Hi JU_88,
tnx 4 your answer.
I probably didn't speak well my mind.
I agree that the sailing boats don't have/use engines, therefore any sound can't be detected by hydrophone!
BUT...
why did my sonarman detect them?
He reported to me, while submerged, ship type (merchant), speed (8knts) and bearing.
I can't explain this last thing. :hmm::hmm::hmm:
BRGD
mau----