Hi, everyone.
Lightning seems like one of those deadly sailing dangers, like rogue waves, whale capsizings, meteor strikes and extra-terrestrial kidnappings, for which there is no real-world protection, so it simply isn't discussed much. Thus the Catalina manual pretty much punts on the subject, and a search through these forums yielded me no results. Maybe I'm not using the right keywords?
In any case...
Searching google for "lightning sailboat", I found some interesting articles on lightning protection for sailboats.
This was the best article I could find:
[url]http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf[/url]
This was good, too:
[url]http://www.practical-sailor.com/newspics/0808-Lightning-Dissipators-FINA...
And this as well:
[url]http://www.nasdonline.org/docs/d000001-d000100/d000007/d000007.html[/url]
Note in the above how installation of a system may actually INCREASE your chance of being hit. Yikes!
Also note in the above the recommendation that the path to ground be in a straight line. This is in synch with the recommendation in the Catalina 36 owners manual (Pre-MK2).
Also note the recommendation that the in-water ground connection be "any submerged metal surface with an area of at least one square foot".
Thinking about all these articles' recommendations got me to thinking about the best way to protect my C36. The lead keel appears to be an adequate "submerged metal surface", so what if I bolted, say, a thick stainless steel rod to the mast and the forward keel bolt, and then clamped a sacrificial zinc to it, to prevent corrosion due to dissimilar metals (the aluminum mast and the SS rod). Better would be a thick copper wire (No. 8 AGW mininimum), since I could bend it into the proper curve for the stated requirement that "Any bends in the conductor should have a minimum radius of eight inches".
Again, the zinc would sacrifice before the SS keel bolt, the copper wire and the aluminum mast, right?
A hesitation I have about this is that a lightning strike might blow a hole through the keel at the keel bolt, or from the mast step through the hull, if it saw that as a better path-to-ground.
The Catalina manual stated that the best system they can think of, would have a copper rod leading over the side of the boat, attached to one of the SS shrouds. But they don't say anything about the one square foot metal grounding plate, and they admit that their solution isn't very good.
Do any of you have better ideas on this subject? Do you know of anyone who has installed a protection system that they can PROVE will work (note the "Why You Can't Fool Thor" article above) and that's reasonably maintainable?
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
A few quick notes:
1. Last time I researched this, there was wide disparity in approaches and no consensus on what might actually work.
2. Investigations after lightning strikes have revealed much strange and unpredictable behavior.
3. If you are going to use a conductor from the mast to the keel bolt (as our boat has), it should probably be at least a 3/0 AWG size (about as big as your finger). Despite what the one article stated, an 8 gage wire seems pretty tiny to be used for lightning.
I am not even close to an expert on this, so take my comments for what they are.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
Park next to a taller ship
LOL
Bob, LaRainne and McKenzie Robeson
1985 Std Rig C-36, Hull #374
San Pedro, Cal
Sailing the So Cal Islands and coastal ports from San Pedro south to San Diego.
A good friend had a Bucanner 27 stuck by lightning, boat was bonded and the mast was one of the shortest of 50+ boats! Inbeeded his windex in a c-30 hull three boats away, blew 100+ holes through the hull on the waterline and burned her electric panel into a bulkhead on the other side of the cabin. Totaled, he was glad that he had no great love for her---sailed like a slug!
Someone told me if your boat has been through thunderstorms and not been struck then some insulation from not being grounded may bring some immunity. We have sailed through many sudden thunderstorms with 100's of cloud to ground lighting all around us. SCAAARRRY! a 1" Dia. bolt of lightning has millions of volts of force and so much current just from that dia of electricity that I don't see anything other than a faraday cage (ovens, bimini frames) that could offer any protection and a direct hit must be catastropic no matter what protection!:eek:
Spanki & {Russ 12-8-1949/9-6-2010 R.I.P Butch}
s/v Spanki 1993 Catalina 36 #1224
"Don't worry, Be happy""Sail your life away"
Two years ago my boat was struck by lightening while at the dock. No one was aboard. I had not (and still have not) added any lightening protection to the boat because everything I have read only confuses me as to what to do. The consequence of the lightening strike (My mast was the tallest in the immediate vicinity) was that nearly everything electrical and electronic on the boat needed to be replaced from the antennas and wind instrument at the top of the mast to the instruments at the helm. this included the batteries, charger, tv, stereo, wiring in the mast, exterior lights and most interior bulbs and some lights. There was no structural or other physical damage. The repair cost $24,000 and BoatUS insurance paid for all minus the deductible.
I wish I knew what lessons to learn from this regarding lightening protection. I think even if everything was grounded, the damage to the electronics would have been the same. I am interested in knowing if others disagree on this point. I always thought the point of grounding was to avoid damage to the hull. I would love to know whether anyone else has a different point of view on this.
Elliott
Elliott Milstein
Collaboration #1469
1995 C-36MkII
Port Annapolis Marina
Elliott,
Nothing I remember reading suggests that you can protect electronic equipment with anything other than (perhaps) disconnecting the equipment and storing it in a Faraday cage (a metal oven is often quoted as a decent substitute).
In my inexpert opinion, I think the best you can hope for is to conduct the strike's power to the water with minimal structural damage to your boat. Replacing all the electronics is almost a given in a lightning strike. Not having a hole blown into your hull below the waterline would be the thing you are most hoping to avoid.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
As a Kansas boy now residing in the Pacific Northwest, I have to say that the biggest (and perhaps only) downside to living in this perfect corner of the planet is that we don't have knockdown drag-out thunderstorms. I miss them. But as a former aviator, and now a seaman, I really didn't/don't appreciate being exposed to them, preferring to enjoy them from a place of refuge.
One thought I had was to carry a set of battery cables, and if a storm threatened, to clamp them onto the shrouds, letting the other ends hang in the water. It's pretty low tech, but has the advantage of being cheap, and of bypassing the poor-conducting lead keel entirely. Clearly it wouldn't be a long term solution, but it might be just the comfort you need someday.
Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
Actually, the battery cable idea is pretty close to what the Catalina manual recommended, but they admit it is not a great solution. I'm wondering if the battery cable plus an in-the-water ground plate (minimum 1 foot square) would be a great solution.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Quite coincidentally, I was caught out in a thunderstorm on the Chesapeake on Sunday. The forecast was for widely scattered thunderstorms in the afternoon so we set sail from Oxford to Annapolis early in the morning and the storm arrived mid-morning. Once it was clear that there was something happening, I doused the sails, brought out life jackets, set the autopilot and told the crew to stay away from metal. We mostly had heavy rain but there were a few streaks of lightening from sky to water, luckily somewhat in the distance. At some point I checked the GPS and discovered that we were headed south instead of north so I wonder whether the electrical storm did something to the autopilot. Otherwise, all went well. Given this discussion thread, it did feel like I tempted fate by telling my story. Could it be that the old adage that lightening doesn't strike the same place twice will protect me? Ha!
Elliott Milstein
Collaboration #1469
1995 C-36MkII
Port Annapolis Marina
I think Elliott hinted at a solution to the topic of this thread. [I]How to Protect a Catalina 36 from Lightning[/I].
Park next to a boat taller than yours and with any luck it will be his problem and not yours.
Bill
s/v Lucky
1984 MK I Hull #266
San Antonio, Texas
Everybody I know who's boat was hit by lightning was struck while their boat was tied up at the dock. Maybe the solution to avoid being hit by lightning is to take the boat out in the harbor when a lightning storm approches. :)
__/)__/)__/)__Capt Mike__/)__/)__/)__
Punta Gorda Florida
1990 Std WK M35 Hull #1050
After several weeks of study on this subject, I believe that Nigel Calder's approach in his "BoatOwner's Mechanical and Electrical Manual" is the best. It pretty much concurs with Dr. Ewen Thomson's approach and Dr. Thomson is probably the foremost expert on marine lightning in the world today:
[url]http://www.marinelightning.com/profile.htm[/url]
Essentially, Calder's approach is to create a primary down conductor, grounding the aluminum mast to the keel bolts for the main strike, plus secondary down conductors for the shrouds/chainplates (since lightning doesn't always hit the mast), and then finally bond any large metal objects within 6 feet of the down conductors, plus the engine no matter where it sits.
The down conductors should all be as vertical as possible. He recommends against any horizontal down conductors running through the boat, say, from the keel bolts to the prop shaft. This avoids lightning running through the boat. I'm still debating the forestay and backstay with myself.
This is as good of a "people protection system" (vs electronics protection) as I can find. (Again this is all in Calder's book.)
There is also a good article on this subject in this month's Ocean Navigator. Unfortunately, unlike this lucky family, we are not in an aluminum boat (which would act like a giant faraday cage).
I have completed the primary down conductor. I used copper strap instead of #4 AWG wire, as it apparently conducts lightning better (from my research including Calder). Since I have a dry bilge now, and plan to keep it that way, I'm hoping that galvanic corrosion will not be much of a problem. Will of course keep it all sprayed with Corrosion Block.
Note in the pics that I have since changed out the nylon lock nuts with stainless steel lock washers.
Next project will be the secondary down conductors. Going to use #4 AWG marine wire for those, and #6 AWG for the bonding of the other metal large objects in the boat.
Granted this is all debatable, and lightning may still kill me but at least I have tried to protect myself and family with the best scientific evidence I can find at this time.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Or at least, be near a better grounded mast, not necessarily a taller mast. At the boat club I belong to, we seem to average about one boat a year hit in the mooring field. Being the taller mast in a mooring field, seems to have nothing to do with being hit. Usually no one is on the boat and the lightning strike usually goes unwitnessed. Later the unlucky owner discovers all the electronics are fried or the boat is setting a little lower in the water due to pin holes in the bottom.
I don’t think anything other than a Faraday cage is going to protect electrical equipment in close proximity to a lightning strike. Creating a “path” to ground may help to avoid pin holes in your bottom, but will certainly increase your chances of being a more attractive target.
The only thing that appears to work with any certainly is good insurance and to stay away from any potential conductive paths to ground.
On the other hand I have a friend who was holding up a sun shower bag while his wife was taking a shower on the foredeck , with blue skies over head. And BANG, the boat
got hit from a lightning strike from a cloud off in the distance. If I see any clouds around I keep my distance from them. Some people and/or boats are just more attractive.
Nile Schneider
Mañana C36 #1798
Lake Champlain, VT
From: [url]http://edis.ifas.ufl.edu/sg071[/url]
....which is Dr. Ewen Thomson, whom Nigel Calder refers to in his own book, as mentioned above:
"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 [B]continuous conducting path from the water to the mast tip. [/B]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.
According to the above argument, the likelihood that lightning will strike a boat does not depend on whether the boat is well grounded or not. There is some support for this in the experiences of marine surveyors. Nine marine surveyors in Florida, each of whom had surveyed more than 200 sailboats in their career, reported that between 2% and 67% (on average 34%) of the boats they surveyed for any reason had a lightning protection system. Of the boats that they surveyed because of a lightning strike, they reported that between 0% and 67% (on average 29%) had a protection system. While the individual estimates varied widely between surveyors, [B]there is no support for the argument presented by some sailors that they should not ground their sailboat since it will increase the chances of it being struck by lightning. [/B]"
...so we have both Thomson and Calder and ABYC all saying that grounding and bonding for lightning, while it may not guarantee protection, certainly provides SOME degree of protection with NO additional risk of being struck. There is only a cost of time, wiring and connectors.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
From Calder's book p 222:
"One school of thought holds that the process of attracting charged particles to the lightning rod actually increases the possibility of a strike, and therefore a lightning rod should NOT be fitted to a boat. The consensus of expert opinion is that this position is not supported by the evidence."
Granted his "consensus of expert opinion" may just be Dr. Ewen Thomson, but I doubt it. Calder is pretty thorough and like myself, he is (was at the time?) a liveaboard and thus the lives of his own family are at stake here.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Ben,
You are on the right path. Try to MINIMIZE DAMAGE TO HULL AND HUMANS as best you can.. You CAN'T DO ANYTHING to prevent a strike and there is also NOTHING you can do to prevent damage to electronics except have good insurance. If anyone tries to tell you that you can protect electronics or "prevent" a strike they are full of it and most likely trying to sell you somehting...
I work with multiple lighting strikes per summer, and our own boat was hit back in 2008. She is wired to far better standards than Calder or the ABYC suggest and is using dual 2/0 conductors from mast base to keel bolts. She suffered ZERO hull damage and ZERO wiring damage in the strike.
Everything electrical was toasted including multiple devices not even plugged in. We were hit so hard even our compass was knocked out of calibration. We lost the EPIRB (not plugged in), and iPod (not plugged in), four GPS devices (two of which were not even plugged in) a laptop computer in its padded case (not plugged in) and a few other devices that were not even connected. All in all it was 25k in total damage but no wiring damage (other than some very small NEMA wires in close prox to the VHF).
In my own small pool of lightning strikes:
* I have had more fuzzy bottle brush boats hit than ones without.
* I have had more "unbonded" (lightning grounds) boats hit than "bonded/grounded"
* I have seen significantly less hull damage on boats using a primary/secondary lightning bonding system where the main mast down conductor and rig conductors goes to a keel or underwater copper strip.
I am still working on a large J-Boat that was hit last September. This is a fuzzy bottle brush boat but also one that had adequate primary and secondary down conductors. She too suffered zero hull damage and because she is cored was fully examined by thermal imaging over the winter. The owners were on-board during the strike, and said it was shotgun loud, but they were un-harmed.
Lightning "protection" is sort of a misnomer IMHO because there is NO protection from lightning. I prefer to think of these systems as "damage minimizing" strategies. A well installed system of down conductors can minimize the potential for hull damage.
This unbonded boat was hit the same night as ours was. The hull was full of holes and this is just one of the clusters of holes..
[IMG]http://www.pbase.com/mainecruising/image/143541418.jpg[/IMG]
-Maine Sail
https://www.marinehowto.com/
Yes, I'm writing off the electronics. Maybe putting some in the oven, which some say acts like a faraday cage. Electronics are replaceable; people are not.
I wonder if my four copper straps would be equivalent to two 2/0 wires.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263
Wow Rod; that's quite an impressive and awe-inspiring photo! Out of curiousity, what make of boat was that - and why the exit holes there?
---- Howard & Linda Matwick ----
--- S/V "Silhouette" - Nanaimo, BC ----
--- 1999 C36 MkII #1776 M35BC ---
It was a Cal. The reason the holes are there is that lightning was triyng to find "ground". The spar was not bonded to the keel, the stays were not bonded so the lightning took the spar to the deck via VHF cable & other mast wiring then entered the boat and went through the wiring. The holes were where any wires were against the hull and the lightning blasted through the hull to find ground.....
This sort of damage I find to be much more common in boats that are not well bonded. Keep in mind that many boats may be "bonded" but the connections so old and decrepit that it is not providing a good low resistance path to Earth especially in a strike.... Just because a boat is bonded does not mean it is well bonded..
-Maine Sail
https://www.marinehowto.com/
I'd like to add a pair of 2/0 cables from my mast base to the keel bolts. Where would I find a 2/0 battery lug that will fit a 3/4" keel bolt? I've checked around and the best I can find are 1/2". Is 2/0 cable preferable to copper strap?
The first year I had a boat ('86) I got caught in a thunderstorm and dropped anchor near another small sailboat. There was a tremendous bang, loudest sound I've ever heard. I threw myself on the cabin floor in fright.! Found my boat intact, but it had hit the nearby sailboat, traveled through it's wiring and vaporized the plastic depth sounder transducer. Boat was taking on lots of water and was towed to a nearby marina and hauled. I would not like to have that experience myself..!!!
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
Check with a welding supply company or someone like Interstate Battery.
Nile Schneider
Mañana C36 #1798
Lake Champlain, VT
[QUOTE=plaineolde;18039]I'd like to add a pair of 2/0 cables from my mast base to the keel bolts. Where would I find a 2/0 battery lug that will fit a 3/4" keel bolt? I've checked around and the best I can find are 1/2". Is 2/0 cable preferable to copper strap?
The first year I had a boat ('86) I got caught in a thunderstorm and dropped anchor near another small sailboat. There was a tremendous bang, loudest sound I've ever heard. I threw myself on the cabin floor in fright.! Found my boat intact, but it had hit the nearby sailboat, traveled through it's wiring and vaporized the plastic depth sounder transducer. Boat was taking on lots of water and was towed to a nearby marina and hauled. I would not like to have that experience myself..!!![/QUOTE]
The best bet is to drill a short piece of copper bar stock ( I by mine from McMaster Carr) with a 3/4" hole on one end and a 3/8" hole on the other to accept the battery cable. The copper stock drops over the keel bolt and you then add a second keel nut over it... As always coat everything liberally with a product like No-Ox-Id..
-Maine Sail
https://www.marinehowto.com/
Hi, all.
I have now pretty much completed my secondary down conductors - at least the hard part. These all lead from the lowest part of the 6 chainplates to the closest keel bolts.
The hardest and scariest part of this job was drilling the holes through the starboard hull liner. What makes it so hard is that if you drill too high, you expose the wire and the hole above your floorboards but if you drill too low, you can accidentally drill right through your hull! ...and you can't easily visualize where you are drilling. It's all way up in an impossibly hard spot. Obviously better to err on the high side, but while doing this job, I often cursed Catalina for not giving us a decent place to make this critical enhancement. The first picture shows where I made the holes for the aft two wires (4 awg per Nigel Calder) in the starboard lower locker (just starboard of the mast).
Be aware that after drilling the holes, you now have a new potential leak into the starboard lockers if you are heeled hard on a port tack AND you have significant water in your bilge. To mitigate that risk, I sealed the holes well with 3m 4000 as you can see in the pic. Hope that does the job.
I'm not totally happy with the curves in the wire, as you can see in the pic. Lightning wants to travel in as straight line. Some of the curves I can prevent by shortening the wires a bit anytime I wish, but initially I was very afraid about make the wires too short (coz they're EXPENSIVE!), in which case I could not later shorten them if I get corrosion at the ends...or just screwed up my initial measurement on the short side. Usually better to have too long a wire than too short. Other curves cannot be helped. I just had to go around too many bulkheads and boxes and stuff. Again Catalina let me down there.
Next I plan to bond the engine, the sink, the fuel tank and the stove to the aft keel bolts with 6 awg wire, all of which are close to the mast. This again is per Nigel Calder.
After that, I plan to strengthen the connection at the keel a bit per Maine Sail's suggestion above about the copper bar.
...but at least I'm sleeping without so much fear of these almost nightly thunderstorms.
Ben Ethridge
Miami, FL
1984 MK1 Hull# 263