Torpedo effectiveness

[Obersteuermann]

Last night I sneaked into a nice large convoy just west of Ireland. I sneaked past all the escorts, got right amongst the columns and started firing my eels.

Out of 7 fired (all bow tubes plus an extra couple, and the stern tube) I scored five hits - but only one ship sunk. Each of my targets were 8k-10k tons and received two torpedoes: one fused for impact and running at about 1.5m - 2m depth and one magnetic eel set to run about a metre under the ship's keel.

I didn't hang around near the surface to see what hit what (learned that lesson the hard way!) but I did immobilise a Liberty ship. When the escorts had safely passed by I surfaced and had a good look - seemed that the surface runner had holed his engine room just below the waterline.

Later on, while running back to Bergen, I came across a lone tramp steamer and put a magnetic torpedo under his keel. It was a perfect shot, straight under his funnel, but it had no effect at all. If anything, it sped him up!

What am I doing wrong with the magnetic torpedoes? They don't seem to be inflicting any real damage...