Use a metal swing keel for lightning sink - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest > General Discussion (sailing related)
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #1  
Old 01-22-2013
Member
 
Join Date: Sep 2012
Location: Michigan
Posts: 76
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 2
mustangchef is on a distinguished road
Use a metal swing keel for lightning sink

I actually have a Lightning and wonder if i can wire the aluminum mast to the swing keel for lightning protection?
Reply With Quote Share with Facebook
  #2  
Old 01-22-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,836
Thanks: 28
Thanked 54 Times in 50 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Use a metal swing keel for lightning sink

You are better off putting a bronze plate or dynaplate I think. Read this thread. Mainesail has one type of setup. I have a Newmar ground shoe

lightning advice
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
  #3  
Old 01-22-2013
RichH's Avatar
Senior Member
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 2,760
Thanks: 9
Thanked 64 Times in 57 Posts
Rep Power: 15
RichH will become famous soon enough
Re: Use a metal swing keel for lightning sink

There's been recent suggestions from research that the 'sink/ground' for lightning shouldn't be deep 'underwater' but rather at the water surface. Some are advocating 'waterline' dissipators and electrodes: Marine Lightning Protection Inc.

Noone really knows, Ive been 'hit' three times on different boats ... it all remains a 'crap shoot'.
Reply With Quote Share with Facebook
  #4  
Old 01-22-2013
mad_machine's Avatar
Sea Sprite 23 #110 (20)
 
Join Date: Dec 2012
Location: Atlantic City, NJ
Posts: 3,107
Thanks: 5
Thanked 62 Times in 53 Posts
Rep Power: 2
mad_machine is on a distinguished road
Re: Use a metal swing keel for lightning sink

Quote:
Originally Posted by RichH View Post
Noone really knows, Ive been 'hit' three times on different boats ... it all remains a 'crap shoot'.
I think emphasis on Crap.... because I know something like that would scare it out of me.
__________________
Art Haberland
__________________

In the end all that matters is how fully you loved, how gently you lived, and how gracefully you let go of things that did not belong to you -buddha
Reply With Quote Share with Facebook
  #5  
Old 01-22-2013
Senior Member
 
Join Date: Jan 2011
Posts: 666
Thanks: 0
Thanked 17 Times in 17 Posts
Rep Power: 4
Frogwatch is on a distinguished road
Re: Use a metal swing keel for lightning sink

Dynaplates and "Grounding shoes" WILL NOT WORK AS LIGHTNING GROUNDS.

The reason, Remember basic Electricity and Magnetism in physics? The electric field within a closed conductor is zero. This means that at high values of E field (Lightning), the field simply bridges the pores of the plate giving only the external area to dissipate the current.
At low values of E (low current typical of radios etc), the field does NOT bridge the pores so it acts as if it has a huge surface area.

For a lightning dissipating ground, you really do want a large external area and as much "external" edge as possible. The field is highest at the edge and that is where the current will go.

Yesterday, somebody posted a pic of what I think is a good lightning ground, it was a narrow long strip on their outside hull. However, it looked as if it was painted. Be careful, some anti-fouling paints do not conduct and you want it to readily conduct

So, as long as you keep your metal centerboard painted with CONDUCTING paint, it'll work cuz it has lots of surface area. I'd worry about using the CB pin as your contact though.

The reason for wanting your lightning ground close to the surface is for two reasons and I am not sure they make sense :

1. Analogy to the E field within a conductor (Yeah seawater is a good conductor for most low frequencies) says the field there should be zero so it seems like no current would flow. Not true, remember that in a VAn de Graff generator the charge is brought to the INSIDE of the big hollow HV terminal and then it simply goes to the surface. I do not think this reason makes sense.

2. High frequency "skin effect" whereby high freq components of the lightning pulse travel best on the surfaces of conductors. Maybe, maybe, maybe.

My lightning ground on my sailboat (up till now) was a 2' X 2' copper sheet (flashing) with a copper bolt/clamp/soldered to a tinned #00 insulated Ancor cable 15' long with a good welders clamp to attach as high as I can on the mast to avoid bends of the wire. During a storm, the plate gets dropped overboard and the clamp goes on the mast. A Nylon rope keeps the plate from being dragged backwards to ward the prop and I maintain only steerage speed. Yes, I am paranoid of lightning.
Reply With Quote Share with Facebook
  #6  
Old 01-22-2013
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,453
Thanks: 1
Thanked 77 Times in 75 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Re: Use a metal swing keel for lightning sink

A Dynaplate as a lightning ground is outright dangerous, and they're the first ones who'll tell you so. Dynaplate is made from sintered bronze in order to provide greater contact area (much much greater) than a simple plate. If it takes a strike, all the water that is filling the voids in the sintered metal instantly flashes over into superheated steam, producing an explosion.

Not a good thing.

So by all means, a solid plate would beat nothing. Using the swing keel probably is better than nothing (or a Dynaplate (G)) but how effective it would be would depend on whether you could make a fairly straight cable run or not, and how much resistance was in the swing pivot.

Of course with a boat that small you always have the option of the best lightning protection in the world: Invert the boat and come back after the storm.
Reply With Quote Share with Facebook
  #7  
Old 01-22-2013
paulk's Avatar
Senior Member
 
Join Date: Jun 2000
Location: CT/ Long Island Sound
Posts: 2,533
Thanks: 4
Thanked 20 Times in 19 Posts
Rep Power: 15
paulk is on a distinguished road
Re: Use a metal swing keel for lightning sink

For a Lightning, the best thing might be to simply drape a conductor (jumper cables?? a chain??) from the upper shrouds into the water when you're moored. Mooring next to a boat with a taller mast might work too. You aren't likely to purposely head out into thunderstorms, so you probably don't need anything set up when you're sailing the boat. You certainly could re-rig your conductor if a storm came up while you were out; it's just a good bit of drag otherwise. I've been out in Lightnings in some nasty thundersqualls. Taking down the sails and moving aft in the cockpit (away from the rigging and centerboard) seemed to work well enough. As mentioned above, for a grounding plate you want as much surface exposed to the water as possible. This would indicate having the centerboard down all the way. Leaving the centerboard down on a moored Lightning is a sure-fire way to capsize it at the mooring: I have seen it happen at Larchmont Race Week. A squall comes through with a new wind direction, and because the board is down, the boat can't swing fast enough to head into it. The gusts hit the boat and mast broadside, the board keeps the boat from turning, and with no ballast (crew) to counter it, the windage knocks the boat over. Friends of ours have been hit by lightning, but they were on bigger keelboats.
Reply With Quote Share with Facebook
  #8  
Old 01-23-2013
mad_machine's Avatar
Sea Sprite 23 #110 (20)
 
Join Date: Dec 2012
Location: Atlantic City, NJ
Posts: 3,107
Thanks: 5
Thanked 62 Times in 53 Posts
Rep Power: 2
mad_machine is on a distinguished road
Re: Use a metal swing keel for lightning sink

Quote:
Originally Posted by Frogwatch View Post
My lightning ground on my sailboat (up till now) was a 2' X 2' copper sheet (flashing) with a copper bolt/clamp/soldered to a tinned #00 insulated Ancor cable 15' long with a good welders clamp to attach as high as I can on the mast to avoid bends of the wire. During a storm, the plate gets dropped overboard and the clamp goes on the mast. A Nylon rope keeps the plate from being dragged backwards to ward the prop and I maintain only steerage speed. Yes, I am paranoid of lightning.
Have you ever considered a "trolling plane" (for lack of a better word) when I was younger, friends used to take their boats out fishing. They always had these two stainless steel "planes" that had hooks attached to them. They would toss them overboard the stern and the speed of the boat would pull them straight down.. untill a fish grabbed a hook and then it would allow the rope attached to it to slide forwards and they would ascend.

I think something similar would work for you.. just make it so it cannot ascend on it's own and unless you want fried fish for dinner, do not put hooks on it
__________________
Art Haberland
__________________

In the end all that matters is how fully you loved, how gently you lived, and how gracefully you let go of things that did not belong to you -buddha
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Swing Keel or Fixed Wing Keel? Catalina 22 or 25? BRCincy Boat Review and Purchase Forum 56 3 Days Ago 09:08 AM
Seafarer 24 swing keel, keel pivot? Sailing qualities? skygazer Boat Review and Purchase Forum 44 10-21-2013 09:50 PM
to Swing or Not to Swing ... keel that is nogin General Discussion (sailing related) 30 04-22-2010 09:57 AM
Swing Keel or Fixed Keel for Caribbean Sailing SailorJim123 Boat Review and Purchase Forum 1 02-04-2009 10:15 AM
Drop keel from wood to metal?? caskin Sailboat Design and Construction 10 07-10-2008 10:35 AM


All times are GMT -4. The time now is 04:04 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.