PS Advisor: GPS Accuracy and Signal Strength

Do bimini-mounted solar panels affect a GPS?


I recently installed an 80-watt solar panel on my bimini. I am concerned that this may have reduced the positional accuracy of my GPS, a Standard Horizon 180i, which has an internal antenna mounted directly below the solar panel. Do solar panels cause interference with GPS signals?

Standard Horizon 180i

Images courtesy of Standard Horizon


Robert Boeckh
1978 Ericson 34t
Sidney, B.C. 

The solar panel should not affect the accuracy of your GPS or result in any irregular readings; however, it could potentially reduce the strength of the GPS satellite signal.

According to Scott Iverson at Standard Horizon, an easy way to determine whether the solar panel is impacting signal strength is to select the 180is GPS status page (see photo below), note the signal strength while the unit is under the bimini, and then move the GPS to an area on the boat that has a clear view of the sky and note the signal strength in that location; then, compare the two figures. Even a properly installed GPS can be subject to some form of interference, and several government agencies are continually working to identify and mitigate these effects. To paraphrase Mr. Twain, the reports on the death of traditional navigation and piloting skills have been greatly exaggerated.


Silicone Contamination

Standard Horizon 180i

As far as I know, the problem of silicone contamination on fiberglass has not been solved. Because silicone is added to many consumer products, including furniture polish and car waxes, it is becoming darn near ubiquitous.

A Web search turns up many “solutions,” notably fish-eye eliminator, but in my experience, these don’t work well or have their own drawbacks. Fish-eye eliminator, for example, further contaminates everything it touches. Using shellac as a primer/barrier coat is sometimes useful but its not foolproof. Has PS “been there, done that” already?


B.L. Sachs
Flicka, Hallberg-Rassy 31
Austin, Texas 

To get rid of silicone contamination on a fiberglass surface, your best bets are time (weathering), using a paint-specific washing detergent like Awlwash, and the not-so-green but effective habit of doing an acetone or MEK wipedown with a cotton cloth prior to sanding the surface.

Be sure to use clean cotton rags and change them regularly during the wipedown.

Also with this article...
Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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