Table, range clock, gun captains etc. Is each “node” coded, with information passed along, or is it as simple as “telling” the ship “Director Control” and it will know what to do? I hope that makes sense, I’m reading *Naval Firepower: Battleship Guns and Gunnery in the Dreadnought Era* by Norman Friedman, and while it’s daunting visualizing it all to me, I wonder if, as someone who works with code it’s much easier for you to see the bigger picture. I imagine if you have an interest in computing it might be more understandable and more straightforward to translate into game systems, since a warship was a computer. Even if it doesn’t make it in game, I’m dying to hear what you think, because I had never really thought of it in those terms before.

Thank you for helping me find a better way to explain it. You have it exact - after all of the capsize sinkings from torpedos and mines in WW1, later designs were better able to balance flooding, and therefore weight and stability from side to side.

Pre-Dreadnoughts also had a bulkhead here. While in theory it made the ships safer, preventing half the machinery from flooding, in practice it meant that the ship rapidly took on water on one side that could not be pumped out or counterflooded quickly enough, causing capsize.

It’s more that, @theCarthaginian put beautifully, I wonder about theoretical capabilities versus actual utility. Though those reports are in line with the RWR/IRWR comparison I was musing about.

I was going to ask about the dispersion of the first quad turret drawing. Beyond that, I can’t say I know enough about German gunhouses to say how their layout would have to change. Did their breechblocks open vertically or horizontally? The working space needed is probably not as clean as simply multiplying it by 2.

I don’t have Friedman’s book on US Battleships, but regarding the Nevadas’ performance relative the Royal Navy and High Seas Fleet, I’m curious if anyone has tinkered away with The US Ships in Jutland Pro. I think you can even simulate Jutland with the USN standing in for either fleet. Anyone up for giving it a go? I never thought to try the US ships, but I have found it useful to evaluate French warships. I’d be curious to hear how the US ships measure up.

@Nick Thomadis I didn’t mean for that to come across as harsh or blunt. It’s specifically that longitudinal bulkheads were thought to be a good idea initially but caused a tremendous amount of capsizes in that generation of warship. I don’t have my copy handy to pull quotes at the moment, but in Warrior to Dreadnought Brown goes over both the issue of longitudinal bulkheads and machinery spaces, as well as a list of warships built before Dreadnought that hit mines or torpedoes and the result. There have been great strides in flooding and compartmentalization, I don’t want to overlook that, it’s just that without machinery transverse and longitudinal bulkheads aren’t really a problem, if you know what I mean.

I agree that the problem is still that damage, flooding and stability are not modelled well. It’s about time we got rid of Hitpoints. Please, for the love of God! The vulnerability of older Armoured Cruisers and Pre Dreadnoughts to torpedos was in large part due to poor compartmentalization schemes that lead to capsize. That is wholly absent right now, and giving torpedos massive warheads or effortlessly slapping keels isn’t going to change that. Where ships take on water matters so much more than how much, or the explosive force of the torpedo, and Hit Points miss the point (lol) entirely. Modelling Longitudinal bulkheads and subdivided machinery spaces seems like the best way to model this weakness.

It was painful to read through this thread. There are more than enough people here who have read up on Naval Architecture, or failing that, can read and understand ship plans, to make solid and historically informed templates for the AI. RTW does a great job scaling designs by AI nation, and technology. We could very easily do the same here, and the game would be much better for it.

Given the German’s handling of radar… lol I wouldn’t place a lot of confidence in that. Information management as a whole in German surface ships seems to have been subpar. Even during the Channel Dash, which was doubtlessly operationally successful, on the tactical level I’m not convinced anyone on the bridge of a given Kriegsmarine ship knew what was going on.

I know this discussion is about Torpedos, but @Nick Thomadis - the higher hit rate is what is causing issues for every step of the line down! Ships have to be armoured and gunned entirely differently than they would be in reality because engagements are so different! I digress, but you can very easily test this by using approximately the same ship in UA:D, Jutland Pro and RTW 2. During the battlecruiser exchange at Jutland the British scored 11 hits iirc. They would easily get 100+ in the same conditions in UA:D right now. That means any sensible person would have to put 16 inch guns and vastly more armour on the German battlecruisers. To return to the problem at hand, is it possible that in this instance sonar acted more like a primitive RWR, or IRWR - only indicating that there was a launch, but not range or bearing? From what I know of German sonar arrays, that seems more feasible than plotting the torpedo. It would also still be useful in game and prime players to look for visible tracks. I was reading about Tactics in 1912, I’ll look for the passage later, and it said that evasive drills were taken if torpedos were suspected to have been launched. Of course at the ranges torpedos could reach by 1910, you couldn’t see the shot leave the tube, and I think trails were weak until more advanced torpedos came along, but the idea was to turn towards the bearing of the launch, so that you would pass through the “rake”. It could be as easy as telling players “if you think a torpedo has been launched, turn directly towards or away from it”, having sonar alert players to launch would just help them know to take evasive action, not tell them exactly when and how to evade by accurately plotting the torpedo in the water.

Lol anyone who thinks speed alone gave protection to Battlecruisers has been reading a book called “A History of 1st Battlecruiser Squadron: 1913 - April 1916”

For sure. I think the difference between rivet counting accuracy and more simplified authenticity is presenting the same dilemmas, choices and solutions present in history, through gameplay. It’s about feeling right, if you know what I mean. The example of this I am most proud of our feedback meaningfully guiding game design is capital ship secondary armaments. A lot of people seemed to believe these guns could, did and therefore should, hit and sink torpedo boats, effectively making capital ships wholly able to defend themselves from torpedo attack. Now, right off the bat, I could tell you a million reasons why that’s not true - and trust me we did! Accuracy and penetration tables, gunnery tests, accounts of surface actions, all pointing out the minuscule chances of a 3,4 or even 6 inch gun wholly disabling a torpedo boat or small destroyer before entering torpedo range. It seemed just about impossible to convince people that everything they thought they knew (cough WOWS cough) was wrong. But I think it was by reframing it in terms of authenticity that was convincing: - There needed to be a reason for players to choose destroyer and cruiser screens and - There needed to be a reason to include the cost, weight and crew of a secondary battery on capital ships It was making the case that making attacks riskier (a 1-3% chance of being hit is still going to give you pause before putting your life on the line), and more difficult under fire, rather that accurately hitting, let alone sinking torpedos boats, was the main reason for secondary batteries. A deterrence value, in other words. Effective protection - if deterrence was not enough, and at night, poor weather, low visibility or if the ship was otherwise engaged, or against a determined or desperate attacker it wouldn’t be - required a screen. Ultimately, I’m with you in that in a perfect world @Nick Thomadis would just call up the guys who made Jutland Pro and give it a 2021 facelift with ship builder, but that’s not the only way. All of that to say, I would gently suggest giving @Nick Thomadis a suggestion for gameplay reasons why the difference between coincidence/stereoscopic rangefinders matters. Okay, the historically accurate choice was not between aiming faster and being more accurate, I understand that, I’m sure Nick does too, but how can the player authentically experience the distinction? What’s the simplest way you could explain it to someone who knew nothing about range control, to say nothing of optics? There was a passage in Rules of the Game, I believe Chapter 7: The Battlecruiser Duel, that goes into it. Maybe you could pull from that? I recommend reading the book and taking notes, in examining decision making at Jutland it seems ready made to provide ideas for gameplay.

Let’s hope not. There has been a lot of really fantastic feedback here from people like @akd, @Steeltrap, @Draco, @ColonelHenry and others pushing very hard to ensure accuracy, and @Nick Thomadis has been pretty receptive to that feedback, especially in the past year or so.

Could you elaborate on that so I know what I’m looking for? Is this mostly placement points, or something else?

That was a great write-up. I said earlier that contre-torpilleurs, and the Italian ships built to counter them, were not interchangeable with other nations’ destroyers, and that seems to be a good explanation of why. To reiterate @ColonelHenry and @Draco’s point - I think ships like that have their place, but only if their many disadvantages do too. Without the many and varied downsides, of course the AI will build destroyers that match or exceed the contre-torpilleurs, why wouldn’t they?!

Lol that I’m a defence professional working in defence who reads professional sources?

@ColonelHenry and @SonicB said it better than I could, though @akd and @Steeltrap have said much the same before too. The AI designs ships poorly in both concept (9 gun destroyers) and execution (9 gun destroyers that explode in a stiff breeze). The defence of the poor AI ship design seems to be coming from players who also design, what I will call poor ships, but you can call fun, innovative, meme, super, I don’t care. To understand why the designs the AI is churning out are unacceptable requires understanding why ships were designed as they were, and that seems to be too onerous for some. That’s fine! The game allows for trial and error - but understanding what constituted error is why historical ships emerged as they did, and why the designer should aim for historical ships. We want the AI to build ships well, and therefore the best way to ensure that is defining what “well” looks like for it. It’s the exact same process that happened in history, but we don’t want the AI producing error after error, we want the AI skipping that intermediary step and building ships as if the AI represents a competent naval board and shipbuilding industry. Put another way, the current situation is as if the only ships encountered in Age of Sail were the Vasa, the Mary Rose, and Santisima Trinidad.

@arkhangelsk, I appreciate your reply and how you’re engaging with my arguments and sources. Below is a short list of the texts I have read to provide feedback for the game: Naval Firepower: Battleship Guns and Gunnery in the Dreadnought Era Norman Friedman Empires in the Balance: Japanese and Allied Pacific Strategies to April 1942 Willmott, H.P. The Naval Warfare of World War II: The History of the Ships, Tactics, and Battles that Shaped the Fighting in the Atlantic and Pacific Charles River Editors Jutland: The Naval Staff Appreciation Schleihauf, William The Rules of the Game: Jutland and British Naval Command Gordon, Andrew The Grand Fleet Brown, D.K Fleet Tactics and Naval Operations (Ret. ) Capt Wayne P. Hughes Jr. German Battlecruisers of World War One Staff, Gary DREADNOUGHT GUNNERY AT THE BATTLE OF JUTLAND FIRE CONTROL AND THE ROYAL NAVY 1892-1919 (Cass Series--Naval Policy and History) by John Brooks Royal Navy Strategy in the Far East, 1919-1939 Preparing for War against Japan (Cass Series--Naval Policy and History, 22) by Andrew Field Austro-Hungarian Naval Policy, 1904-1914 (Cass Series Naval Policy and History) by Milan Vego Prelude to Dreadnought John Winters Nelson to Vanguard Brown, D.K Warrior to Dreadnought Brown, D.K Struggle For The Middle Sea O’Hara, Vincent Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941 David C. Evans I would just say, because they are the prolific experts, any book by D.K Brown, Norman Friedman and Vincent O’Hara British Cruisers of the Victorian Era Friedman, Norman Osprey New Vanguard titles Angus Konstam et al Fighting the Great War at Sea: Strategy, Tactic and Technology Norman Friedman Before Jutland Goldrick, James Warships of the Great War Era: A History in Ship Models Hobbs, David Rebuilding the Royal Navy: Warship Design Since 1945 D. K. Brown Sunburst Peattie, Mark R. Dreadnought, Britain, Germany and the Coming of the Great War Robert K. Massie Neptune's Inferno James D. Hornfischer Avalanche Press articles: http://www.avalanchepress.com/line_WWIISea.php

lol seeing as you discounted pages and pages of relevant quotes from texts on the subject as "irrelevant" I can see how you'd think that. Unbelievable. I'll buy you a copy of Brown's books, because so far as I know your perspective on naval architecture is coming from paddle boats. You tell me the fundamentals of good ship design, and I'll show you where the AI falls short. Since you seem unaware or apathetic of qualities like top weight, stability, seakeeping, or any other constraints of reality, I don't know how better to explain to you why these designs fail. I apologize for being short with you, but honestly - you're writing off academic sources to prattle on about what feels cool, there's no way for me to address that.

All you would have to do is skim any of the historical studies that are incessantly linked in these threads to see that navies of all nations realized that the ballooning cost and size of warships were causing tremendous difficulties for their building programs: This game is not just about building ships in the abstract - the strategic layer is about fleet building programs, not individual ships. If the AI designs ships that will bankrupt their nation, or are impractical, or have no doctrine that provides them with worth, then they are badly designed ships. Full stop. A designer that trends towards badly designed ships is not working. It's obscene to point to the largest most heavy gunned designs and smugly say "See? Destroyers weight 2000tn and have 12 5 inch guns."

It's a little disingenuous to present contre-torpilleurs and their Italian counterparts as "typical" destroyers, especially to argue that AI of every nation building heavily gunned, large displacement warships in 1910 is in any way excusable.