Ship Speed and Convoys (Boat Racing)

[paul_leonard]

I recently developed an interest in creating missions involving convoys, specifically coastal convoys, specifically those in 1940. So I've been building ship convoys and learning what works and well... what works in unexpected ways.

Coastal shipping had always brought the necessary coal from the north and west to London to fuel energy production, heating and manufacturing. The British rail system never had the capacity to move enough coal around the country to supply these needs. So disrupting Britain's energy delivery system was strategic in nature. The need for convoy protection was a function of offensive/defensive mining, offensive naval activity and air threats. Convoys are inherently inefficient as they overload/imbalance stevedoring and dock facilities.

One of the first things I found was that simply setting the speed of ships in a convoy, each at the same speed, resulted in some ships catching up with other ships and colliding into the other as I had ran the ships in single lines, albeit separate by around 500m. So speed seems to be a relative thing in the game, not absolute (kind of like the speed of sound I suppose). So I started a boat racing mission where I pitted all ships against one another, at the same speed, and watched as they covered different distances in the same amount of time (d/t <> v). I then adjusted the "speed" of each ship to get them to cover basically the same distance in the same amount of time, give or take a ship length. The results are in the CLoD Ship Performance spreadsheet in the attached zip file. I ran this for a convoy running at a historical 10 knot average speed. See the results in that mission file and spreadsheet. I then learned that if I wanted to include small coastal freighters their maximum in-game achievable speed would not allow them to keep up with that convoy speed. So I also created a convoy set at 6 knots (12 km/h) so that I could include the Small Coastal Freighter, as I believe this was historically a participant. You will note that the some ships will require to be set at higher speeds to keep with the convoy. That is in the spreadsheet. Finally I did the same with a warship fleet at 20 knots (40 km/h) as there ae scenarios that would be warship only. Obviously as you will see from the spreadsheet, it is a limited number of ships that can maintain this higher speed in formation. I've also included the mission files in the zip for each of these tests.

When running the missions there is no aircraft or player. So when you start the mission you will be asked for a Player Plane. Forget that. Hit the Back button and then choose the Fly button. The mission should start and you will be following a ship. You can jump between ships and change views using the in-game camera/view controls as you have programmed them.

So then I built convoy Forth-South 216, short form FS.216. It set sail southward from the Firth of Forth on the evening of July 7, 1940 and arrived 725km (400 nautical miles) later off Southend (London) the afternoon of July 9, 1940. One day before the "official" start of the Battle of Britain. That afternoon it was attacked by approximately 70 Do-17s, He-111s, Me-110s and Me-109s and defended by about 20 RAF Spitfires and Hurricanes of the RAF. Shhhh, don't tell the combatants of that day that this wasn't THE BATTLE OF BRITAIN. Also, Flight Lieutenant Ironside who was shot down, survived but was blinded and never flew again is not one of THE FEW. It's also attached as a mission file. It's not perfect, some of the ships still behave erratically in that their speeds, while programmed using the race results, vary somewhat, even amongst the same ship type. So you will notice that I've adjusted the paths of the ships so that some can pass each other without hitting one another.

I could go in and individually adjust the mission files using Notepad (better yet, Notepad++) and adjust their speeds to perfectly stay in formation. Here is how you would do that.

Open the "mis" file and you will see for each ship that it has a path (Road) for each ship (Chief) defined as follows (the ship system names are in the CLoD Ship Performance spreadsheet):
[0_Chief_Road]
244925.05 278960.13 38.40 0 2 3.89
218290.08 273855.22 38.40

[This is the Road (path) for Chief (Ship) 0 where Ship/Chief 0 is set further above in the mission file.]
The first two sets of large numbers in each line above are the beginning and ending two waypoint coordinates on the map. Think in-game latitude and longitude.
The 38.40 I have no idea, maybe the depth of the ocean?
The zero and the 2 I have not figured out yet either but I suspect have something to do with the type of MOVE action they are taking.
the 3.89 is the speed you set (in km/h) in the FMB divided by 3.60. WTF 3.60? I have no idea why, but 3.89 x 3.60 equals 14 km/h. Go figure.
So if you want to precisely set the speed of a ship you can do it in the mis file, something you can't do in the FMB which uses only whole numbers for speed. I will leave it up to you dear reader to conduct your own experiments.
The second line is blank for speed and movement (?) but the ships will come to a stop at the end waypoint. If you look at the FMB the final waypoint speed will override whatever you put in and read something like 4kmh but near as I can tell they will actually come to a stop. I've watched this happen a bunch of times.

This is kind of how I know the maximum speeds. If you put in a very high speed, like 90kmh in the initial waypoint speed setting, it will ignore that and replace it with the maximum speed the game will allow the ship to move at. Tip: this functionality will also work with aircraft if you are setting aircraft waypoints. Sidenote: This is also a flaw with the Quick Mission or Single Mission builders (at time of writing) as any player who changes the aircraft from the default aircraft may end up with a disconnect between the waypoint demanded speed of the mission and the capabilities of the changed aircraft. This is a real problem when switching from a default monoplane to a biplane for example in Tobruk based missions.

Here are some other things I do when I built this FS216 mission.

Regardless of what ship you choose to place, you have to make them all Red Army (in this case of British ships). Do not confuse Army=None with neutral. Army=None means that they treat everyone else as an enemy, not as a friend. They will begin shooting at anything that is Army=Red or Army=Blue. I mean anything. If you think about it though, there are some scenarios, be they ships, or otherwise, where you may want that to happen.

Speaking of shooting, the gunners on ships, unlike the historical gunners, are brutally efficient and brutally accurate. (Historic sidenote. Gunners were trained to join a ship in a convoy, man their weapon, and then either join another ship heading back or take a train back to their starting point. The train option was very common on CW Convoy West convoys that started in Southend and stopped in either Portsmouth or Portland before going further west). So, I always make their Skill=Rookie (generally inaccurate but very intimidating nonetheless) and I increase SlowFire=1 to SlowFire=5. SlowFire is a weird setting. It affects the gunners reloading time, in this case lengthening it by 5 times. This effectively slows down the reload time, reducing the rounds per minute rate. Again, go figure. Adjust as you see fit, but that is what I do. These settings are important once you add other combatant planes or ships.

UNDOCUMENTED FEATURE (A bug at time of writing)
If you receive the error message "Error Loading Mission Object Reference not set to an instance of an object" you most likely have the SpawnHumans=1 setting in your conf.ini file. This setting will show soldiers associated with certain objects. This is a very cool undocumented feature. This is normally set at SpawnHumans=0 as I believe it is unstable to turn on. Well I know it is. Some objects have been programmed in but don't have humans properly associated with them. I know for a fact at time of writing the the Landing Craft Assault breaks when SpawnHumans=1 is set. Breaking will break the mission. There may be other objects and ships that also generate this error. So show humans at your own risk.

Last but certainly not least, the attached zip file has a spreadsheet database of nearly 8,000 ships that sailed with convoys through the Channel between June 29, 1940 and November 2, 1940. This database has been constructed using the invaluable Arnold Hague Convoyweb at http://www.convoyweb.org.uk/ and with reference to Nick Hewitt's "Coastal Convoys 1939-1945: The Indestructible Highway" book. Using tonnage information I have been able to match the relevant in-game ship type within the spreadsheet, enabling me to construct the composition of a historical convoy that can be created in-game.

ATAG_Lenny

CLoD Ship Study.zip