Deeply dippy

■ I recently replaced the depth meter in my Dehler 31 with a Raymarine i40 bidata depth/ speed meter. Both through-hull transducers were inserted and the display was connected, but while the speed showed correctly on the display, the depth meter gave up after a while. The shop staff were very helpful: both the display and the through-hull transducer were replaced (the through-hull transducer by an in-hull version). However, after a while the depth meter gave up again. I found this very surprising as I’d previously used a Navman/AdvanSea combination, which worked fine for more than eight years.

The other week, I investigated a little further. When I removed the in-hull transducer from its oil bath, the depth measurement was still showing 0.6m, as it was before removing it. After putting some new oil in the bath, the meter showed the correct reading: apparently there was a tiny amount of oil leaking, which explains why it was functioning for a while and stopped working afterwards. So, I now know the cause of the issue. The solution will be to remove the oil bath, clean it and refit it – this time with epoxy instead of Sikaflex to prevent leaking.

Lessons learned? Firstly, a constant reading on the depth meter apparently means it is working, but not correctly (probably caused by an air bubble in this case). And secondly, the in-hull transducer is very susceptible to air bubbles.