Cruisers Forum
 


Join CruisersForum Today

View Poll Results: What do you think of lightning protection?
Do you think lightning protection systems work? 11 35.48%
Do you think lightning protection is a waste of time and money? 5 16.13%
Do you think a prayer and good insurance is the best protection? 15 48.39%
Voters: 31. You may not vote on this poll

Reply
 
Thread Tools Rate Thread Display Modes
Old 12-06-2007, 16:48   #16
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,573
Images: 240
I've never heard a reputable scientist advocate bottle brushes,
and
the blunt tip air terminal has been generally advocated since the late 90's. I believe the various "Standards" commitees adopted blunt rod recommendations about 2000.
I'm sorry if I seem abrubt, but I've previously presented an extensive review of the literature - and there's not a lot of controversy (amongst the "informed") about these simple alternatives.
__________________

__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 12-06-2007, 21:02   #17
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
"Did you ever get the feeling they have not perfected the science behind lightning strikes yet?? (smile)."

On the contrary. The science behind electricity and lightning strikes is extremely advanced. As an "airplane" person I am very familiar with the subject as relates to aviation. Commercial airplanes are struck all the time - everyday! I am somewhat bemused(?) by the boating community where there is a tremendous amount of pseudo science and old wives tales. Electricity is very predictable.

We just had a sinking 4 weeks ago here at our club. A J24 mast was struck during a thunderstorm and the boat was holed and sunk on teh mooring in 40 minutes.

After haulout I took a good look and it is clear the strike carried down the mast and jumped off the mast below decks about 18 inches above the step. The strike went forward and blew out a 3 inch diameter hole about 5 inches forward of the mast. There were several smaller holes nearby suggesting that the strike separated upon leaving the mast.

The practice of tying all the metal bits together is called bonding. In aviation if you don't bond everything together the strike can jump across rudder bearings effectively welding them in position.

So the basics of any plan require all the metal to be bonded together. Secondly the energy needs a path to ground. It will take the easiest path to ground so the path you provide has to be low resistance, hence large diameter wires and copper plates and so on.

I read that one argument for not bonding to the keel is that a less resistant path may exist through the hull of the boat rather than across corroded keel boats. That's why the plate on the hull is recommended because the water is the closest path to ground and you are trying to make it also the least resistant.

The heat generated by a strike is important. This is why it is especially critical that filled keels and foam filled hulls not be used as grounding planes. The heat expands any moisture inside and we all know what happens when water heats up.

This is exactly what happend to the J24. Several of the smaller holes look like "explosion" holes. We surmise that captured moisture expanded and blew out. In fact event the main hole showed very little signs of arcing or burning.

I personally think the likelihood of a strike is tiny. But so is the likelihood of a sinking at sea and no one would consider a crossing without a lifeboat.

It's expensive but If I go across an ocean I will have a properly bonded boat with a low resistance path to ground.
__________________

__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 14-06-2007, 13:13   #18
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
I would think doing something like 44 cruising cat recommends, take a big 0 gauge cable straight from the bottom of the mast down and through the drain hole in the anchor locker to the water with a large plate at the end.
schoonerdog is offline   Reply With Quote
Old 14-06-2007, 13:44   #19
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
Quote:
The science behind electricity and lightning strikes is extremely advanced. As an "airplane" person I am very familiar with the subject as relates to aviation. Commercial airplanes are struck all the time - everyday! I am somewhat bemused(?) by the boating community where there is a tremendous amount of pseudo science and old wives tales. Electricity is very predictable.
In how to protect Aircraft, that maybe true. In understanding electricity, that may also be true. In lightening strikes to ground sources, that is absolutely untrue. Plus to add, it is not JUST the electrical path that is the concern. The ability to condute and electrical flow to somewhere is very simple. But in a lightening strike, we have many aspects other than just an electrical flow, that majorly differ between each and every strike. The magnetic feild is just one of them. RF energy is the other. A bolt of lightening is complex. It is both AC and DC. It is RF. It has a magnetic feild. It is emense heat. It is an instantaneous flow of extreme high current and voltage. It causes any "insulator" in it's path to become a dielectric causing it to become a capacitance. This is one of the single most factors in seeing strange effects of high frequency energy and static energy bouncing and reflecting and defying simple electrical theory around the insides of what most would deem an insulator, being the inside of a plastic boat.
The ability to protect a metal envelope as in an aircraft is easy. The ability to protect a boat that is on the strikes path to ground is very different.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 14-06-2007, 16:14   #20
Registered User
 
Viking Sailor's Avatar

Join Date: Nov 2006
Location: San Francisco Bay
Boat: Fantasia 35 - s/v Feeling Good
Posts: 1,074
Quote:
Originally Posted by Viking Sailor
Does anyone have first, second, or even third hand knowledge of a Dynoplate failing or exploding due to lightning?
Well it has been two days since I posted this question and there has been no response. I am also a little surprised at the lack of interest in this subject. As of this posting there have been only 248 views. Strange! You would think that as a real hazard to crew there would be more interest. Especially since there is sufficient knowledge to mitigate the risk to the crew from a lightning strike.

While we wait for Cruisingdad to check his source for an answer to the original question I will pose a new question.

Has anyone with a Dynoplate installed been hit by lightning?
__________________
Viking Sailor is offline   Reply With Quote
Old 14-06-2007, 16:30   #21
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Quote:
Has anyone with a Dynoplate installed been hit by lightning?
I have one and have not been struck. My neighbor with a bottle brush has been hit twice (both times in the slip a few boats down from me). I think it is a myth to assume that lightning strikes have a lot in common because they take many forms, shapes, and intensities. They don't all strike the top of the mast or any place else in particular while you might expect that they do. Once struck the path is never all that logical after the fact so the pattern of how they work is never always the same and not all that similar.

If you are looking for evidence that having a dynoplate is dangerous then I'm convinced you'll not find that either. I'm sure the dynoplate manufactures could not cover up that fact.

I'm sorry you were unable to find the answers to your lightning questions here but there are not many answers any place I've ever been either. Some things are not well understood.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 14-06-2007, 16:47   #22
Registered User
 
Cruisingdad's Avatar

Join Date: Feb 2007
Location: SW Florida now, then Bahamas and carrib 2010
Boat: Catalina 400
Posts: 143
Viking,

If you feel comfortable with using the plate as a ground, do it. It is your boat. I will ask Valiant this weekend about their experience. However, should they say "yes", how do you know it wasn't just a fluke? SHould they say NO, does it mean it has not or cannot happen? Thier comments will hold little value in determining the real potential for the plate popping.

Given the very small number of boats with plates that are grounded and have been hit (and of those that have taken it through the plate, I would not put a lot of credence in it either way. I will say, to this sailor perhaps, the logic behind it makes sense. THere have been many write-ups with the same conclusion, one of which I posted as a link above.

It is not to sound argumentative, but I will put it this way: Ever been to a gas station where someone was filling up their car while smoking? I have, several times. Never seen anyone blow up though, depsite all the written warnings and signs everywhere. However, just because I have not seen someone blow up does not mean it is a good idea. The potential is there and it is real - however small the chances, and even though no one on this board has ever sen it.

Just my thoughts. Still, do whatever you feel comfortable with. It is your boat, your system, your life, and your money.

- CD
__________________
Mainsheet Technical Editor, C400
Cruisingdad is offline   Reply With Quote
Old 14-06-2007, 17:16   #23
Senior Cruiser
 
JusDreaming's Avatar

Cruisers Forum Supporter

Join Date: Jul 2004
Location: Stuart, FL & Bahamas Cruising
Boat: Lagoon 37
Posts: 880
Images: 13
we took a direct hit on July 26 of last year. No dyna plate on the boat. But it fried everything. Including my wife's spinal chord stimulator (like a pace maker). She had her foot on the compression post. It blew the water out of the batteries,it fried a laptop that was sitting on the table connected to nothing. It blew the antennas off the top of the mast. You name it and it zapped it! I was happy for marlon thru hulls, as no hull damage happened! And I too am surprised that there is not much interest!!!!!!!!!
__________________
Denny and Diane
Lagoon 37
http://www.svjusdreaming.bravehost.com/
http://www.sailblogs.com/member/svjusdreaming/
"The only way to get a good crew is to marry one." -Eric Hiscock
JusDreaming is offline   Reply With Quote
Old 14-06-2007, 18:02   #24
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Quote:
And I too am surprised that there is not much interest!
The topic comes up on a regular basis but it's a topic that while there is interest there are few answers. Since you were aboard and saw the events you describe, your interest is highly motivated, but it's not very common in the sense that everyone has had it happen or knows someone that has had it happen to.

I have more lightning stories that are land based and they offer little in explaining lightning any more than lightning on the water explains lightning in general either.

The stories about blown through hulls are very rare but very possible. With enough power anything is possible. I would not assume Marlon through hulls are less prone. When you consider that the ability for a spark to jump across a gap is proportional to the power it becomes moot to assume a lightning bolt that came from the clouds could not go any place inside any boat of any proportion. In this sense there is little you can do to assure a solution to the potential lightning problems any more than you can know the weather with 100% certainty. I think your ability to predict weather is far far better than lightning and I don't think weather prediction is anything that great.

I think the "lack of interest" is more a matter of there are great risks associated with sailing the sea and dwelling on them would be to invite disaster. I don't personally see it that way but many do.

With Cruisers Forum you get what you get and you can have a refund if you like. We are only what members decide to make of it. We only have 83,000 members and they all don't show up on a regular basis. It might be a good thing too .
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 14-06-2007, 18:55   #25
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
"The ability to protect a metal envelope as in an aircraft is easy. The ability to protect a boat that is on the strikes path to ground is very different."

Trust me protecting an aircraft and 400 occupants is not easy or taken lightly. The lightning still follows the same laws of phyisics and is still looking for a path to ground. The extensive use of composites in aircraft have made them very similar to boats in terms of the problems associated with protection

The heat, dielectric effects, RF etc. all occur in aircraft as well with arguably a lot more sophisticated and sensitive electronics.

Bonding oll the equipment and providing a low resistance high capacity path to ground is still the key to surviving lightning strikes.

In casual observation I see a three pathologies.

1 - Lighting is a vixen that can't be predicted. The chance of getting hit are so remote you are better of just hoping for the best.

2 - The mast is stepped to the keel so that oughta do it.

3 - Every piece of conductive metal is bonded to every other piece of conductive metal with large copper wire and the is all bonded to a plate on the hull.

I'm not trying to be argumentative at all but if one is serious about avoiding damage caused by lightning strikes step one is a complete bonding system.

Here's an interesting discussion about creating a Farraday cage as a system of protection. This seems pretty intuitive.

Marine Lightning Protection Inc.
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 14-06-2007, 19:26   #26
Senior Cruiser
 
44'cruisingcat's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 7,452
Images: 69
But the aircraft isn't the path to ground. not if it's flying anyway. A boat is actually part of the path to ground when it gets struck. Effectively the boat is PART of the ground.
__________________
44'cruisingcat is offline   Reply With Quote
Old 14-06-2007, 20:42   #27
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
"But the aircraft isn't the path to ground. "

Beg to differ - Anything in the way of the lightnings path to ground is part of the path to ground.

This is a screen shot from a video capture.
Attached Thumbnails
Click image for larger version

Name:	Strike.jpg
Views:	140
Size:	48.5 KB
ID:	1332  
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 14-06-2007, 21:19   #28
Registered User
 
Viking Sailor's Avatar

Join Date: Nov 2006
Location: San Francisco Bay
Boat: Fantasia 35 - s/v Feeling Good
Posts: 1,074
Quote:
Originally Posted by Pblais
I have one and have not been struck. My neighbor with a bottle brush has been hit twice (both times in the slip a few boats down from me).
Interesting! Do you know if your neighbor had a Dynoplate.

Quote:
Originally Posted by Pblais
If you are looking for evidence that having a dynoplate is dangerous then I'm convinced you'll not find that either. I'm sure the dynoplate manufactures could not cover up that fact.
I spent about half a hour trying to find out who makes Dynoplates. It turns out that it is Marinco under the brand name of Guest. Follows is a list of their product features:

Use with SSB radio
Improves performance of electronics and reduces RF interference
Offers the best path for hull bonding without long runs of copper foil
Equivalent to 100 square feet of copper foil
Provides a direct, low resistance path for improved lighting protection
Deters electrolysis and galvanic corrosion
Sintered porous bronze sphere construction for maximum conductivity in a compact size
Low drag, non fouling shape
Easy to install
Conforms to ABYC standards
Easy to clean w/wire brush

You would think that they wouldn't put in a lightning protection feature if they were getting reports of Dynoplates exploding.

Quote:
Originally Posted by Pblais
I'm sorry you were unable to find the answers to your lightning questions here but there are not many answers any place I've ever been either. Some things are not well understood.
Thank you! Sometimes the best way to understand something is to ask a few simple questions.

Quote:
Originally Posted by Curisingdad
Given the very small number of boats with plates that are grounded and have been hit.....
I've had my Dynoplate for 20 years. I have the impression that Marinco sells a lot of Dynoplates per year. If you figure between 4 and 10 boats hit per year I'm not so sure these numbers are that small.

Quote:
Originally Posted by Pblais
With Cruisers Forum you get what you get and you can have a refund if you like. We are only what members decide to make of it. We only have 83,000 members and they all don't show up on a regular basis. It might be a good thing too .
I'd settle for 1%.
__________________
Viking Sailor is offline   Reply With Quote
Old 14-06-2007, 22:21   #29
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
Viking, doing a search may also help. This subject has been very popular in the past. There is a lot of information in the archives.

Ex-Calif, I am not being argumentitive either. But firstly, the aircraft is a large surface area of conductive metal. Boats, except for steel, are not. I have also heard of aircraft that have crahsed due to lightening strike, so aircraft aren't totaly bulletproof....I mean lightening proof either.
It has also been proven that the "cone of protection" idea on boats does not work. it's simple maths and Ohms law. You are trying to conduct a few million Volts and amps to somewhere. Even the slightest resistance in it's path sets up a potential difference of hundreds of thousands of Amps and Volts. The only way you can conduct ALL that current to earth is via a sufficient size super conductor. Something that is still not a reality in the realm of boat masts.
Then there is the electromagnetic field generated. This sets up EMF's in anything conductive. It doesn't have to be in the main currents conductive path. If it is electronic, it is toast, even unplugged. The only safe place is inside a very good farady cage. The best place on a boat is inside the gas oven. Although that even has it's limitations.
The only total effective way of protection is stay away from thunderstorms.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 14-06-2007, 22:36   #30
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
"But firstly, the aircraft is a large surface area of conductive metal. "

Once again, many aircraft are not metal. In fact the 787 and the A350 will be almost entirely "plastic."

"I have also heard of aircraft that have crahsed due to lightening strike, "

I did a quick search of the NTSB database and from 1999 on there are no records af any commercial aircraft losses frm lightning strikes. Lot's of lightning strikes reported with temporary loss of control in some cases but no aircraft losses or fatalities.

All of your discussion about EMF, circuit resistance and transmission of the current is exactly the same in an airplane.

In the interest of not diverting the discussion from the Dynoplate topic any more I will rest.
__________________

__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Reply

Tags
lightning

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
420: Lagoon 420 Owners & Fans ess105 Lagoon Catamarans 1173 21-11-2017 14:36
Lightning and Sailboat unbusted67 Health, Safety & Related Gear 3 04-06-2007 01:45
Choosing Cct Protection GordMay Electrical: Batteries, Generators & Solar 2 01-06-2006 16:57
Lightning Protection Stede Electrical: Batteries, Generators & Solar 5 20-11-2003 18:27
SELECTING LIGHTNING ARRESTORS for SHORE POWER GordMay Electrical: Batteries, Generators & Solar 0 20-09-2003 04:51



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:20.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.