Wilhelm,
Welcome to the forum.
When you lose contact is it in good visibility or poor,such as in heavy fog and rain?.A good way to re-aqquire the target would be to quickly make a sound check,by that I mean dive to about 30m or so facing roughly the direction the ship was lost and cut the engines.Have the sonar man make a sweep for a minute or two,and if nothing have a check yourself.If you hear him pulling away,quickly set engines on flank and give 2 blasts on the air for an emergency surface.Then head in the relative direction the sound bearing was took for no more than 15mins,and do another sound check,then repeat.If this is not a bug and he is not faster than you then you should pick him up in no more than 1 hour,usually in about 30 mins,depending on visibility of course
