PS Advisor October 2010 Issue

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

The Standard Horizon 180i chartplotterís status page (below) features a signal strength bar graph in the lower left-hand corner. By using this graphical data and moving the unit around the boat, a user should be able to tell whether other devices are affecting its signal strength.


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 180iís 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

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 donít 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 itís 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.

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