Lightning vs FPBs

Steve, Linda — Happy 2011 !!

There was a readers´ letter on this month’s Yachting World (btw, the same that brings your article – congrats!) mentioning that lightning strikes often seriously damage electric/electronic equipment on yachts … given that on the FPBs some basic functions are supported by electric/electronic stuff (fuel pumps, autopilot, etc), I was wondering whether you had to build some contingency for that? Moreover, are aluminum boats more prone to lightning strikes than their fiber/composite/wooden counterparts? Has Windhorse ever been stricken?
Best Regards,

Hi Alex:

Lightning is something that has been very much on our minds for many years. There is a lot of scientific debate on how it works, risks, and what to do to mitigate the risks.

We think that a metal boat provides two benefits. First, the hull and deck create a form of “Faraday cage” and does a better job of protecting items within it than is the case with fiberglass. Second, the metal hull has a lower tendency to build up the charge that launches the “leader” to the cloud which ionizes the air creating a path for the high power strike from cloud to boat.

Regarding basic systems, the damage that occurs is hard to predict. But a major strike – a really powerful one – is probably going to kill everything electronic. For the engine this means potentially the CPU and injection pump. Both have spares. The fuel system can be controlled manually, and the solenoids which send power to the pump(s) are easily replaced.

Should total pilot failure occur you would reduced to hand steering (or could carry a third system, wrapped in foil, as back up).

For electronics and comm gear, if you are worried, a hand held VHF, GPS, and sat phone should be stored in the microwave during lightning storms to add a layer of protection.

Personally, we  have never had a direct hit. But we have seen more than enough water strikes in close proximity to have a healthy regard for the risks.

Posted by Steve Dashew  (January 24, 2011)

3 Responses to “Lightning vs FPBs”

  1. Mike Parker Says:

    Hi Steve,
    The metal boat itself would seem to make a great Faraday cage and protect the contents.
    However external antennas are some of the most likely things to be struck, and their coax cables provide a direct path inside to the nerve center of the boat, the bridge. I bought lightning arrestors for the HF and two VHF radios. There are several competing brands, I believe I bought “Phasor”. I intend to mount them on an aluminum plate in the wet locker below the mast where coax cable enters the boat. Nothing is a perfect solution, but it will make me feel better 🙂

    Best wishes to you and Linda from FPB#1, Avatar, cruising near Noumea.
    Mike P.

  2. Daryl Lippincott Says:

    I have had several lightning strikes on commercial (alum.) aircraft. Usually with only small area of burned and perforated skin where the energy enters and leaves the aircraft.
    My land home is at 8750ft elevation and we get a lot of lighting strikes in our area. Most of us have lightning arrestors on our main disconnect panels. There is enough experience with these that it is expected that they will be helpful if the strike is on the power line “a ways away” but if the strike is near your box the electronics will be fried in spite of the lightning arrestor. Most “lightning rods” installed on domestic buildings are a not sufficent. They must have MUCH larger wires, connectors and grounds to absorb the energy than is normally used. One of my neibor’s works at a university as a machinist for research projects. He put a “heavy duty, all weather” lightning rod system on his house. Lightning hit one of his rods. It fried every electronic machine in his house. Blew the stones off his fireplace and left the main wall by the fireplace smoking. If I am going to have a lightning rod like an alum. mast on my boat, I will be careful to give lightning a robust path to follow to the water. I don’t want it arching through something (like a fiberglass hull) looking for a way to ground.

  3. Wayne Simmons Says:

    We experienced two back to back strikes on our steel cutter several years ago. I researched what’s out there and invested in the stainless steel pom poms that can be mounted on the mast head. They were created by an engineer out of Florida. The theory is that these stainless steel heads continually bleed off any built up charge on the boat and basically make your boat disappear whenever lightning is looking for a charged object to hit. I called our insurance carrier and they could not substantiate whether this is any better than chicken claws around your neck. But, he did say that in all his years of settling lightning claims, he has never had a claim from a boater who had one of these installed at his masthead. That was good enough for me. We have not had a strike since utilizing these. Our current ketch sports one on the main and one on the mizzen.