Lightning mitigation systems - South Florida

RLB64

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19 hours ago, Rasputin22 said:

    Seriously, that was sort of a welcome response to a newbie. Used to be a lot worse!

     I do understand your concern and am close to making a similar decision for a 50 catamaran with a carbon wing mast for Hawaii. I doubt the lightning threat in Hawaii would be as high as in your Florida location. Not many places have the potential for lightning quantity and danger. I used to work for Gold Coast Yachts who have probably built more USCG certified cats than anyone anywhere and we used to make our own needle point lightning rods by grinding a sharp point on a 3/8" SS threaded rod and connect that to a heavy gauge copper welding cable down to a copper sintered plate on the outside of one of the hulls. Those plates are often used for radio grounds (SSB?) and have a lot of surface area for their footprint. 

   That seemed to work until two of our boats got struck by the same squall line within a few minutes of each other. One was an earlier trimaran design which was one of GC's first licensed boats and it was in its slip in a marina in St Croix. That mast was an epoxy/plywood fold up mast similar to the Gougeon Bros early wingmast and the lightning seemed to run down the carbon uni tows that had been added at the top of the mast to stiffen the cantilevered portion of the mast above the mast hounds on the fractional rig. From there the strike seemed to prefer the SS headstay as a path and ran down to the headstay fitting at the bow. In addition it seemed that there was enough carbon derivative in what I remember as a Technora spinnaker halyard but the cap shrouds shared a good portion of the strike. I am not sure if that boat had the ground plate mentioned above but the result was dozens of pinholes in the outer skins of the nomex cored hull and the mast above the hounds looked like a cartoon shotgun that someone poked their finger in the barrel as it was fired.  The mast came back to our shop and I helped with the repair and post-mortem but it took months before the hull got dried out enough from drilled holes and paper towel wicks. Coast Guard would come out every couple months or so with a moisture meter until they deemed the hull dry enough to restore the tri's certification.

    The other boat was a GCY53 catamaran which was by far the workhorse of the daycharter fleet and it was out sailing with guests on board just south of St Thomas. It was a newer boat and had no core to be an issue and the rod, cable and ground were probably much better suited to the task but it was where the cable had to make two right angle turns to go from the mast base on CL out through the main cross beam and then a hard turn down into the hull to the grounding plate below the WL. That much electric current just didn't like the hard turns and blew out in several places. Enough juice got into the house electrical network to run aft to the helmstation where it blew out the instruments and such. The skipper got a pretty heavy shock holding onto the SS wheel and when his head cleared the first thing he noticed was his knuckles on one hand were bleeding and he couldn't under stand how he got that injury until someone noted that the shattered glass bezel on one of the instruments mounted on the bulkhead that the helm was bolted had some skin on it. Seems that the spasm of the electrical shock had made the skippers muscles tighten up and the back of his had a hit the instrument. The event scared the shit out of crew and guest alike but there were a few holes in the hull or hulls and were taking on some water. Those boats had outboard motors on sleds aft and those electrics must not have gotten disable so they were able to strike sail and motor back to their dock in a hurry.

     There was a lot of debate in the charter community and our own staff and we switched to the 'bottle brush' type of lightning 'charge disperser' that was just coming into use at that time. I think the idea that the 'bottle brush' bleeds off the electrical potential of the boat through the multitude of small wires without making the 'feeder spike' to the clouds above that lets the Big Bang follow back down to the boat. I think that debate still goes on. Keep us posted on what you decide...

Forespar Dissapator


Thank you!  This is the anecdotal evidence I was vying for. Understood it’s a crap shoot. I just got off the phone with the CEO of EMP Solutions - Jay Kothari about their lighting mitigation system. $7000 for the orb and they have a $50,000 payout if you get struck.  I’m sure that language is pretty complex.

 

RLB64

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Let me correct myself on one point: carbon is by itself not a good conductor. So, yes ask the builder about that.
Thank you. Yes. Carbon is not a good conductor. Interesting that someone suggested that the mainsail track is what is used as the conduit. The mast is keel stepped. So, maybe have an open path to the bottom of the keel.  

As far as professionals, X-Yachts is building the boat, they have engineers and technical staff to problem solve. They sell boats all over the world, SE Asia comes to mind, I will express my concerns and see what they say. 
 

We will be in Denmark in August as the build will be approximately 70% done. I will personally ask about lighting mitigation to the project manager. 
 

Thanks everyone!
 

Capt. Ron

 

RLB64

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FYI - fiberglass/carbon fiber airplanes can be destroyed by a lightning hit. To be certified for IFR, which involved thunderstorms some days, the plane must have a metal mess embedded to conduct lighting currents. This system passes lightning tests run by the FAA.

A carbon mast with a heavy conductor would *probably* be OK as long as the lighting hits the top where the terminal is. If the conductor was inside the mast and lighting burrowed in from the side, not so much.

This website is interesting: http://www.marinelightning.com/Siedarc.htm

Mast builders might want to look at this:

https://www.compositesworld.com/articles/lightning-strike-protection-for-composite-structures

IMHO the biggest issue is NDT, if the mast is not obviously damaged, how can you be sure it is not damaged at all?
Been struck by lightning airborne a couple of times!

What is “NDT”, sorry if this is some text slang I don’t understand.

Capt.  Ron

 

slug zitski

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Thank you. Yes. Carbon is not a good conductor. Interesting that someone suggested that the mainsail track is what is used as the conduit. The mast is keel stepped. So, maybe have an open path to the bottom of the keel.  

As far as professionals, X-Yachts is building the boat, they have engineers and technical staff to problem solve. They sell boats all over the world, SE Asia comes to mind, I will express my concerns and see what they say. 
 

We will be in Denmark in August as the build will be approximately 70% done. I will personally ask about lighting mitigation to the project manager. 
 

Thanks everyone!
 

Capt. Ron
On large masts the mainsail track is mechanically fastened to an aluminum backing plate . 

your xyacht  will most likely have a Nordic carbon spar

these tracks are only epoxied to the mast…no fasteners, no backing plate….this would be a poor down conductor 

Xyachts  builds to customer preference.

lighting earth would be a customer preference 

you might contact Nordic Mast directly and ask what they recommend 

nordic mast is  part of Southern Spars

 

RLB64

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tall buildings help about the only good point to condo's or office buildings near water

we lived aboard in dinner key anchorage and watched the storms roll in with strikes on the builds

regular event but hits on boat masts were very very rare so rare I can't remember any

useless data but about 300 boats with alloy masts pre carbon era from the clubs the marina and those anchored out over more then 20 years time in a very stormy high strike area but ringed by high rize buildings
Very good to know. Thank you. We will be on the “new pier #7” spring of ‘23. Hopefully!!  Supply chain issues have pushed us back 6 months already. 
 

Capt. Ron

 

RLB64

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On large masts the mainsail track is mechanically fastened to an aluminum backing plate . 

your xyacht  will most likely have a Nordic carbon spar

these tracks are only epoxied to the mast…no fasteners, no backing plate….this would be a poor down conductor 

Xyachts  builds to customer preference.

lighting earth would be a customer preference 

you might contact Nordic Mast directly and ask what they recommend 

nordic mast is  part of Southern Spars
The carbon mast and boom are built by Axxon in Romania. 

 

RLB64

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Funny that my Name comes up as “Newbie”. I’ve been racing sailboats for over 40 years!  
35,000nm sailed. 
 

Better get that changed! ;)

 

JohnMB

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Been struck by lightning airborne a couple of times!

What is “NDT”, sorry if this is some text slang I don’t understand.

Capt.  Ron
Non Destructive testing, catchall for a raft of methods for examining structures without cutting them up into little pieces.... which tends to make them less useful as structures. Can include:

  • X-Ray
  • Ultrasound (lots of sub variants :))
  • Acoustic (tapping)
  • Eddy current (not much use in composites)
  • Thermography

And many more. For composites ultrasound is quite common, it will detect many flaws..... but it will also miss some, if there is a good acoustic connection across the flaw ultrasound will not detect it this has been an issue for bonded joints.

 

RLB64

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Non Destructive testing, catchall for a raft of methods for examining structures without cutting them up into little pieces.... which tends to make them less useful as structures. Can include:

  • X-Ray
  • Ultrasound (lots of sub variants :))
  • Acoustic (tapping)
  • Eddy current (not much use in composites)
  • Thermography

And many more. For composites ultrasound is quite common, it will detect many flaws..... but it will also miss some, if there is a good acoustic connection across the flaw ultrasound will not detect it this has been an issue for bonded joints.
I’m a Commercial Airline Pilot. 30 years in - 20,000+ hours. Been struck in a B737 and BE1900. 
 

Capt. Ron

 

slug zitski

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Non Destructive testing, catchall for a raft of methods for examining structures without cutting them up into little pieces.... which tends to make them less useful as structures. Can include:

  • X-Ray
  • Ultrasound (lots of sub variants :))
  • Acoustic (tapping)
  • Eddy current (not much use in composites)
  • Thermography

And many more. For composites ultrasound is quite common, it will detect many flaws..... but it will also miss some, if there is a good acoustic connection across the flaw ultrasound will not detect it this has been an issue for bonded joints.
Evidently the ultra sound is performed when the structure is new and a record is made . In future soundings are compared to this “as new “ sounding record 

 

RLB64

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Non Destructive testing, catchall for a raft of methods for examining structures without cutting them up into little pieces.... which tends to make them less useful as structures. Can include:

  • X-Ray
  • Ultrasound (lots of sub variants :))
  • Acoustic (tapping)
  • Eddy current (not much use in composites)
  • Thermography

And many more. For composites ultrasound is quite common, it will detect many flaws..... but it will also miss some, if there is a good acoustic connection across the flaw ultrasound will not detect it this has been an issue for bonded joints.
Thank you!  

 

kent_island_sailor

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I’m a Commercial Airline Pilot. 30 years in - 20,000+ hours. Been struck in a B737 and BE1900. 
 

Capt. Ron
Been hit in a PA-32 and a 737. The PA-32 lost all avionics for a bit, but a reset got it all going again. The 737 was fine, I was a passenger on that one, we landed at the next airport with company A&Ps, got  the plane checked, and went on after that.

 




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