You have to remember that in RFB, the Damage Model for ships is being changed from a "Hit Points" type system to a "Flooding" type system. Also the civilian (Merchant) ships damage models have been reworked on by Luke & Observer, and the warships have not been done yet.
Luke is still working on the Destroyers, then on to the larger warships.
You can get ships to sink with 1 torpedo, but you have to be very lucky and hit the right spot. In most cases you are going to need to use multiple torpedoes on the merchant ships to get them to sink.
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Jim
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