There are two ways of looking at it.
1. it depleats the local enemy of a food source
2. its a waste of ammo
Personally, i dont attack civilian fishing vessels and yachts.
for starters submariners considered it bad luck to attack a boat that was rigged with a sail, and two... if they are able to radio in my position before i sink them the target wasnt worth the hassel of being located by an HK group or planes etc.
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