[TG11] ST40 Depth flashing "Last" in 15 ft of water

[Tom - Raymarine - Moderator]

Hello B-A,

I'll go through the problems one by one.

Depth data: the display will show the last depth when it's unable to detect a decent signal strength from the bottom. The fact that this is most common after a tack etc. is evidence of this: the disturbances in the water across the transducer in the turn have the effect of dropping the signal level further.
If the echo from the real bottom is weak then occasionally a depth transducer can pick up a signal from the keel with the outer fringe of the beam (particularly common with bulb keels); the display will always report the shallowest strong return as the depth. I suspect that this is why you're seeing a consistent shallow depth number.
As to why this problem has occurred now: my guess is that the transducer element has been damaged, e.g. by a strap resting on it or by hull cleaning done during the lift.
Another alternative is that something in your boat is now giving interference at around the transducer's 200kHz frequency; this could me almost any electronics, even if not new or not apparently faulty.
A good technical dealer can test the transducer with an Airmar transducer test set, test the display with a sounder test set, test for interference with an oscilloscope or test any of the above by isolation and substitution.

S100 range: this could be that either the S100 or base station is failing, or that you have an RF interference problem. A good technical dealer or one of our service centres would be able to test it for you.

ST60 Wind angle alignment: the Linearisation process is only required at first power-up or if changing the masthead sensor or display. It will only occur on first power-up (out of the box), or after a Factory Reset. It's not required to adjust the alignment, though: you can do that in User Calibration without doing circles.

Regards,
Tom