Currently the DE impalers on ships read as if they do 6 troop damage.
Upon testing them I noticed that they do not. Here a battleship launched 3 impalers and did 9 troop damage while a light cruiser launched 1 impaler and did 3 troop damage.
Upon launching the impalers, the impaler from the DE cruiser and light cruiser launch in a damaged state.
Also unsure if this is a bug or was intentional, but the light cruiser and cruiser both only launch 1. Most likely it is supposed to launch 1 instead of 2.