I have a ST 50 plus tridata. Recently the boat speed reads about half of what the SOG (from GPS) reads. I have checked at slack tide and same problem. I just replaced the speed/temp transducer with a ST800 and same problem. I went through the ST 50 plus re-calibration (not as easy as you might think) numerous times and the cal factor was 2.5 which is higher than the allowable limit so it didn't store the cal factor or fix the issue. I am having basically the same issue with the new transducer as with the old one. I also have a Ray-marine C7 MFDU and i60 Wind right now everything is tied togeher so I am worried that swapping out for a newer i50 tridata will cost a lot and not fix the problem.
Thanks,
Thanks,