Ladder torps, brilliant!
These torps are aimed and fired exactly the same as all the others. However when they reach the end of their intial run (this distance you can specify, usually just beyond the target you are shooting at) the torp turns 90deg to port or starbord.
Once again you can specify the direction of turn. The torp will now hopefully be travelling in the same direction as your contact. It will then turn again as shown in the diagram and continue as shown till it runs out of steam/batteries. Both the distance between rungs and length of rungs can be set up by you the user.
The obvious advantage of this torp is that if you miss on the initial solution, it may just turn round and get the target anyway. With this in mind you can take your shots from a greater distance, but remember to allow the torp to have some juice left to make the ladder search.
Good Luck