Will a Mag do the job?


Full Member
Feb 9, 2006
If im looking for a shipwreck in an enviroment with a lot of earth megnetic/compas deviation work? The deviation comes from rocks with iron ore. I wondered if a gradiometer could be used?

In regards to gradiometer: Have anybody tried to rig the two magnetometers on a perpendicular axis to the heading of the boat. I think this would give a greater coverage when searching for the wreck.

What do you think



Bronze Member
Oct 10, 2006
Coastal, NC
Detector(s) used
Garrett Infinium LS, Garret Seahunter MK II, Geometrics 882, Marine Sonic SS
Primary Interest:
All Treasure Hunting
Deep Blue Marine has a triple mag array setup. Geometrics mags are made to be used in this manner especially the 880, with up to six on one array.

What kind of wreck are you looking for?


Bronze Member
Jun 14, 2004
Beaufort, SC
Detector(s) used
Garrett Sea Hunter Mk II

Areas with a high magnetic deviation can certainly cause problems with magnetometer surveys. But depending on the mag you are using and the software, you should be able to sort out deviations based on geomagnetic anomalies. A ferrous object will still give a noticeable trough and peak, where as localised deviations will give just a rise in the reading. Typically this rise will be quite noticeable and can be mistaken for a target. But good software and fine tuning the mag will eliminate these false targets.

The use of a gradiometer will still detect these rises and has no significant effect on the readings. The setup Brad is talking about is basically three cesium mags that still function individually but the software will perform the gradiometer calculations to determine if a target is to port or starboard or directly beneath the boat. The cesium mags are super sensitive and can detect a nail or spike at 30'. With this super sensitivity it also makes pinpointing a little tougher. Thus the gradiometer setup.

There are some other factors that need to be determined when performing a mag survey. One is the size of the object you are wanting to detect. This can have an effect on lane spacing as well as what you would expect to see in a deviation. I would expect that if you have an area of magnetic rock it could likely disguise small ferrous objects, but cannon and anchors should still give a clear peak and trough.

Robert in SC


May 13, 2005
Detector(s) used
Pulse X8 Fiher 1280 Garrett XL500
In those cases you have to use the combination of the Mag with Side Scan Sonar this is
the great shipwreck machine finder. I have the combination of a Klein 595 upgrade with
computer program and a Gem 19 M. I found shipwrecks in rocks,in sand etc.

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