The Schnellboote often used depth charges against allied submarines, these were merely set for a depth and then rolled off the stern of the boat using a set of rails that overhang the stern. The depth charge would sink down to the set depth where they would explode and because of the high density of water would cause a shockwave that would disable or even destroy the target.
I tried a laser cut infill assembly for 25mm OD carbon fibre tube, looks pretty good. I also have a 20th scale 3D printed Depth Charge coming.
The Depth Charge Rack completed.
Three depth charges strapped to the launching rack with some scale chain.
I found this photo of the original WW2 depth chargers.