With RSRD you'll see many large convoys coming through Formosa and the Palawan passage in 44. Most have Type AB's as escort, they catch you dived in shallows, you're dead.
If you have a 40 bofor and a deckgun, get in the convoy and have at it. You don't need visuals, just estimate range and shoot down the bearing.
Try to get about 500 yards from the ship your attacking. I've taken out entire convoys like this with the DG and two 40's.
I usually come in from the rear between the escorts and go up the center between the two columns. Do you have APR installed so you can see if any ships have radar? The radar ship will guide the escorts to you so keep watching radar and why shooting hit the nearest warship tab. Keep a heavy trim in case you have to dive. Good thing is rough water, so even shallow it's hard for them to find you. If a escort comes, I'll dive and blow tanks when he passes and head to a merchant.
Usually once you hit a ship the entire convoy will go into alert mode and cut on the blinking lights giving you a good aiming point. Be careful, merchants may start to mill in circles, you don't want one to catch you with visuals. They may also cut on spotlights if dark enough.
I will often weave between the merchants, using them to block escorts.
I sometimes will use the torps using the blinker lights to aim by, just shoot within 600 yards or so by radar, hard to miss.
Oh, some ships may be loaded with ammo or fuel, don't be too close when they blow up or you'll be toast.
Many more large convoys in 44, historically the JP's started using a larger convoy system then.
They come through Formosa a lot. Sometimes you may have 2-3 large convoys on radar at the same time if you're timing is lucky. Sit outside Brunei Bay in 44, October to November is good. Where many TF arrrive and leave and most come back for the battle of Phillipines. Both the Center Force and Southern force leave Singy and head there, dock and then to the battle, but come back after, several other TF come and go then.
Here's some storm SS surface battle shots using all guns, took out 13 merchants in this convoy
