Archive for the ‘WWI’ Category

Course Calculation for Constant Range – 1913

December 22, 2017

In October 1913, Chatfield (Beatty’s flag captain) wrote a memorandum entitled “Fast Division Work from a Gunnery Standpoint” (The Beatty Papers Vol I, Item 49, page 90). This memorandum included the following statements about changes in gunnery range:

“… the attempt to obtain a tactical, or rather a gunnery advantage, usually results in a high and frequently changing rate due to constant change of course. This must affect the gun fire, possibly … to such an extent as to entirely neutralize the value of the position gained.”

“… it is quite easy, with superior speed, to calculate suitable courses which will keep the range constant and the rate nil …”

“The T must never be crossed at too broad an angle as this is unnecessary and causes a big and difficult rate.”

Two examples are given in the memorandum for a fast division speed 5 knots greater than the enemy. Both are apparently wrong and were corrected in notes added by Beatty. Also, specifying only the difference in speed is insufficient. The solution for 10 knots and 15 knots (for example) would be significantly different from the solution for 20 knots and 25 knots.

The following diagram shows the problem in a general form, where:

Ao Angle before the beam of the enemy
De Distance traveled by the enemy unit over the time interval
Df  Distance traveled by your unit over the time interval
R   Range to the enemy unit
A   Angle to steer toward enemy

Although Chatfield says he can calculate ‘perfect gunnery courses’, the range is not precisely constant over the time interval. It is only the same at the start and end points. Line Df would need to be a curve (implying a continuous change of course) to keep the range constant at all times.

A general solution to the problem can be developed by using the Law of Cosines. The area swept by the fire range is divided into two triangles:

To keep the formulas to a manageable size, intermediate terms are calculated:

Tables for various combinations of speeds, ranges and angles can be created:

Seekrieg 5 – Gulf of Finland 1916

December 9, 2017

This weekend the local HMGS-South group played a WWI naval game using the Seekrieg 5 rules.

May 15 1916,  07:30 Western Gulf of Finland
The Russians launch a heavy raid against the German patrols/ blockade of St Petersburg. The Russians sail from St Petersburg just before dusk on the 14th. At dawn both sides are sighted. Clear good weather. Visability starts ar 18,000 yards, increases to 24,000 yards by turn 5 as the morning haze lifts.

Russian:
BB Petropavlovsk
BB Gangut
CA Bayan (II)
CA Rurik
CL Jemtchug
Speed 14 knots. Course 270.

Germans:
BB Helgoland
PBB Deutschland
PBB Schlesien
PBB Hannover
CL Berlin
CA Roon
Speed 8 knots. Course 090. Initial direction to the Russians determined randomly.

Victory is based mostly on damage inflected. The Russians need to avoid a lot of damage. They cannot replace their ships, and badly damaged ships will find no safe harbor for repair. The Russians would like to “run” the Blockade to get into the German merchant shipping, but have to be only lightly damaged for that.

Mines: The Gulf of Finland has been mined by the Russians, but the Germans have prevented the Russians from maintaining the minefields. Some mines have broken loose and wandered. The mines have a low chance of contact (<5% / column of ships / turn). Slower ships can better avoid them. Only the lead ship of a column is at risk. The Russians have out of date maps, giving them some knowledge of where the mines are. Mines should influence tactics but not dominate the game. If ships stay in column there is about a 48% chance of one mine explosion in an 8 turn game.

 

Both sides led with light cruiser to take any mine hits. None occurred. Both sides turned to the north to bring their batteries to bear. With the rear ships out of range, the early turns pitted the two Russian dreadnoughts against the dreadnought Helgoland, while the armored cruiser Roon targeted the light cruiser Jemtchug. After 8 turns the Helgoland was a wreck (8 tiers of damage, two fires and only one remaining damage control team). No other ships had been significantly damaged. We called the game as a Russian victory.

 

1/6000 Naval – Various Late WW1 or Never

November 24, 2017

Filling in some of the gaps in the 1/6000 naval fleets.

[EDIT] Added some Austro-Hungarian protected cruisers and Russian seaplane carriers.

Seekrieg 5 – Dreadnought 1906

July 8, 2017

This weekend the local HMGS-South group played a WWI naval game using the Seekrieg 5 rules. The year is 1906. The British have just completed a new battleship. Navel experts claim it makes every other battleship obsolete. HMS Dreadnought and two British pre-dreadnoughts take on six German pre-dreadnoughts.

After about 4 hours of play and 20 game turns (40 minutes) we called the game. Damage results:

Pommern, 3 tiers, 12 knots
Schlesien, no damage
Braunschweig, 1 tier, boiler damage repaired
Schleswig-Holstein, light damage
Deutschland, 4 tiers, 15 knots
Hannover, 1 tier, 6 knots

Dreadnought, 4 tiers, 17 knots, both wing turrets out
Hindustan, light damage
Prince of Wales, light damage

 

Bay of Algiers, 1914, Again

April 15, 2017

This weekend the local HMGS-South group played a WWI naval game using a modified version of a scenario tested previously.

This fleet action is based on the Triple Alliance naval convention of 1913, as described in “The Great War at Sea” by Sondhaus. The plan was for the Italian and Austro-Hungarian fleets and any German ships in the Mediterranean to engage the French Fleet and block the Algerian troop transports. This scenario assumes that the war starts in February 1914, and that the British Mediterranean squadron joins the French.

The confrontation occurs north of the Bay of Algiers.

Visibility 18,000 yards. Wind NNW at 3 knots. Seastate 1

Status at the end of the game: alg2 io

Damage output file: alg2-output

Plot of ship movements:
0 to 20 minutes alg plot 0-20
20 to 40 minutes alg plot 20-40
40 to 55 minutes alg plot 40-55
55 to 70 minutes alg plot 55-70
full plot alg plot all

Computer code (described here)

The French had more undamaged ships when we quit, so the troop transports should be safe.

Seekrieg 5 – Newcastle Raid

March 25, 2017

This weekend the local HMGS-South group played a WWI naval game using the Seekrieg 5 rules. A German squadron has bombarded Newcastle and is returning home but is spotted by a British dirigible. While still 200 miles from Heligoland, it is intercepted by a British squadron to the SSW.

German Squadron:
Armored cruisers Roon, Yorck, Prinz Adalbert
Light cruiser Pillau

British Squadron:
Armored cruisers Defence, Shannon
Light cruisers Arethusa, Aurora

We quit after 11 turns due to the time. On the British side, Defence and Shannon were lightly damaged with no critical hits, Arethusa was gone and Aurora was down to 16 knots with boiler and engine damage. On the German side, Roon had more than 40% damage and had lost a main turret, Yorck was gone, Prinz Adalbert had light damage and Pillau had medium damage.

 

WW1 Naval – Churchill’s Idea

January 28, 2017

This weekend the local HMGS-South group played a World War One naval game based on this March 9th 1915 memo (item 121 Jellicoe Papers) from the 1st Lord of the Admiralty. The idea was to send a fast division into the Baltic Sea and, in cooperation with the Russian fleet, blockade German ports. The Germans send the ships that were in the Baltic for training exercises.

The confrontation occurs off Aarhus, Denmark: aarhus-10nm-grid

Status at the end of the game: io

Damage output file: chur-output

Plot of ship movements:
First 25 minutes: chur-plot-1-25
Last 25 minutes: chur-plot-25-50
Entire plot: chur-plot

Computer code (described here)

Seekrieg 5 – North Sea Encounter

November 26, 2016

This weekend the local HMGS-South group played a WWI naval game using the Seekrieg 5 rules. Initially the game was set up with a four ship division on each side, but we scaled it down to two ships on each side due to the low holiday weekend turnout.

The forces started 20,000 yards apart in good visibility. The British had two Iron Duke class battleships and the Germans had the Baden and a Konig class. The players rolled for crew quality and all ended up the same. The game ended when the lead British ship was destroyed by a magazine explosion.

Coronel and the Falklands

October 19, 2016

The book “Fatal Choices, Wargames, Decisions and Destiny in the 1914 Battles of Coronel and Falklands” by Seth Owen includes historical and non-historical wargame scenarios associated with the cruise of the German East Asia Squadron. Several of these were played as solo exercises using this computer code. The code is not intended for small scale actions. The main drawback in using it is that orders can only be changed every 5 minutes. Using the options for automatic target selection and opening fire mitigates this to some extent.

The Battle of Cocos

The fight between the Sydney and the Emden. The damage the Sydney sustained seems to be more than in the actual battle.

Status at the end of the game: cocos-io-10-10

Damage output file: cocos-output

Plot of ship movements: cocos-plot-10-10

The Battle of Samoa

A hypothetical battle between an Australian squadron including the battlecruiser Australia and von Spee’s squadron. The Australia takes significant damage. The Gneisenau runs out of 21 cm shells (her primary battery), in part because while the Australia was firing at Scharnhorst, Gneisenau could keep up a higher rate of fire. According to the NAVWEAPS site, the Scharnhorst class had 87.5 rounds per 21 cm gun.

Status at the end of the game: samoa-io

Damage output file: samoa-output

Plot of ship movements: samoa-plot

The Battle of Coronel

The historical battle between Cradock’s squadron and von Spee’s squadron. The Scharnhorst runs out of 21 cm shells and the Gneisenau nearly runs out. This may be because the range was generally longer than in the actual battle, or because the penalties on rate of fire for poor visibility are not severe enough.

Status at the end of the game: coronel-io

Damage output file: coronel-results

Plot of ship movements: coronel-plot

The Battle with Canopus

The fight between the pre-dreadnought battleship Canopus and the armored cruisers Scharnhorst and Gneisenau. Both armored cruisers ran out of 21 cm shells and the Canopus was finished off with the 15 cm secondary batteries. Torpedoes may have been a better choice. If this encounter had occurred historically, low ammunition after the Coronel battle would probably have caused von Spee to avoid Canopus.

Status at the end of the game: canopus-io

Damage output file: canopus-output

Plot of ship movements: canopus-plot

The Battle of Coronel including HMS Defence

A battle between Cradock’s squadron, reinforced by the armored cruiser Defence, and von Spee’s squadron. This is a lot closer fight than the actual battle. With Scharnhorst sunk and Gneisenau out of 21 cm shells, von Spee’s squadron would probably break up into individual raiders.

Status at the end of the game: defence-io

Damage output file: defence-output

Plot of ship movements: defence-plot

The Battle of the Falklands

The historical battle between Sturdee’s battlecruisers and von Spee’s armored cruisers. The battlecruisers took more damage than in the actual battle, possibly because von Spee’s armored cruisers did not try to run.

Status at the end of the game: falklands-io

Damage output file: falklands-output

Plot of ship movements: falklands-plot

The Battle of Stanley

A hypothetical battle between Sturdee’s  squadron and von Spee’s squadron, assuming that von Spee attacks before Sturdee is underway. The scenario in the book started with the Gneisenau and the Nurnberg approaching Stanley and the rest of von Spee’s squadron 15 nautical miles away. To give von Spee more of a chance, this exercise assumes that he approached with his squadron together. Timings for Sturdee’s ships getting underway are from Corbett, not from Owen’s book.

Status at the end of the game: stanley-io

Damage output file: stanley-output

Plot of ship movements: stanley-plot (the outlines of Stanley harbor and Port William are not shown on the plot, but were used for the game)

Initial positions showing coastlines: stanley-coastlines

Updated plot with shorelines: stanley-plot-shorelines

 

 

Seekrieg 5 – Falklands 1914

July 9, 2016

This weekend the local HMGS-South group played a WWI naval game using the Seekrieg 5 rules. The scenario was based loosely on the situation in the Falklands in December 1914, but with significant historical revisions to produce a more balanced battle.

The scenario deviates from history just before von Spee’s squadron reaches the Falklands. Von Spee is alerted to the presence of a strong British force, hides until dawn on 9 December and then uses the cover of fog to start for the Argentine coast. The British divide their forces to search, and one element finds the Germans. The scenario was scaled to give one ship to each of the five players.

Visibility 12,000 yards.

British: battlecruiser Invincible, light cruiser Bristol

German: armored cruisers Scharnhorst and Gneisenau, light cruiser Dresden.

The German ships (especially Scharnhorst) were given an advantage in crew quality to help the scenario balance.

After about 4.5 hours of play, we stopped play. Damage was about even, mostly to Scharnhorst and Invincible. No ship had been sunk or crippled.