I love my deck gun. I use it to terrorize lone small merchants. I even manage to use it on a type IXb in 1945 about 50km north of the Scotish Coast. Fishing vessels that are messing up my sonor readings are prime target. but once in a while I will also attack Passenger Cargo and medium cargo (two ships that I have yet find a trusted way to sink with one shot.) Even costal merchants when I am low on torpedo.
Armed merchants in GWX are tough customers, but I have devised 2 ways to kill them with little or no damage to my boat.
1. Close attack: Mainly against coastal merchants and small merchants, they usually have 1 deck gun (or less), either for or aft. Let's say it's aft. I will surface 500-800 meter dead ahead of the ship and start pumping rounds into her. (I have a very specialised deck gun crew, hance reloading is much faster). Move backward to maintain distance as soon as I surface) The victim will have to turn their ship to fire their guns. You MUST take those guns out ASAP. With the first few shots you shall know how to hit their gun as before they come into view.
If you loss your nerve and try to submerge, you will take more shots than if you stay in the fight.
Advantage: few wasted ammo, quick resolution
Disadvantage: you must do a full list of thing very quickly upon surface. (you should preload your first shot long before the engagement) Once they start firing, you WILL get hit.
2. Range attack: (against wounded ships, or medium ships that are armed fore and aft)
Range 3000-5000 depending on visibility. I usually do this at night. I will follow the victim at range at either their 5 or 7 oclock (bigger profile to hit).
I will surface slowly. They won't sight me immediately, I can usually get of 5-7 shots and submerge again before their return fire start. Wait until they turn off their serch lights, surface, and do it again.
Adavantage: I am rarely hit in return.
Disadvantage: takes a lot time, a near by destroyer might show up or your intented victim reach more protected area. more wasted ammo.
Eitherway, the wind speed must be 4 knot or less, otherwise you are just wasting ammo and risking life for nothing. And you must man the deck gun yourself. AI-control deck gun is a joke.
On a good patrol, I will add 5000-15000 tonnage with the deck gun. I once deck gun HMS Aquitania off the South African Coast. That was quite memorable.
