Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 17-06-2018, 03:42   #1
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
"G-stud" lightning grounding system.

I know that a good bit of info has been tossed around about lightning protection in general....

Specifically I am curious if anyone has experience with the G-stud promoted by these guys.

www.marinelightning.com

It is a 1/2 inch bronze stud imbedded in a thru-hull fitting. Designed to replace the classic copper sheet or strip.

Any experience with this product?
Is it an effective replacement for the one square foot copper sheet?
Any info out there on performance in an actual lightning strike?

Thanks
__________________

w32honu is offline   Reply With Quote
Old 24-06-2018, 05:14   #2
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 925
Re: "G-stud" lightning grounding system.

Are you referring to the Siedarc conductors in general, or the specific bonding of a saildrive leg?

We have that system bing installed and I have researched it pretty extensively, so are you asking does it work, or what is the principle of why it works?

It certainly is much better than the "edge effect" of the copper plate, not least because it is equalising the voltage field at the sea surface, rather than below the surface.


Sent from my iPad using Cruisers Sailing Forum
__________________

BigBeakie is online now   Reply With Quote
Old 24-06-2018, 06:10   #3
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
Re: "G-stud" lightning grounding system.

Big,

Thanks for the response.....

I was referring more to the "G-stud." The g-stud is promoted as a replacement for the classic copper strip that measures at least one square foot. The g-stud is imbedded into a classic thru-hull arrangement and would provide a much cleaner installation. It is designed to be installed below the water line.

From a layman perspective I was curious about a comparison of the two methods and the effectiveness of the G-stud. The older method of a copper plate is deemed to be effective because of the linear surface of the edge of the plate. The stud does not provide that edge. It is simply a 1/2 inch solid bronze stud imbedded in the thru-hull.

You seem to imply that the g-stud works in tandem with the siedarc. Is that what you are saying? The Siedarc is designed to be installed just at the waterline or slightly above.

Originally this company sold and marketed a "plate" or "strip" for grounding. They replaced it with the "G-stud."

In any case, I am glad to correspond with someone who is installing their system...

The big question is; Do we know of anyone who has this system installed and has been struck by lightning? And then what were the results?

Thanks,

S
w32honu is offline   Reply With Quote
Old 24-06-2018, 06:21   #4
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
Re: "G-stud" lightning grounding system.

On their website.......

Marine Lightning Protection Inc.

Go to "Products."

Go to "Grounding Strips."

The G-stud is now there instead of the grounding strip. They no longer recommend a grounding strip, but instead the g-stud.

Snake oil or gimmick? All seems legitimate to me. Well documented science...etc.

Curious about real world applications and results.
w32honu is offline   Reply With Quote
Old 24-06-2018, 18:32   #5
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 14,575
Re: "G-stud" lightning grounding system.

There was some research published maybe three years ago, indicating that the real lightning problem was because an ionic charge built up in the moist air that sits just above the waterline. Not a ground charge in the water, but a surface charge sitting above the water. And the logic was then that "grounding" a boat into the water, is the wrong way to do things because it bypasses the active surface charge that is sitting in the moist air.

Their logic was that by installing "ground stubs" perhaps six inches above the waterline, and running the ground system into those, you would allow the static discharge to/from the actual area where the charge was strongest: In the moist air, not in the water.

So it sounds like these guys are pushing the same concept, putting ground "stubs" in the hulls in the area of the highly charged moist air, rather than into the water.

AFAIK no one has published confirmation or refutation of the concept, either way.
hellosailor is offline   Reply With Quote
Old 30-06-2018, 06:25   #6
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 925
Re: "G-stud" lightning grounding system.

Here is my understandings from speaking with and correspondence with Dr. Thomson.

The edge effect of a conducting plate underwater is mainly at the points of the corners, so it is as effective or more effective, to have one point and a bigger one at that, hence the through hull conductor. The principle is to give the electrical voltage field the easiest path to ground, as we've all heard. I believe the evidence is partially based on voltage discharge experiments with high speed photography. I am not sure of the references for this.

As Hellosailor has outlined, the same high speed photography/film also shows lightning discharges at the surface film where the charges balance, in milliseconds. The Siedarcs are therefore placed as close to the waterline as possible.

It's a bit easier to locate the bridgedeck conductor as it is adjustable, so we will lower it to the sea surface when at anchor, in case a thunderstorm comes during the night.

The specs of how to implement the system are part of Dr. Thomsons service so it has the highest effectiveness.

As far as effectiveness, I spoke to a cruiser in North Carolina who was struck, he believes, on his cat while at anchor in Florida with no damage to any equipment, but it's my only user data point. Still, since cats are struck about twice as often as monos and suffer on average much more damage, (US Boating Association study) I think it's as good a preventative measure as there is, so we're going with it during our build. Its easier to run the cables when there is good access rather than after all furniture and interiors have been installed.


Sent from my iPad using Cruisers Sailing Forum
BigBeakie is online now   Reply With Quote
Old 30-06-2018, 06:50   #7
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
Re: "G-stud" lightning grounding system.

Big,

Thanks............very much appreciated.

We are also in the process of building. A cruising trimaran in our case. This question of lightning protection is important, I believe.

I think that a consult with Doc Thomson might be worthwhile. Last correspondence I had with him.......he suggested that the "G-stud" was used mainly to bypass any transducers because they tend to blow out as a result of a strike. Definitely a bad outcome. He recommended grounding to a strut and or shaft as the main connection. And this might make good sense in our case as the shaft is isolated from the engine. And the strut and shaft have the most protection from galvanic corrosion.

So in our case I am considering a "G-stud" forward which would directly ground the aluminum mast. In addition ground the back stay to the strut and shaft. The other stays and shrouds would be good candidates for the "Siedarc." So maybe six or eight of the Siedarcs located out on the Amas.

Thanks again for the input.

S.
w32honu is offline   Reply With Quote
Old 30-06-2018, 11:21   #8
Registered User

Join Date: Jan 2011
Location: BC Canada
Boat: Marples 37
Posts: 122
Re: "G-stud" lightning grounding system.

Quote:
Originally Posted by w32honu View Post

So in our case I am considering a "G-stud" forward which would directly ground the aluminum mast. In addition ground the back stay to the strut and shaft. The other stays and shrouds would be good candidates for the "Siedarc." So maybe six or eight of the Siedarcs located out on the Amas.

S.

Just noticed your building a larger version of our boat. One thing I've often thought about is that the external chainplates on our amas stop approx a foot above the waterline. Would there be any benefit in having them go below the waterline in a lightning strike.
CGirvan is offline   Reply With Quote
Old 30-06-2018, 15:39   #9
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
Re: "G-stud" lightning grounding system.

Quote:
Originally Posted by CGirvan View Post
Just noticed your building a larger version of our boat. One thing I've often thought about is that the external chainplates on our amas stop approx a foot above the waterline. Would there be any benefit in having them go below the waterline in a lightning strike.
C,

Thats a good point. But I might hesitate. We have made every attempt to build this boat exactly as John designed it. Besides Stainless Steel does not like to be submerged underwater.

The chain plates are through bolted.......so we were going to pick up one of the bolts inside the Ama and run a lead off of that to a Siedarc fitting. The Siedarc is installed just above the water line.

BTW we love the CC-37 design. That is what inspired our boat. It is that same boat scaled up and used the structure and molds for the CC-40 but with the FC interior. So it falls right in between the 37 and the 44 FC with wing pods. I think they are fine cruising boats.

All the best,

Cheers,

S
w32honu is offline   Reply With Quote
Old 01-07-2018, 04:29   #10
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 925
Re: "G-stud" lightning grounding system.

W32,

That sounds like a pretty good plan. Your main challenge will be persuading the lightning hit to divert from the base of the mast to the sea surface by taking a right angle turn at the mast bulkhead. A wide turn radius of the down conductor would be preferable, there are specs for that from the power line industry. High voltages do not conduct well around sharp corners, that is my uneducated understanding. Check that aspect with Ewen Thomson.

I am considering using large aluminium cable as used in power transmission lines for our mast down conductor under the bridgedeck. You can get it from scrap metal dealers at much more attractive pricing than large copper cable. That is for getting as much surface area on the cable as practical.


Sent from my iPad using Cruisers Sailing Forum
BigBeakie is online now   Reply With Quote
Old 01-07-2018, 07:33   #11
Registered User
 
w32honu's Avatar

Join Date: Dec 2009
Location: New Hampshire
Boat: Custom Marples 40 FC
Posts: 480
Images: 2
Re: "G-stud" lightning grounding system.

Quote:
Originally Posted by BigBeakie View Post
W32,

That sounds like a pretty good plan. Your main challenge will be persuading the lightning hit to divert from the base of the mast to the sea surface by taking a right angle turn at the mast bulkhead. A wide turn radius of the down conductor would be preferable, there are specs for that from the power line industry. High voltages do not conduct well around sharp corners, that is my uneducated understanding. Check that aspect with Ewen Thomson.

Sent from my iPad using Cruisers Sailing Forum
Thanks Big,

Thats a good point....

We were going run a 4AWG lead from the base of the mast. Our mast is deck stepped and because we are a tri, we were going to run the lead straight down to a "G-stud." So any bends would be very minimal. The "G-stud" would be just below the water line..........maybe 9 to 12 inches.

Then we were thinking of grounding the back stay chain plates to the strut and prop shaft. They will have galvanic protection with zincs.....etc.

The rest of the rig (shrouds and Forestays) we were thinking of grounding to "Siedarcs" and installing those just above the water line as Doc Thomson recommends.

So that is the rough plan. As you mentioned, I think it is a good idea to have a consultation with Doc Thomson. That way we have a better chance of getting it right and protecting the boat.

Although there are no guarantees when dealing with lightning. A bit of research and thoughtful planning combined with a bucket of good luck should give us a piece of mind.

One question....... Are you installing a "lightning rod" at the masthead? Or are you going to let the mast stand on its own with no rod?

Thanks,

S
w32honu is offline   Reply With Quote
Old 21-07-2018, 05:35   #12
Registered User

Join Date: Jan 2014
Location: Sydney, NSW
Boat: FreeFlow 50 cat
Posts: 925
Re: "G-stud" lightning grounding system.

Sorry for delay W32,

Yes, have made up threaded 6061 alloy rod that is the highest point on masthead. Everything else falls within the 45 degree cone from the rod tip. We hope that will offer some protection for the VHF/AIS antenna up there, but no guarantees on that one, the induced current may be overwhelming depending on the strength of the lightning bolt.

Also the shape of the lightning rod tip is another bit of IP from Dr. Thomson.


Sent from my iPad using Cruisers Sailing Forum
__________________

BigBeakie is online now   Reply With Quote
Reply

Tags
lightning

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
[SOLD] 8mm - 5/16" Navtec Norsman stud fitting ejlindahl Classifieds Archive 5 12-02-2016 10:43
DC Negative Grounding to grounding plate - Isolated shaft Thistle1969 Electrical: Batteries, Generators & Solar 17 27-09-2015 05:51
Grounding For A Lightning Strike endoftheroad Construction, Maintenance & Refit 1 05-01-2014 06:00
Grounding Against Lightning Strikes kb79 Marine Electronics 7 20-01-2010 22:30



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:55.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.