Data Marine Depthsounder readings

The reading on my Data Marine depth sounder jumps around. It will say 150 feet then 37 feet then 147 feet then 41 feet. The boat is new to me and it has done this since I bought it. The boat had been hauled and the bottom painted just before the purchase. To me, this would indicate a transducer problem possibly interference from bottom paint? Some of the readings agree with the chart plotter (the deeper ones).

The Data Marine instruction book is of no help at all. The book is extremely basic. Has anyone out there had these problems?

Bob Morrison
E-34 Terra Nova Hull # 15

Dmi ?

You might want to troll your questions past someone at the surviving Datamarine products company.
http://www.dmimarine.com/

Loren

ps: edit: I second Tom's idea for where to start to trouble-shoot.

Bob - I would check to make sure the cable connection to the meter is clean and properly connected, and then check for kinks or abrasion on the cable.

Does the transducer go all the way through the hull or is it glued to the inside, or some other arrangement? Sometimes there can be stray echoes from passing through different layers. Also, obviously, the transducer will point toward the bottom at different angles, depending on how it is mounted, what tack you are on and your degree of heel. Mine is only "correct" on starboard tack...

Bob:Some transducers mounted inside the hull have MINERAL OIL surrounding the transducer, inside a cofferdam. If that level is low, it will slop around and give erratic readingsIf the transducer is external to the hull, it may have ablative anti fouling paint with copper on the face. That will also cause problems.Good Luck.Bob

Erratic Depthsounder

Thanks guys. I went down to the boat today and beat my way through the winter clutter to check the points covered. I checked the transducer and it appears to be a through hull. There is a 2 1/2 " amber filled area at the top. I pulled the instrument out of the Edison Pod and cleaned and sprayed the transducer cable end. After the cleaning, it gave me readings of 10.8 feet, 17.9 feet 175 feet and MSD all at the dock. I will follow up with Loren's suggestion of talking to the Datamarine people.

Bob Morrison
Terra Nova