Strange convoy encounter

[scubamatt]

OK, so I started a fresh campaign today, upping the difficulty from the last one. Started in Manila 8 December, with a Sargo, USS Sealion.

First mission is to drop off supplies in Formosa, no problem. Spent some time sorting out my crew, started a patrol log in my word processing program so I can write it up as a story when I'm done, then set out for Formosa.

Dropped off the stuff, called in for my next mission, got 'Patrol five days in Convoy College area' covering north half of Luzon. Motored back down that way, and just after dawn on 12 Dec my lookouts spot a Task Force moving NNW directly towards me...at *slow* speed. I've never seen a slow speed TF before, they're always going like a bat out of hell, so I get into position and (very) carefully scope them.

7x Small marus (name starts with a T, like 1200 tons each)
8x DD escorts (name starts with an A, about 2500 tons each)
2x Kuma class Light Cruisers (5100 tons each)

My loadout is half Mk14s half Mk10s (my torpedo officer isn't comfortable with the new dual speed torps, so we compromised). I have a long range, bow on shot at the lead cruiser, who appears to be the only ship *not* zigzagging, and he's moving slow.

I send two 14s his way, 2 degree separation on them in case he tries to turn to starboard. Dive deep, clear datum before the escorts even know I'm around. One explosion happens sooner than I expected, so I assume its a premature detonation. The other runs along for a couple of minutes and then hits the Kuma...sinking it! The event camera shows the Kuma was *already down by the bow* when I hit it with the fish! It was already heavily damaged by someone else, I guess.

I motor away from their line of travel, and get some more distance from them as the escorts scurry around looking for me. I come back up to periscope depth for a peek, prepare all of my torps fore and aft for some serious speed shooting.

The convoy is much closer to me now, and I can see that nearly all of the marus have burning smoke plumes! The whole convoy is made up of damaged/burning merchants, and the second Kuma is listing to starboard, just limping along! The escorts are fine, no damage and zipping around like mad hornets. I have never seen a 'pre damaged' convoy before.

I unload all four tubes in the general direction of the Kuma, execute a flank turn to bring my aft tubes to bear, one of the escorts spots me or my fish and starts pinging and coming to me. I empty all of the aft tubes at him and the ships beyond him, then crash dive.

Most of my fish miss, but I hit two marus, and the other Kuma. None of them sink apparently because I get no kills in my log , even though the event camera shows three ships capsize/sink. I endure some DCs and then the escorts give up. I motor along while the crew reloads the tubes. Watching the sonar reports, I figure I'm SE of the convoy now, since its been a while. I decide to go up for another peek and maybe some shots into a cripple. About the time I get to periscope depth my sonar guys are reporting warships SE of *me*, merchants and warships NW of me, and warships NE of me. Nonstop contact calls, I thought they lost their mind.

I put up the scope, do a 360 look and I am between TWO convoys, the original limping along to the NW still lots of burning damage visible, a little gaggle of escorts circling my last position to my NE, and _another_ full convoy of escorts and cruisers to my SE (Heavy and light cruisers with a lot of escorts, all moving fast along the coast).

I counted ships, paused game, counted more ships, and tried to take a screen shot (apparently I did not do it right because it took a SS of my desktop, but not the in game view).

In total, with two convoys and escorts there were more than 30 enemy ships within 9.6 nm of my sub. I felt like a mugger standing in the middle of the Interstate highway, trying to figure out which way to point my popgun. I ended up trying to finish off some of the slower and already wounded convoy, as the warship TF was really hustling. Eventually, I nailed four marus and the one Kuma, and escaped with minor damage, despite FOUR duds/swim unders.

Never seen a predamaged convoy before, and never seen two TF in the same area at one time, it was very very odd.

[Sniper297]

Those "task force" fiascos are in the EastAsiaCampaign.mis file in the campaigns. I've never been able to fix them or figure out what exactly is wrong with them, but for some reason they get lost between waypoints, start creeping along at 1 knot, then suddenly speed up to run circles around each other like a bunch of waterbugs. Best policy is when you see the tiny troopships, just avoid the whole mess and go somewhere else. They're mostly concentrated on the west coast of Luzon. The reason for premature damage and/or sinkings is because the drunken lubbers collide with each other when the formation goes spastic. The small troop ships are around 1800 tons, the light cruisers are barely worth a torpedo, and the ones with heavy cruisers are usually MOGAMI class which are barely worth two fish, so you're not really missing much by avoiding them.

[scubamatt]

Aha that explains things, then. I was off the west coast of Luzon when I ran into them. I admit, since I didn't see any flaming smoke the first time (they were almost out of visual range) I thought maybe I had loaded one of Robbin's 'slightly sub nuclear' deck gun shells in a torpedo by accident. I wish I could figure out how to take a screen shot in game, it was a pretty spectacular sight for me.

I thought it might be a bug, with the event cam showing some sinking, but no kills for me. Ramming each other makes sense, they were all in a gaggle pointing every which way and mostly stopped at one point.

I will go back to my previous save (after dropping off the supplies in Formosa) and plot a different course, to avoid the encounter.

I appreciate the info, too, thanks!

[TorpX]

Those "task force" fiascos are in the EastAsiaCampaign.mis file in the campaigns. I've never been able to fix them or figure out what exactly is wrong with them, but for some reason they get lost between waypoints, start creeping along at 1 knot, then suddenly speed up to run circles around each other like a bunch of waterbugs.

Do you think it is because they have to thread their way around small islands?

[Sniper297]

No, looking at them in the mission editor most don't thread their way through anything except a lot of convoluted waypoints - most likely problem is too many waypoints too close together with too many sharp turns? The one that goes into Lingayen Gulf for example makes a 90 degree starboard turn, runs on that course for about 5 miles, then makes another 90 degree starboard turn for a complete 180 degree course reversal. 20 miles later it makes a 135 degree turn, then a couple more turns, meanwhile the escorts breaking out of the screen to make random sweeps then trying to get back in position while the cruisers and troopships are trying to maintain (or recover) the formation during a turn have to alter course trying to avoid collisions with the escorts. I think what happens is eventually the program gives up trying to herd everyone back into formation and forgets where the next waypoint is. "Wandering all over the ocean like a drunken duck" fits these troopship convoys perfectly.

[TorpX]

I see.

Turns that sharp does seem to be overdoing it.

[Sniper297]

I've never seen any kind of manual or tutorial for the mission editor, just going by what I've found through trial and error. Units too close to each other or waypoints too close cause problems, so I would assume that too many waypoints and too many ships in a formation - especially a mix of types in an unusual pattern - would also cause problems. One thing I tried was replacing the 8 small passenger carriers with two to four large passenger liners, eliminate the lead cruiser so there's only two. No luck so far, follow the fleet long enough and eventually they start that milling around like waterbugs routine as if they can't find the next waypoint. I suspect the real cure is to redo all the waypoints so they're further apart and fewer of them, a less complicated navigation pattern.

[TorpX]

When I did some tests to check convoy behavior, I found they could do 90° turns ok, but I didn't try to force two close together. They do take some time to straighten themselves out after a sharp turn. I also had them well spaced, 1,000 yds. between columns. If they are jammed very close together, I would expect there to be problems, just like in RL.

Twisty-turny routes probably should be reserved for small convoys or single ships. I didn't really see problems related to a particular type of ship, or a mixture of them. However, any convoy is going to have the limitations of the slowest/least maneuverable unit.

I should also add that the convoys were not perfect, nor did I expect them to be. I only required they sail in a group and not fall apart. They did become somewhat disordered at times, either after a turn, or after an attack. Ships would get out of place, and sometimes 2 ships would end up jockeying for a spot. I don't see that as a serious problem. To my way of thinking, it would be worse if they sailed on in perfect formation, all the time.

[TorpX]

Actually, I think I didn't recall that correctly.

I think I put in two 45° turns instead of one 90° turn. Something like 5 or 8 nm apart. I didn't want to make it too stressful on them. So I can imagine if turns are greater than 90°, things can get sloppy.