[TorpX]

There have been comments recently to the effect that ISP, and other physics mods are harmful to convoy integrity. I decided to test this notion, and see if there is anything to be learned.



First, I created a mission for the purpose. I put together a 12 ship merchant convoy. The convoy 'leader' is a large minelayer (not actually a merchant), the other 11 are an assortment. No real small or large ships. The biggest is a large old liner. I put a lot of 'old' ships in it, the idea being these might have more trouble keeping up. All the merchants have novice crews, all the DD's normal crews.

Additionally, there are 4 escorts, one ahead, one on either beam, and one astern. The rear escort is a small minesweeper, all the others are DD's.

The arrangement is 3 columns of 4 ships. There is about 500 yds. in between ships in a column, and about 1,000 yds. between columns. The escorts were placed about 3,000 yds. outside the convoy, but wonder around a lot, so I'm not sure it matters where we place them.

I had them follow a large rectangle, but instead of having them make 90° turns at the corners, I used two 45° turns spaced about 5 nm apart. I have doubts as to their ability to make sharp, or frequent turns. The weather is a little choppy, with 6 m/s wind. The mission starts at 0800.



Test #1

The date is Nov. 7, 1941, so the USN and IJN are still on speaking terms. I am using RFB and RSRDC with the required patches. I believe that these mods use 'stock' physics, and you would get the same results in stock, but I wanted to make sure the ships were the same.

The convoy starts out in good order and apart from one of the DD's almost smacking into me, not much happens. I do notice the Wakatake and Matsuki DD's look somewhat unstable, rolling more than they should. Could be a problem in heavy weather.

I use 32x TC for most of the time, going to 1x to examine the ships from time to time. In the turns, I notice they use an odd technique. One ship, the medium old comp. fr. looses it's place twice, not clear why. It then tags along, at the rear of the column, until eventually finding it's way back to it's proper place.

In spite of these minor issues, the convoy ships keep station pretty well. I can't follow them after dark very well, but when I spot them again, they look to be in good formation. My boat actually collides with one in TC, and makes a lot of nasty racket. I threw engines in reverse and the merchant gets back to the convoy. We have no damage and apparently they don't either.



Test #2

Same set up as above. In this one I pull ahead out of sight, submerge and ambush convoy with a salvo of 4 torpedoes. This with auto-targeting. Range was about 8,000 yds. and I used 1/2° offset angle. I aim at two ships in the far column, from long range (i.e. low speed). One of the first two hit, the others miss. The convoy looks disordered for a while, but goes on, intact. The one ship sinks.

After a short time, I fire another volley of 4, at two other ships. Two ships are hit (1 hit apiece), but not the ones I targeted. One sinks quickly, the other struggles on for 30 min. or so, before it too, sinks. The convoy stayed together.

The oddest part was how little the DD's attempted to interfere. One DD (at front) worked it's way back through the convoy, as if it was trying to locate a sub inside the convoy. However, there were no ship collisions. I couldn't follow the evasions of the individual ships, but it was obvious they detected the torps and attempted to evade.



Tomorrow, I'll repeat the tests with ISP.