Mariner depth sounder
Bryan, I have a mariner depth sounder that plagued me for years. It was sent back to the factory, checked and returned as working...and it did for a while. It was unreliable in that it would stick at different depths, but particulaly in the 10 foot range. I ahve an old friend who worked instruments as far back as WW2, we removed the unit and he looked at it over the winter. The electical unit fits into the case like a piston into a cylinder and he found that the unit went too far forward so that the indicator(needle) actually touched the front of the case, causing it to stick. His solution was to add a thin aluminum spacer to give more clearance between the needle and the front of the case. Also, check carefully to see if there is any side pressure (too small a hole) that could cause the case to distort (even a little). This solution presumes the unit and sender does work electically, but I would think that the needle would indicate "0" if it wasn't sticking. Hope this helps, those false readings drove me to sailing with the unit turned off.
