"Unrealistic firing ranges" Topic

Young Henry is smug enough with his gunnery without encouraging him further ;-)

I'll try to stick with the topic here. Excuse me if I'm redundant or cover material in a previous post. I'm mainly discussing WWI range finding and gunnery. This information is from memory but mostly from David Campbells's book on Jutland, Bill Jurens and John Brooks book on naval gunnery at Jutland. My numbers should be pretty close.

Being able to spot your enemy and get a shot off first at extreme range is a big advantage even though the chance of a hit at max range is zero. I'll try to explain why.

For the example we'll use excellent sighting and environmental conditions for spotting. First you have the variables of spotting (spotting height, target and firing ship heights, environmental conditions). You'll most likely spot the enemy smoke while he is below the horizon before sighting the actual ship. This gives a slight advantage to ships with stereoscopic range finders to start building up a firing solution as I'll explain below. Whoever sights first starts building up a firing solution to start firing ranging shots with no expectations of a hit.

Next you have to build up some type of targeting data for range, speed and course using your range finder and other visual aids (no shooting yet) with the advantage going to who sights first. The more range finders giving input the more accurate your results will be. Stereoscopic rangefinders can focus and take readings on things like smoke and somewhat obscured targets. Coincidence range finders need a good clear target image to take a reading. Coin range finders will normally have to wait until the majority of the target is above the horizon (at least mast and funnels) before it can start taking readings. This means a ship with stereoscopic range finders can have a 1-2 minute advantage in building up a firing solution than a ship with a coincidence range finder.

If two ships spot each other with all other things being equal the ship with the stereoscopic rangefinder should get the first shot off. Other factors would be how they perform plotting from the range finders. Each rangefinder reading will help determine the targets speed and course. A range finder can take about 10 readings a minute at short ranges and 2-4 at extreme ranges under ideal conditions. This is why it takes a few minutes to even have a slight idea of a gunnery solution to use. In WWI the Germans had stereoscopic rangefinders and a system that was a few minutes quicker than the British in the opening minutes of a battle. The British coincidence rangefinder and plotting system had advantages as the battle progressed but we are only discussing the opening shots here.

Here are some of the problems in a long range gunnery solution: About the best accuracy a range finder will deliver at 15-20000 yards is going to be 15-20 mil or at 15000 that's an error of 225 to 300 yards. At 20,000 yards that's 300-400 yards. Estimating errors for the course and speed will add to this error. At 18,000 yards you could have a 30 second time of flight with the target moving about 250 yards at 15 knots. If you estimated the speed at 18 knots the ship would have moved 300 yards. 50 yards may not seem like a lot but if a salvo landed 50 yards in front of a battleship sized target even if the range was good enough to straddle there's a good chance for a lateral miss on all rounds and at long range the spotter not being able to determine if the MPI was short or long making the shooting results worthless for correcting. Throw in another 10-30% error for poor equipment calibration, human error, miscommunication, plotting room mistakes, etc and you can get an idea of the gunnery solution challenges involved and why firing a full salvo at extreme range as soon as sighting a target without building up a firing solution is pretty worthless and a waste of ammo. I'd say less than 1% chance.

The bottom line seems to be that the quicker you built up a fairly good firing solution to get off a single or ladder ranging shots the quicker you'll be able to correct to start firing full salvos and correct them to get a straddle. There was no expectation of a hit with ranging shots. The ability to get off one or two full salvos after ranging shots before your enemy is a huge advantage. From what I've read about Jutland both sides could expect a straddle at long ranges after 2-3 full salvos but only after consecutive ranging shots produced an over and under to get a good enough idea of the range and validate the firing solution in the plotting room. This entire process of building a good firing solution and firing multiple ranging shots could take 5-10 minutes starting at extreme range. The advantage of opening fire first is being able to straddle first. Targets maneuvering or taking evasive action complicates things because the firing ship will not notice these changes right away giving the defender an advantage to evade a straddle. This is why chasing salvos can work.

If your game turns are 5-10 minutes in length you will have to do a lot of abstraction and die roll modifiers to get this level of detail. Personally I feel that in games that are about simulating gunnery officer duties you need one minute turns. If your game simulates being a fleet commander the above is not worth while integrating into the game but you might want to have some type of a routine that allows one side or the other to start firing full salvos before the other based on sighting and fire control equipment and techniques.

Thanks,
Wolfhag

Most of the better rules (GQ 3.3, Seekreig and CaS come to mind) have some of those factors in their CRTs. I know GQ1/2 doesn't (but then the rules are 35+ years old; before a whole lot of research had been done on the subject).

I doubt the more recent rules sets are much more accurate on fire control than GQ1/2. In my experience the difference is usually more (and frequently incorrect) detail, as I discussed in another thread several years ago. The motivation for making such statements is presumably either to sell rules which one has a financial interest in, or to increase the opponent base for a favorite rule set.

In any case, adding such detail to a simpler rule set is not difficult. For example, I see that GQ3 has negative die role mod when the firing ship changes heading by over 30 degrees. This could be directly transferred to GQ1/2 (with the modified D10 straddle table). Other, more original, "to straddle" die roll mods would be equally trivial to add, (representing either single factors, or groups for the less significant factors).

Mark H.

Interesting… The listing for this thread does not show the updates for April 19th, either in terms of the date, or in terms of a "bump". Is this a new bug?

/mivacommon/boards/topics.mv: Line 581: MvUPDATE: Runtime Error: Record is not in index /mivacommon/boards/topics.mv: Line 581: MvUPDATE: Runtime Error: Record is not in index

MH

I was just wondering; as the first shots are ranging shots, is it that the timing of 'open fire' relates to the time the ship commenced firing for effect, or when the first ranging shots were fired?

Personally I feel that in games that are about simulating gunnery officer duties you need one minute turns.

One minute turns may give an illusion of increased accuracy, but actually suffer their own simulation problems (e.g., a shooter who can get off a salvo every 26 secs should shoot 4 times for every 3 shots by a shooter who can only manage one every 34 secs, but both round off to 2/min), and vastly increase the mechanical burden on players with deleterious distractions. It seems like poor game design to make players who care most about gunnery operations stop every shot or three to move, turn, resolve a tiny increment of progressive damage control operations (fires, flooding, engine repairs, turret repairs), and so on.

Has anyone done a gunnery-focused game that abstracts squadron operations, ship moves, damage control, etc. into a longer-period turn (e.g. 5-10 mins) but resolves gunnery in multiple rounds per turn? It seems like this ought to be doable by regulating movement with a low-resolution grid (e.g. 6000yd squares) or multi-minute ship moves across the gaming surface (5, 6, 10, 15, whatever), and resolving gunnery in multiple rounds per turn. I'm not really a "gunnery guy", so I'm unfamiliar with the genre.

If your game simulates being a fleet commander […] you might want to have some type of a routine that allows one side or the other to start firing full salvos before the other based on sighting and fire control equipment and techniques.

That's a very interesting idea. I might like to try something like that. If anyone's tried it, I'd love to know how it was done, and how it worked out.

- Ix

Has anyone done a gunnery-focused game that abstracts squadron operations, ship moves, damage control, etc. into a longer-period turn (e.g. 5-10 mins) but resolves gunnery in multiple rounds per turn?

Seas of War has 2.5 minute turns.

One flaw of "Cordite and Steel" rules is that salvos can be done with arbitrary tightening of shell spacing. There is the problem with shell dispersion, they will scatter. For example I have the firing tables of the German 88mm FlaK and Russian 122mm A19 guns. When firing at 14,500m or 15,800 yds the 88mm will have a standard deviation dispersion of 98 yds and the A-19 will have a standard deviation of 104 yds. You can't tighten the salvo any more than that, even if you try to aim all guns at the same spot.

"I doubt the more recent rules sets are much more accurate on fire control than GQ1/2."

Well, the newer rulesets do benefit from the wealth of material that has come out since GQ1/2's publication back in the mid '70s. And that's not my opinion; that's the opinion of the author of GQ1/2.

As for having an interest in one set of rules over another: I could care less what somebody plays; whatever it is, if it fits their likes/dislikes, fantastic. I have my 'favs', you have yours and someone else has theirs. Its a personal decision and no more.

"I doubt the more recent rules sets are much more accurate on fire control than GQ1/2."
We should have a test!

Well, the newer rulesets do benefit from the wealth of material that has come out since GQ1/2's publication back in the mid '70s. And that's not my opinion; that's the opinion of the author of GQ1/2.

That's because the author of GQ-1/-2 is also the author of one of the "newer rulesets". I would expect him to prefer his latest creation for both aesthetic and financial reasons.

However, game designers are not the only ones who have access to the "wealth of material" you refer to, and thus there is plenty of scope for legitimate differences of opinion on gunnery rules. I own one of the "newer rulesets", and I don't think the greater detail has improved gunnery historical accuracy. Two examples off the top of my head:

1. In the newer ruleset, gunnery efficiency is now a function of gun caliber and nationality, rather than merely gun caliber. This includes questionable evaluations such as giving the British 15" gun (with a very accurate low-velocity, heavy shell combination) better performance than the German 15" (with a high-velocity, light shell combination). In any case, my reading of the history suggests that a better distinction would have been by fire control system. Shouldn't the AFCT Mk10 on Vanguard be better than the old Dreyer on Hood, both of which control the same 15" main armament? Friedman in the recent "Naval Firepower" thinks so. An example of more detail leading to less accuracy.

2. In the newer ruleset, the British quadruple 14" turret (many teething troubles) is more efficient that a contemporary triple turret, due to a new game mechanism using one die for each pair of guns on the broadside. This is an incorrect extension of a rules effort to reflect issues with triple turrets versus twins. Even the triple-versus-twin conclusion may be off, given that rate-of-fire issues are less important with actual firing rates, and given that navies worked successfully on improving interference issues with adjacent shells. Another example of more detail – less accuracy.

Mark H.

I'm not sure people have the mechanics of WW1 gunnery quite right. The Grand Fleet Gunnery and Torpedo Memoranda (a compendium of lessons learned over the course of WW1) emphasized several important facts learned over the course of the war: [1] the 9ft B&S range-finder had proved inadequate to its task and "the gun was used as its own range finder"; [2] plotting had proved a failure, due to the evasive maneuvering undertaken by German ships whenever straddled; [3] getting an accurate measurement/sense of target inclination relative to own ship was both essential and extremely difficult.

WW1 gunnery, as actually practiced, was a process of [a] getting on for line; bracketing to more or less establish the range; [c] use of largely guessed range rates (a function of target inclination and bearing relative to the firing ship) to "cross" the target. It was a rare thing to actually get the range rate correct for more than a moment of time.

digression – it is important to appreciate the complexity of "range rate". The rate of change of range could not be relied upon to remain a constant value, even if both ships were maintaining steady courses. One of the important functions of the fire control computer was to compute the rate at which the range rate itself was changing. In order to achieve an accurate result, it was essential to know the true target inclination – and this was a VERY difficult thing to accurately measure in WW1.

The end result was that good gunnery essentially relied upon good spotting. All the rangefinders, inclination measuring devices, and fire control computers could gain you admission to the theatre, but after that you had to "find your seat" on your own. Spotting efficiency generally relied upon the "sampling rate" – the number of salvoes that could be fired, spotted and corrected for within a given unit of time – which I have referred to in previous posts. Sampling rate fell more or less consistent with the increase in time of flight.

Also, use of single shot fire was a rarity, its use being confined to perhaps judging whether one's gun battery was in range of the enemy (as at Dogger Bank) when rangefinder readings could not be relied upon. All serious bracketing and spotting fire was done by salvo (preferably 4 shots). Only by use of a multi-shot salvo could the salvo MPI be judged in relation to the target; the fall of a single shot was far too random to be of any real use.

….. no idea where all the bold blue came from.

B

The bold started because you used brackets for your list points, and [b] means "start bold here". The easiest way to avoid that problem is to use an actual <ol> with <li> bullet points as explained in the FAQ.

I made the above [b] appear by inserting the HTML code for a backspace between the brackets and the "b".

- Ix

One of the ramifications of Blutarski's point is that a higher velocity gun will have a growing advantage as the range increases. That implies the higher-V, smaller caliber German guns had an advantage after all, at least in long range BC duels, for a reason nearly orthogonal to pre-war German reasoning.

Heh. Now I have a reason to look up the muzzle velocities of the guns of Mediterranean navies. Thanks!

If most ranging was actually done by feel (lobbing shells until a bracket is observed), how long could a "fire for effect" rate of fire typically continue?

- Ix

Heh. Now I have a reason to look up the muzzle velocities of the guns of Mediterranean navies. Thanks

It has already been worked out in the tables for Seas of War. It is called the DAF (Descent Angle Factor) number. It reflects on the size of the danger space for a range band. This has been worked out for almost every gun.
You're welcome.

One of the ramifications of Blutarski's point is that a higher velocity gun will have a growing advantage as the range increases. That implies the higher-V, smaller caliber German guns had an advantage after all, at least in long range BC duels, for a reason nearly orthogonal to pre-war German reasoning.

I am not clear as to how you reach this conclusion; he seems to be discussing WWI fire control, not ballistics. Could you elaborate, please? :-)

FWIW, my reading indicates that, all other things being equal, a moderate velocity gun with a heavy shell was considered to be be more accurate at longer ranges. In particular the RN and USN subscribed to this view. Not so much the Germans, though, but they were expecting combat to occur at shorter ranges. Note also that heavier shells retained their velocity better than lighter ones (what matters is striking velocity at impact, rather than muzzle velocity), which is one of the reasons why most navies, especially post-WWI, generally chose them for newer designs.

MH

a moderate velocity gun with a heavy shell was considered to be be more accurate at longer ranges.

Indeed it was thought that way. In fact because of the steeper impact angle the danger space is smaller thus the accuracy advantage is nullified. It's just the way the math works out.

I am not clear as to how you reach this conclusion; he seems to be discussing WWI fire control, not ballistics. Could you elaborate, please? :-)

My thought was:

Higher velocity =
shorter travel time to target =
less time between observed shell splashes =
greater rate of fire =
more opportunities per [period of time] to adjust range and get salvos on target.

Is there a car missing from that train of logic?

- Ix

In fact because of the steeper impact angle the danger space is smaller thus the accuracy advantage is nullified. It's just the way the math works out.

For a single shot, perhaps, but you are leaving out other pertinent factors. One which comes to mind is that one needed to fire multiple shells, in salvos, repeatedly, during an engagement. Various books in my possession (one example being "British Battleships", by Raven and Roberts) indicate that higher velocity guns were found to lose muzzle velocity more rapidly between shots, which adversely impacted accuracy during the course of an engagement. (This could have also affected salvo patterns, I assume). Furthermore, lighter shells were found to lose velocity during time of flight to a greater degree than heavier shells, which adversely impacted striking velocity at longer ranges. This was apparently the thinking both of both British and US (and probably other non-German as well) ordnance designers up through WWII, and this is reflected in the progress of their gun and shell designs.

Mark H.

My thought was:

Higher velocity =
shorter travel time to target =
less time between observed shell splashes =
greater rate of fire =
more opportunities per [period of time] to adjust range and get salvos on target.

Is there a car missing from that train of logic?

I guess I was responding sceptically to your "…implies the higher-V, smaller caliber German guns had an advantage after all, at least in long range BC duels…".

Perhaps you meant not an overall advantage, but rather an advantage in getting initial spotting feedback? Then your logic holds theoretically, but did it have a significant practical impact in reality? IIRC, up through Jutland, the Germans did have an advantage in initial ranging, but that was mostly due to ponderous British ranging practices, and to a lesser degree, better German rangefinders. I was under the impression that the improved British ranging practices used after Jutland cancelled much of or all of this German advantage.

I assume that Blutarski will comment on my impressions. I am too lazy this evening to search through my books.

Mark H.

Well, yes, there is a missing car in your train of logic. While the time of flight is shorter, the amount gained is negligible (time of flight to 20000 yds for the German 15"/52 was 32 seconds while the British 15"/42 was 32.5 seconds with an the angle of fall of 16.4 and 18.3, respectively).

The one big factor in favor of medium velocity guns over high velocity guns was barrel life. The German 15" (2690 fps) had a barrel of 180-210 rounds while the British 15" (2400 fps) had a barrel life of 335 rounds. Something to consider from an operational point of view.

The major constraint on rate of fire was the reload cycle. Depending on the design of the mount, that could range from 45 seconds to 30 seconds (although the Germans claimed a rather optimistic 20 seconds for their 15" mount).

And Mark has the right of it re: WWI practice. IIRC, the Germans were an early adopter of the faster 'ladder' method of ranging while the British came to it later (post Jutland?). Gave a substantial advantage to the Germans during the early war battles.

"That's because the author of GQ-1/-2 is also the author of one of the "newer rulesets". I would expect him to prefer his latest creation for both aesthetic and financial reasons."

Mark- Oh please… NOBODY is in the rules writing game to make money (cripes, Bangladeshi shoeshine boys make more). If you believe that everyone who writes rules has the goal of using their 'vast' royalties to retire to Cabo and sit on the beach sipping maggies all day, then you have a very flawed understanding of the hobby business.

At bottom, a ruleset is an interpretation by the author of the available data, doctrine, etc. If you agree with author's interpretation, then you'll love the rules. If not, you'll hate them. And differences in interpretation aren't reserved to gamers and rules authors (not hardy!). I recall a particularly nasty debate some years back between two professional historians regarding WWI fire control. So differences of opinion are going to be the standard, not the exception.

Like I said before: If a ruleset fits your likes/dislikes, fantastic. If not, go find another set that does (and there are whole bunch to chose from).

Coastal2,

Let's not stray from the point of our discussion by inserting red herrings.

You suggested that Mr. Gill prefers the GQ-3 gunnery rules to his previous GQ-1/-2 version. I can believe this, for the reasons stated, which incidentally would also apply to me if I were a published rules author. No personal criticism of Mr. Gill is implied or intended, nor does it lessen my admiration for those who provide our hobby toys for us, for minimal financial return.

However, his preference does not by itself make the later gunnery rules more historical than those in GQ-1/-2. This is not necessarily a criticism, as the original General Quarters system in GQ-1/-2 was a brilliant achievement, and still is 35 years later. I happen to prefer it over the later GQ-3, but either is an excellent purchase decision, and I have always tried to make this clear in my posts. So there. :-)

Mark H.

….. The issue is not so much muzzle velocity as it is retained velocity downrange. For any given projectile shape, the greater the caliber the more ballistic efficiency it possesses. Why? Cross-sectional area varies as the square of projectile diameter, while projectile weight varies as the cube of the diameter – combining to make a denser air penetrator per unit of cross-sectional area.

In classical exterior ballistics formulae (Sciacci, for example), C (Ballistic Co-efficient) is typically expressed as -

W
---
cD^2

- where W = projectile weight, D = projectile diameter, and c = the co-efficient of form (typically signified as a value < 1.0, where a lower value = a "slipperier" projectile). The higher the value of "C", the better the ballistic characteristics of the projectile and the less velocity is lost per unit of time as the projectile travels through the atmosphere. If you keep "c" constant, a little experimentation with guns of different calibers will show up how dramatically ballistic efficiency improves with increase in gun caliber.

Navweaps lists downrange retained velocity data for the British WW1 12/50(850lb), 13.5/45(1400lb) and the 15/42(1920lb).

The muzzle velocities of these three guns are respectively:
2852 f/s – 2491 f/s – 2467 f/s

At 15,000 yards, the retained velocities are:
1495 f/s – 1487 f/s – 1537 f/s

At 20,000 yards, the retained velocities are:
1302 f/s – 1332 f/s – 1377 f/s

By 20,000 yards, the 12/50 has lost 1550 f/s, the 13.5/45 has lost 1004 f/s, and the 15/42 has lost 930 f/s.

B

20,000 yds for the German 15"/52 was 32 seconds while the British 15"/42 was 32.5 seconds with an the angle of fall of 16.4 and 18.3, respectively).

You probably are referring to Campbell's Naval Weapons book but you have mixed meters with yards.

The angle of fall at 20,000 yds of the British 15" 4crh shell was 22°15' and 6crh was 18°20'. The German 15" was about 14°30'. Time of flight would be about 29 seconds.

"The angle of fall at 20,000 yds of the British 15" 4crh shell was 22°15' and 6crh was 18°20'. The German 15" was about 14°30'."

….. In terms of danger space relative to a 30ft tall target, that represents a danger space of 39 yards for the German gun versus 30 yards for the British 6crh gun and 24 yards for the 4crh version. Beyond 8-10,000 yards with a heavy caliber gun, danger space was a fairly minor consideration.

B

Let me run this by everyone. If you have a firing solution that generates a 10% range error at 20,000 yards that would be a +/- 2,000 yards. If you decide to start firing ranging shots you'd want to make sure the first shot is short so that it can be observed. You probably have the first round ideally land 2,500 yards short. Spacing ranging shots 800 yards you'd need to cover 4,500 yards to ensure a consecutive under and over so dividing 4,500 by 800 means about a 17% chance to straddle with each ranging shot. With a time of flight of about 30 seconds and taking 10-15 seconds to communicate and update plot and firing information you'd be getting a shot off every 40-45 seconds. So you should get a consecutive under and over ranging shot within 4-5 shots or in about 2.5-3.5 minutes. Add that to the 3-5 minutes time spent performing range finding data to build up a firing solution you are looking at 5-8 minutes from initially spotting a target. That under pretty much ideal conditions.

Once you've straddled with 800 yard ranging shots you've narrowed the range error down to about 800 yards. Firing a 400 yard length salvo gives a 50% chance to straddle. Let's say you straddle the target with an 8 round 400 yard length salvo being spaced one round every 50 meters (I know they'd not be exactly 50 yards). If the danger space is 35 yards you'd have a 70% chance of having one round hit. If you straddled with an 8 round salvo with a 200 yard length salvo rounds would be spaced every 25 yards. With a 35 yard danger space that should give a 100% chance for one hit and a 40% chance for a second hit. If the danger space was 50 yards you'd have a 100% chance for 2 hits and 0% chance for 3+ hits. If you straddle there should be one or more near hits that could cause splinter and concussion damage too.

So would there be a way to abstract the amount of time from initial spotting to shooting full salvos? Would that still be playable and realistic enough? That's how I see it but I'm doing this at 4:30am.

Wolfhag

I should make some clarifications. The 35 yard danger space should include 30 yards of the beam of the target making the "Hitting Space" 65 yards. So for an 8 round salvo 400 yards in length should have one hit plus a 30% chance for two hits and 0% chance for 3+ hits. That would be for a target perpendicular to the firing ship. You'd need to have some type of modifier increasing hits the less perpendicular the target is. I guess if you crossed the "T" of a target 200 meters in length you could expect about 3-5 hits with a 400 yard 8 round salvo plus 1-3 near hits.

I've looked at Seas of War charts and it seems to use some type of formula and die roll modifiers that simulates the above.

Correct me if I'm wrong.

Wolfhag

The 35 yard danger space should include 30 yards of the beam of the target making the "Hitting Space" 65 yards.

That's the way I see it. But I throw in the shell dispersion to make it less of a sure thing.

I've looked at Seas of War charts and it seems to use some type of formula and die roll modifiers that simulates the above.

binomial distribution
But as it is a 2.5 minute turn so it covers more than one salvo.

The devil is always in the details and so it is with estimating likely hits out of a salvo. Some things to think about (as they relate to WW1 gunnery)-

1 – If the average spread of a four shot salvo was 400 yards, the average spread of an eight shot salvo would be approximately 50pct larger (600 yards). What was really important to know was the mean error of the gun/projectile combination at the range of interest.

2 – Binomial distribution (2\7\16\25|25/16/7/2) over +/- four mean errors is a "law" only applicable to very large numbers (100's or 1,000's) of samples. For a very small number of samples (like four shots of an individual salvo) there is no guarantee that the fall of shot is going to be so neatly distributed. A little time with some graph paper and dice will demonstrate the fact. When the component shots of the salvo display an eccentricity in distribution, so does the mean point of impact (MPI) of the salvo deviate from the aim point; +/- 50 or 100 yards would not be surprising. Salvo MPI deviation is an important second order component of mathematical analysis of likely hitting rates.

3 – The general rule of thumb for a spotter was to maintain salvo fall of shot in a manner such that half the shots would be seen to fall short. At battle ranges, where it was impossible to judge by eye or optics the error in range between the (somewhat wandering) MPI of the salvo and the target ship, keeping half the salvo short as splashes was the best way to be reasonably confident that some portion of the 50 pct zone (+/- one mean error) was covering the target.

4 – Let's consider the likely result with:
(a) point of aim perfectly situated at the waterline of the target ship perpendicular to the line of fire.
(b) a four shot salvo with a mean gun error of +/- 50 yards.
(c) target ship of 90ft beam and 30ft height.
(d) an angle of fall of about 15deg (37yds danger space).

With roughly a 1 in 3 chance of any given shot hitting, by my reckoning there is an 80pct chance of at least one shot hitting, about a one pct chance of all four hitting, and a 20pct chance of none hitting.

Offered strictly as food for thought.

B

50 pct zone (+/- one mean error) was covering the target.

Actually in a Gaussian distribution the 50% zone is not +/- one mean error, though related they are two different things.
At about 14,500 meters (15,800 yds) the mean error for two guns I have long range firing tables for is about 79 yds. If this was proportional to the error at 20,000 yds it would be +/- 100 yds not 50 yds.

How does all this accuracy square with ease of play. Which is what sells games.

Some people just write rules for the fun and challenge of it and don't sell anything. There's a lot of easy play "Roll a '6' and Sink the Bismarck" rules that have been written. I don't know if they sell any better than uneasy play rules.

For what it is worth when writing my gunnery rules I based the chance of hitting on a cumulative normal distribution with 2% chance of a hit at maximum range and then a binomial probability for the number of "hits". These figures were then combined into a single percentage dice roll speed things up. (I'm not a "buckets of dice" player)

The figures work out to make it pointless to fire a small number of guns at long range unless as ranging shots. This can be especially valuable if a player can make an accurate judgement as the range is decreasing: skilfully ranging for a turn at extreme range, then full salvo firing as the ranges drops into the next band.

I don't claim that the results are 100% accurate, and I have a second gunnery table, with higher hit rates, for optional use when playing with beginners as they prefer the damage to mount up more rapidly. The method gives fairly realistic results, especially when combined with rules to encourage players to preserve their ships rather than throw them away in do or die missions.

CampyF,
As far as ease of play I guess it depends on what you want to simulate in a game and how detailed. The other important thing is what kind of an experience does it deliver and what risk-reward decisions can the player make. For me I want to consider to a greater or lesser extent the factors affecting a detailed gunnery model and a chance for player risk-reward decisions rather than being a random number generating spectator. A game that delivers somewhat historical results but uses generic or Warhammer 40K mechanics does not deliver the experience of a naval battle for me. If it does for you use it.

Blutarski's last post has some good suggestions and ideas. Remember, the first real analog computers were used to solve gunnery problems. Abstracting that to "ease of play" using traditional game mechanics and still have a good feel and experience to the game is hard to do with so many variables for every shell fired it's impossible to duplicate reality.

Someone asked about 5 minute turns. Personally I think that's too much to abstract because that can equal an exchange of about 5 salvos and any one salvo has the potential to cause a catastrophic explosion. A detailed and historically accurate gunnery system needs to take into account the firing and results on a salvo by salvo basis. That's my opinion. You need to find a balance between a detailed gunnery system and a large battle. That's hard to do and won't please everyone.

Hitting at long or medium range is going to be pretty much the same process and use the same mechanics. The opening phase of the battle involves gathering fire control data. A risk-reward decision for the player would be to open fire sooner but having a lesser chance of a straddle. Taking longer to gather firing data would result a better chance of a salvo straddling but may give the enemy the initiative of getting the first full salvo off. That could be an "order" to open firing salvos at a certain turn in the future after spotting putting some FoW into the game as you would not know your opponents decision. So when it's the turn to open fire you could roll to randomly determine the base accuracy for the first shot depending on the number of turns spent generating firing data.

The next risk-reward tactic would be the players decision to fire tight or loose salvos (length) with some restrictions on the ships fire control, gun accuracy, director control, visibility, etc. A loose salvo would have a better chance of a straddle but lesser chance of a hit or multiple hits. Firing a tight salvo would have a lesser chance of a straddle but if it does straddle there is a greater chance for a hit or multiple hits. Then you need to determine the chance of a straddle on the next salvo which would be some type of modifier.

Maneuvering is very important and I think that is too abstracted in most game systems. In WWI most turrets in battleships could rotate from 2-4 degrees per second. Any real evasive maneuvers that would get you out of straddles would most likely destroy your current firing solution and the rate of turn and heeling over would mean you would not be able to fire back until the ship straightened out on an even keel. This gives a big initiative to your opponent and would probably let him get off two salvos before you could start firing again.

Depending on your game system you'd most likely be using die roll modifiers to implement any of the ideas in this thread. Personally I like systems based on some type of a formula/binomial using charts rather than a magic "to hit #" with various die roll modifiers but modifiers are always going to come into play.

Seekrieg IV and Seas of War has a system for hit probability taking into account fire control types and other variables that is not just a "to Hit" number. They both give a good feel for naval gunnery. There are probably others but I'm not doing a review of all games but both of them are free. If you are looking for real ease of play that includes most aspects of naval warfare as die roll modifiers I like GWaS system but using a D6 means not much room for other modifiers.

Wolfhag

Thank you Wolfhag. I actually purchased Seekrieg 4 some years back. It is incredibly detailed in more than just fire control. And very well done in general. Just started looking at Seas of War. Generally, I prefer larger battles, playing solo. My current is the evacuation of Wake island, with task forces around the Enterprise and Lexington, arriving about the same time as the Hiryu and Soryu group. Unless you have a great deal of time to devote, they are not exactly conducive to my type of scenarios.

Lately, however, I have been looking at smaller scenarios, mainly first world war. Just with von Spee, you could have battle with the British China squadron, the Australia and company, and even the Japanese.

Thought of giving the Blucher with a light cruiser the job of guarding one of the German African colonies. Two or three British armored cruisers and a couple of light cruiser, see what develops.

As for wargamers firing at ridiculous ranges, I will point out that the Japanese cruisers at the Java Sea opened fire at 28,000 yards.

I hope to have time to try out Seekrieg again

For what it's worth:

In Norman Freidmans's book "Naval Firepower: Battleship Guns and Gunnery in the Dreadnought Era" he discusses the British debate between opening fire at long range or around 10,000 yards where enemy destruction could be assured in short time. The problem was the British fear of German torpedo attacks at the shorter ranges needing a way to open fire at max spotting range. At the time of Jutland the Grand fleet Battle Orders called for opening fire (ranging shots?) at 15,000 yards and staying no less then 14,000 yards until the enemy is battered and then moving to 10,000 yards to open with rapid fire to destroy them.

After Jutland orders were for 12 inch guns to open fire at 1,000 yards beyond their maximum range as long as the range was closing.

The British also felt that in poor conditions of the North Sea rangefinders may not work but spotting and correcting salvos could overcome this at maximum sighting ranges. At Jutland the Germans were opening fire before the Brits which forced them to open fire too. It looks like in practice both sides saw the benefit of opening fire at maximum sighting range.

At maximum ranges of most guns the salvo length would be 400-600 yards with an angle of descent of 30-35 degrees. The Hitting Area of a battle ship at that range would be about 35-40 yards. I have not done the math but I think this would translate to about a 30-50% chance of one hit if straddling with an 8 round salvo but most likely a deck hit. That's an estimate but you get the idea.

Wolfhag

….. Spot on as regards British WW1 battle doctrine in terms of engagement ranges.

A point of interest – In conditions of limited visibility, GF doctrine was to immediately open fire upon any new enemy target, without waiting to either generate a plot or even take any range readings.

As far as the Germans opening fire first at Jutland, this only really occurred in the BC action and, IMO, was a consequence of a conscious decision on Beatty's part to allow the range to close (so long as the Germans themselves were withholding their fire) to a really effective range. Speaking strictly in terms of gun ranges, Beatty's 13.5in BCs handily outranged all the ships of Hipper's 1SG. One of Beatty's comments post-Dogger Bank (IIRC) was that long range fire was all well and good, but could not be decisive due to the materially reduced rate of hitting coupled with limited ammunition supplies. Beatty was seeking decisive results and that could only be obtained at shorter ranges.

B

The Germans fired in ladders to get an approximate range.

So here is one way to handle long range fire:

As soon as you sight the enemy you start gathering fire control data and firing spotting shots before firing full salvos. The amount of time (number of turns) spent modified by crew expertise, environmental factors, target maneuvering and firing platform factors determines the initial ranging error which is from 5%-15% (somewhat subjective) and up to 20% under poor environmental conditions at long range. Also firing ladder ranging salvos is about twice as quick as single ranging shots. Before determining the error the player selects the length of the salvo which the minimum is determined by the firing platform gunfire control and gun accuracy. There is a rules based minimum salvo length but the player can select a larger salvo length. The best way would be for an umpire to hide from the players the true ranging error because in reality you never know.

Example: True range is 20,000 yards. Base Ranging Error is 15% which is 300 yards which I guess can be randomized in a bell curve and be from 150 yards to 450 yards with 2/3 chance being 300 yards. If the salvo length of 8 rounds is 400 meters the MPI is at the ranging error which for the example is 300 yards and is short (gunnery officers always tried for short salvos as long may not be spotted). So the result of the salvo is the furthest round in the salvo (closest to target) lands about 50-150 yards short. All rounds miss.

The next step is important and hard to recreate in a game. Depending on environment conditions and smoke interference the people in the spotting positions of the firing ship may spot the salvo as short, straddling or may not spot it at all. High speed vibrations from the firing ship, splashes from near hits, and vibrations from enemy hits, smoke stack interference and environmental conditions prevent perfect spotting. Spotting the salvo short (or even straddling) the correction may be to add 200-400 yards for the next salvo. Umpire generating FoW makes the process interesting and puts more decisions on the player than charts and die rolls.

So if the firing and target ships cooperated by not changing course and a correction of +200 means a ranging error of -100 yards so the MPI of the 400 yard salvo is 100 yards short which results in a straddle. With each of the 8 rounds spaced 50 yards apart and a hitting area of 40 yards means about an 80% chance of one hit and no chance for multiple hits.

So after firing salvos spotting the results is more important than range finding. Good range finding will generate a good range keeping plot but you still need to sight the target to update the plot.

Wolfhag

One problem, 15% of 20,000 is 3,000 not 300.

Ouch! I hate it when that happens and I don't think it's the first time. I was transposing numbers between mils and % and didn't check final numbers after deciding on using %. Changing % to mils should make sense out of it. Thanks Mobius.

Wolfhag

I thought Naval Thunder had an elegant way of combating the problem: you tick a mark for every salvo fired at extreme range that missed. Each tick was worth some number of victory points to the opponent. This allowed for ammunition restrictions to play into one off games without restricting those who want to go hog wild on low percentage, extreme shots.

Had a chance to unearth a WW2 circa 1944 document addressing anticipated hitting rates for US BBs at various ranges.

The following data reflect radar FC and a capital ship target at 90deg broadside to line of fire.

15k yards – 10.0 pct hits
20k yards – 5.0 pct
30k yards – 1.5 pct
35k yards – 1.0 pct

These values are consistent with the general sense that fire beyond 20,000 yds rapidly becomes quite unprofitable and by 30,000 yds could arguably be deemed as random fire.

B