Like Korpdorfer and I had asked in February 2 :
Kopfdorfer is correct, put a 12 pounder/75mm or a 88mm gun on the bow plus a couple of 20mm, amidships and/or stern, the bigger one could play a very good HMS Naval Trawler or a VP Boot ( the German armed Trawler ) for Coastal/Harbour/Fishing Fleets protection, and a huge lot of attack missions on the Channel/Baltic/Mediterranean/Pacific theaters.
So, the armed trawler was the most encountered armed ship on the coasts of Norway, British Isles, North Europe and Mediterranean, they escorted almost all convoys on these areas with a few, generally no more than one, escort destroyers, frigates and/or minesweepers.