sinking ships

[GavNormandale]

yesterday while playing SH4 i encountered an escorted freighter, i flanked ahead and waited till they came back into view. after a while all that came was the escorting destroyer which i sank, still a little puzzled as to where the freighter had gone i went to the navigation map to see the red sunken ship icon near to where i first spotted it.

i had thought that all the other friendly ships were just for show, are they actively hunting?

also later i spotted another ship on radar, i tracked it and took a position ahead of it, i lost sight of it but positioned my self where i expected to meet it, this one never turned up and checking the map again i find a sunken ship on the path, this time in grey colour, was this a friendly ship sunk by the japs?

if this is true i didnt realise so much was going on in the game, i thought all the other reports were just made up

cheers

Gav