BobB, with the 360 TM on my 998c SI you are correct, it can only be set backwards. But when I read the manual all the "off set" is for is to correct the GPS receiver location error so it is easier to determined were the waypoint is actually at. If your GPS is at the rear of your boat and you mark a waypoint that is under the TM xducer, the waypoint is set where the GPS receiver is located, which could be 20' to the rear on a big bass boat. Is this not correct? On my boat the GPS is only 3' from the TM. dj