And if you need specific info on individual ships (not necessarily sunk or damaged).......I use the British National Archives Merchant Ship Cards
The cards record the movements of both British-registered and Allied vessels engaged in the war effort.
They DO NOT give you passenger lists or details on who was on the ship
Here's an example of what the card looks like
This is a FEE service, but I find the cost very reasonable, about $9.00 Cdn for each record. And the records are delivered On-line (you can download the record as soon as you have paid for it)