Techno: Lightning Protection Systems

At left is an example of a properly engineered retrofit lightning protection system for a Nordhaven 55 [click the thumbnail for full size image]

When we first met him, Dr. Ewen Thomson was Associate Professor in Electrical Engineering, University of Florida, Department of Electrical and Computer Engineering. He left the university to launch his own company in 2004: Marine Lightning Protection Inc.

Ewen is a fellow Kiwi, a fine sailor, and so far as I know is the only researcher who has made a serious investigation of lightning safety in the context of boats floating in sea water and fresh water. As there is a wave big enough to capsize any vessel, there is the possibility of a lightning event so powerful that it may damage your electronics, possibly your vessel and endanger the crew. If you implement the results of the best research in this field you will have done everything you can to improve your chances.

Ewen’s IEEE paper was the basis for the revisions to the ABYC code related to lightning grounds: A Critical Assessment of the U.S. Code for Lightning Protection of Boats, Institute of Electrical and Electronic Engineers Transactions on Electromagnetic Compatibility, Volume 33, Number 2, pp. 132-138,1991. A less technical version of the IEEE material was published on Exchange as A New Concept for Lightning Protection of Boats [PDF].

The University of Florida hosts an online version of the Florida Sea Grant pamphlet Lightning & Sailboats. Steve recommends that you order hardcopy of the very useful pamphlet and 23-minute video here. Supplementary information is on the new company website here.

Ewen’s company sells a complete line of professional lightning protection hardware. You will not find any of the popular voodoo like “static dissipators”, or “early streamer air terminals”, for sale 🙂 Dr. Thomson is one of the rare souls brave enough to discuss the issue of so-called “lightning dissipators”. [hopefully we will not be getting letters from lawyers of companies selling these things – Ed.]. On the site, under the link Air Terminals, you’ll find a summary of recent research on these devices, including links to research by Dr. Abdul Mousa, also an IEEE Fellow, on this topic. On the site you’ll also find the latest information on optimal design of air terminals, which since Benjamin Franklin have been sharp. Wrong, blunt is more effective.

Catamarans are a special challenge to protect — but there is sound, scientifically correct advice on the linked page for multihull protection. The photo at left is NOT one of the vessels protected by Dr. Thompson, who explains:

Latest statistics Boat Us has released their latest statistics for lightning claims. These show that not only are there twice the frequency of multihull claims, compared with monohulls, but also the average claim is 67% higher. See all the statistics here.

· They do not come with an in-built lead ballast that can be used as part of the grounding system.
· Their two hulls mean that there is twice as much waterline to contend with.
· The bridge deck being suspended above the water introduces yet another vulnerability for sideflashes.
· The bridge deck suspended above the water also introduces a desirable grounding location away from crewed areas.
· The only viable solution is a permanent installation. See our FAQ page for some first hand accounts of
problems with temporary systems.

The bottom line is simple: whether you are building a new vessel, or retrofitting, go to Ewen Thompson’s Marine Lightning Protection for solutions.

4 thoughts on “Techno: Lightning Protection Systems

  1. Hello- Regarding the statement above “You may be able to order the Florida Sea Grant pamphlet; Lightning and Boats from the site, though I haven’t found the correct link. ”

    You can order the Florida Sea Grant booklet and video at or you can download the booklet from

    I hope this helps.

    Kim Wagner
    Florida Sea Grant College Program


  2. Pingback: Techno: Stan Honey on Marine Grounding Systems at Adagio Journal

  3. Kim,

    Thanks heaps for the real-time corrections. I have just updated this post to reflect your links. Please let me know if there are any other corrections required.



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