Dear Steve, We have a 60′ steel PH cutter, mast is 76′ off the water. We have had two back to back strikes, one year apart. The first strike took out the Icom VHF, the Simrad instruments and the autopilot. Just after the new electronics was installed (I literally mean 3 days), the boat took a hit at the yard in the water. The second strike took out the VHF again, and so far, the Charles Marine Isolation transformer (it was tied to dock power at the time). No other damage has been noted, and I am convinced that the strikes were well dissipated throughout the mast and hull.
Question: If I install the pom pom at the mast head, does it reduce the efficiency of the VHF antenna also on the masthead? Also, what kind of pom pom do you suggest? The electronics technician told me he could see a burn on a bolt head at the masthead where he thought the lightning bolt jumped from the antenna and ran down the mast. As a side note: both antennas were fried and literally exploded.
Thanks a million for the website, a tremendous resource.
Wow–two hits! Sounds like the damage was minimal, relatively speaking. Regarding the ion dissipating brushes, I have no scientific basis of making a decision. The last time I looked there were several sources, and I chose a pair made by Forespar–one for each mast—as they were quite inexpensive. Some of the manufacturers state they use these on radio and TV towers, with great success. But I have also seen scholarly arguments to the effect that they do not work.
As to any impedance between the brush and a nearby antenna, I doubt that would be an issue, as at the high frequencies used with VHF even a separation of an inch or two would be enough. Regards—Steve
Posted by Steve Dashew (November 30, 1999)
