Lightning protection for typhoon

[nscotia]

Any recommendations for lightning protection on a typhoon? Hook a battery charging cable to shroud and throw other end in water?

[Ken Cave]

When I had my Catalina 25, we used to carry
battery starting cables used to start cars, and hook
them up to the aft shroud and dump them in the water.

Never had a chance to try them out, but it was posted on the Catalina site that it really worked.

Another way to save your electronics during a lighting
storm is to store them in your microwave, if you have
one on board.

Hope this helps

Ken Cave
Cape Dory 28
Dragon Tale #227

[WaywardWind]

Prayer is no less effective than any other "lightning protection system" on any sailboat with a mast less than 150 feet high.

Literally, a fact of physics.

All else is hookus, pookus, hoolium and phoolium trying to separate the rubes from their bucks.

I will make no more comments on this issue (well, just one). ANYone wishing to throw their money away, please throw it my way, for I promise to pray for your boat everyday at 4:10 in the afternoon.

[Dick Spangler]

There is an interesting article in the current issue of Small Craft Advisor: "Lightning Strategies." It seems to suggest that it is a good idea to have a system of protection.

[WaywardWind]

There used to be a professor at a Florida university who trumpeted his self-proclaimed exceptional expertise in "lightning protection" and banged the drums looking for consulting contracts.

Much of what he proclaimed didn't closely match up with any known principles of physics, and he took some considerable flack from some with walls full of credentials.

After some considerable time and drum beating, he suddenly no longer worked at that university, and the tight-lipped limited response from that university as to why he was gone and where he might be found lead to speculation as to the extent of the sparks during and the underlying reason(s) for his departure.

Net net, lightning goes where it pleases, and there is not a thing a sailboat owner can to avoid a determined strike ... unless the sailboat in question has a mast higher than roughly 150 feet. If a lightning bolt has your name on it, it's gonna get ya.

That said, deaths from lightning strikes are far less often than thought. FROM MEMORY, I seem to recall the TOTAL number of lightning deaths in outdoor sports in the State of Florida each year (Florida has the most electrical storms each year in the continental United States) is about ten.

That ten includes deaths from outdoor sports lightning strikes in golf, swimming, kayaking, fishing, bicycling, boating, etc. The total on water boating lightning deaths tended to be "around" two per year.

There are more deaths each year in Florida of people killed in traffic accidents on their way to various marinas.

BTW, those "wire brushes" placed at the top of masts ionize the air at the top of the mast by several feet, in effect increasing the chances of a strike by making the mast "higher".

To ground or not ground a mast (and everything else metal) has a long, contentious history. No one on either side of the issue has any firm data (only anecdotal "stories") to support or discredit grounding.

However, magazine writers with or without agendas are forever writing articles "proving" something, and such articles appear all the time. Sharp-eyed readers have been known to notice that when yet another article appears, the magazine usually just happens to also that issue be running ads from companies selling "protection".

Prayer is no less effective.

[gk]

Where I sail, the Ty is usually the smallest boat, so I feel safe having lots of taller masts around. But really, when you look at all the boats in the marina, I know of only one strike there in 20+ years, and there are lots of T-storms. There seem to be lots more hits on golfcourses & baseball diamonds. There's a much greater chance of being run over by a massive power boat.

georgia

[sweet patootie]

I've always sailed offshore with a good length of 7x19 double-, or triple, clamped to the backstay above the turnbuckle swage. When threatened, just tossed the 7x19 overboard and prayed.

I don't think the jumper-cable idea is good. Not enough contact between the clamp and the shroud. Never been hit to prove my point, but that's OK with me.

KP

[Oswego John]

Hi nscotia,

Oh oh, I guess that I'm going to get in trouble again with my post.

I wrote a post several nights ago about my thoughts on lightning and sailboats. I did something wrong (par for the course) and it got lost somewhere and never did get sent in. Luckily for me because another contributor dissed exactly what I was going to say. But anyhoo, here's my thoughts.

The jury is still out on using a jumper cable clamped to the shroud with the other end in the water. A lot of them are made with #8 AWG or #6 AWG. Some of the cheaper ones use aluminum instead of copper cable. A direct lightning hit would probably produce a zillion copper or aluminum BBs. As was earlier stated, the spring jaw provides hardly enough contact from the shroud to the jumper.

ABYC rules have been amended to now require #4 AWG copper for adequate grounding. All connections and terminations must be mechanically and electrically secure.

Here's where I get in trouble. For years, many times I have mentioned the work of Prof. Ewen Thomson now retired from the Univ. of Florida. I have the highest respect for the results of his research dealing with lightning. Much of his work was conducted in Tampa, Fla., the lightning capitol of the USA. The Seminole translation of Tampa is "Sticks of Fire". (lightning). Below is a copy of an earlier post that I made on the subject.

****************************************************

Posted: Fri 3/5/10 1:57 pm Post subject: Lightning And Sailboats

--------------------------------------------------------------------------------

Below is a link to the publication "Lightning And Sailboats. It was written by Dr. Ewen M Thomson, who was a director of studies at the U. of Florida at Tampa.

The publication provides scientific answers to many questions that have been asked by sailors. It also disproves many old wives tales concerning lightning. I found it to be very interesting reading and hope it will be for many of you, too.

O J

http://edis.ifas.ufl.edu/sg071

Best regards
O J

[WaywardWind]

That's him.

As Good Ole Abe said, "... and you can fool some of the people all the time."

Professor Erwin Cory makes anecdotal statement after anecdotal statement, all poised as scientific fact.

It's been donkey's years since I've read Prof Cory's drum beat to sell his "services", but I seem to recall he makes no mention whatsoever that a bend in a grounding cable means the lightning "juice" is almost certain to "jump" outside the cable and travel through the fiberglass. Did he not know that, or did he "conveniently" forget it? Did he not know that the greater the bend the greater the chance of a jump?

Also, Prof Cory makes NO distinction between 1 million volt strikes and 100 million volt strikes. And there IS a difference in effect on the sailboat. Did he somehow not know that?

And other information of "slight import".

People are afraid of lightning and Professor Erwin Cory made money off those people without supplying anything other and better credentialed professors felt useful information to know.

Literally, prayer is no less effective. If one wants to buy some protection, buy a St. Christopher's medal.

If your mast is less than 150 feet high, there is not a thing you can do which is more effective than prayer.

Unless, of course, you send me the money and I'll do the praying for you at 4:10 every afternoon during the summer. -grin-

BTW ...

" When the tip of the stepped leader is about 30-100 yards above ground level, another spark, this time positively charged, is launched from the ground." ...

... is utter horse hockey. Hokus, Pokus, Hoolium and Phoolium.

Interesting is that in paragraph #16, he flatly states that ancedotal evidence of "nine marine surveyors in Florida" found that 34% of the sailboats (they surveyed) had lightning protection systems" while 29% of those sailboats serveyed for lightning damage to boat and/or equipment were grounded.

Nine surveyors, of 1,800+ sailboats surveyed, 600 or so were grounded, and of those 600 or so which were grounded, not quite 600 sustained lightning damage to boat or equipment bad enough to prompt an insurance claim. (Professor Cory says ALL sailboats in florida sustain lightning strikes.)

THAT is the case for ALL such investigations into "lightning protection systems via grounding". ALL ancedotal, AND not enough difference to be statistically significant.

[bottomscraper]

Professor Erwin Cory makes anecdotal statement after anecdotal statement, all poised as scientific fact.

Reminds me of someone else we know.

[WaywardWind]

Be afraid. Be VERY afraid.

Or, protect your boat in a manner no less effective than any other. Send me the money so that I pray for your boat every afternoon at 4:10.

[nscotia]

Thanks for the responses. Years ago(1972) a typhoon that I had at the time was moored at the Palmer cove YC in Salem, Mass. It actually got hit. It left a small hole at the water line beneath the port shroud. I was hoping there was a new solution for my newly acquired typhoon. Looks like prayer and more church visits will have to do.

[Oswego John]

Thanks for the responses. Years ago(1972) a typhoon that I had at the time was moored at the Palmer cove YC in Salem, Mass. It actually got hit. It left a small hole at the water line beneath the port shroud. I was hoping there was a new solution for my newly acquired typhoon.

I don't know about a new solution, but there is an old solution. if you will, that affords a boat owner a better chance of not having his boat totally destroyed. That would be the installation of a copper discharge system.

Of course no one knows for sure just exactly what happened in your case. My guess is that lightning hit your mast, ran down the mast to the bilge and cross fired to and through the hull seeking discharge at the waterline

Prof. E Thomson
Lightning Interaction with a Sailboat
Attachment
As the negatively-charged stepped leader moves downwards, it induces a positive charge on the ground below. When the tip of the leader is about 30-100 yards above ground level, the induced positive charge becomes so concentrated that a new spark forms at the ground, as shown in Figure 2. This positively charged spark is the crucial process as far as the attachment to a boat is concerned. If it starts at the tip of a boat mast, then lightning strikes the mast. Unfortunately, there is no scientifically accepted technique to prevent this spark from forming. Even if a device were effective in diverting the attachment spark, it would not be a good idea to mount it on the masthead as the attachment spark may start elsewhere on the boat or crew. The likelihood of lightning attaching to the masthead is a safety feature as far as the crew is concerned.
Consequently, lightning protection means minimizing the damage caused by lightning in the event of a strike, rather than preventing a lightning strike. In general terms, a protected boat is one in which there is a continuous conducting path from the water to the mast tip. The current needed to feed the attachment spark is conducted through the protection system from the water. That is, the path that the lightning takes in the boat is forced to be that of the conductors in the protection system. If this conducting path is not continuous, for example, in a boat which is not well grounded, there is little difference as far as the top of the mast is concerned. The attachment spark still begins there as this is where the positive charges have concentrated. The difference is what happens where the conducting path, the mast, ends. Since current cannot flow from the ground to feed the growing attachment spark, a negative charge accumulates at the base of the mast and eventually arcs across in the general direction of the water or a nearby conductor. (For this exercise, crew members are conductors!) The result is an unharnessed electrical discharge between the bottom of the mast and the water.

There isn't much anyone can say or do in regard to a direct lightning hit. However, with the installation of a direct electrical path between the surrounding water and the top of the mast, a boat owner increases the safety factor of the crew and lessens the potential damage to the boat.

I might add that Dr. Thomson is the author of additional studies on lightning. Some of his highpoints are the use of stranded (multiple twist copper conductors) and the avoidance of bending sharp angles in the copper grounding cable. You might ask, why use stranded copper instead of solid copper conductor.

The answer is "Skin Effect". The higher the voltage, the closer the current travels to the outside of the conductor. Something like centrifugal motion. With a solid conductor of a given circumference, there is a certain amount of exterior surface. By the use of multi-stranded cable of the same circumference, the many individual strands provide an exponentially greater surface area to aid the transfer of the abnormally high voltage of lightning and to lessen impeding the current flow.

Sharp bends in the grounding conductor are frowned upon. Minimum of bends are encouraged. Of course, some bending is unavoidable. Our in-house electrical/electronical guru. Larry DeMers, recommends no larger than 30° bends. I would assume that three 30° bends in close proximity would be better than one 90° bend. Forget the aesthetics. Provide a gradual, obtuse bend rather a sharp 90° elbow.

There are many thoughts by many individuals on the subject of lightning, especially with its concern to sailing. Who is to say what is the definitive answer or solution to this ages old phenomena. Just to blow your mind, when you search for "Lightning" in the CDSOA archives, you are likely to find, at this reading, 226 individual threads.

Best regards,
O J

[WaywardWind]

Gee, the good Professor Erwin Cory is talking about "centrifugal" electricity? Can anyone say "Snake oil"?

"If you can't dazzle 'em with brilliance, baffle 'em with bull hockey."

Note to Professor Erwin Cory: There is NO force in nature called "centrifugal". CentriPETAL, yes, but no centrifugal.

Note #2 to Professor Erwin Cory. Electricity has no mass, therefore there can be NO centripetal (or alleged centrifugal) force.

Note #3 to Professor Erwin Cory. Stranded or solid core wiring, no one worries about the current carrying capacity of one compared to the other.

Geesh.

BTW, "Professor" Erwin Cory started out as a high school science teacher and never did get to be a full professor at any university. Tutor (tutor???), lecturer, research assistant, "provisional visiting assistant professor" (all of which mean barely paid), "assistant professor" (means low-paid part-timer), and associate professor (which means can be terminated at any time for any reason). Professor Erwin Cory left the academic world (apparently for good, and with no reason given) 32 years after he graduated college (which presumably means in his early 50's), as compared to most college professors who continue on into their 80's when they are carried out in a pine box.

[Oswego John]

Hi WWW,

Something like centrifugal motion

I'll stick with my original statement. Centrifugal means away from the axis or core. Centripetal means toward the center.

The higher the applied voltage, the greater the effect of *whatever you want to call it* is towards the outer surface, or skin.

Best regards,
O J