SailNet Community - Reply to Topic

   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 > Skills and Seamanship > Seamanship & Navigation > Lightning Strike??
 Not a Member? 

Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


Thread: Lightning Strike?? Reply to Thread
Title:
  

By choosing to post the reply below you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Topic Review (Newest First)
08-19-2010 10:01 AM
smurphny
Grounding of metal parts

It is certainly intimidating when a thunderstorm starts to head your way. Once looked up for a weird sound aboard my commercial fishing boat and watched as an antenna started to "sizzle" as a storm approached . Other than that instance (got the H out of there fast), have never had a run-in with a bolt of lightning although through many storms over the years. It seems to me that being hit is probably as random an event as it is on land. I guess the theory is to make your boat's potential the same as the sea by grounding it to the water, giving the electricity no reason to be attracted to your spot. I do not understand this at all because the boat is above the surface of the water and would seem, logically, to be a target just BECAUSE it is connected to the water and hence a higher strike point way up there at the masthead. One thing I do when a storm is coming is to completely detach my electronics from antennas/batteries/grounding...everything. This way if I do get hit, at least I may still have some communication capability. It also saves a lot of expensive gear from melting down all at once which has happened to more than one sailor I know.
08-16-2010 07:15 PM
rebelheart If you have a wooden spar, a direct hit down the mast will generally cause the mast to split / explode as the water is superheated and expands with the heat. You can rig a temporary lightening rod, or put a permanent rod up that connects to the main track, then run a thick cable from the track to something metal in the water that you're okay with passing a ton of current through.
08-02-2010 11:56 PM
Saltee In his book Sailboat Electrics Simplified, Don Casey has a succinct write up about boats and lightning. Included is a good discussion on proper bonding techniques (separate the lightning and electrical system grounds, easier said than done). Stray currents damage electronics if the grounds are tied together. It’s like arc, MIG, or TIG welding on a steel hulled vessel without disconnecting the electronics.

I’ve worked on a few antenna installations on buildings with coax isolators installed. One installation worked great, a crispy black antenna with no other damage. The other installation wasn’t so lucky, blown out TV, computer, etc. A lot of the randomness is likely due to directness of path, quality of connections, corrosion at terminals, size of conductors, etc.

Even if a boat is grounded properly, I think it would be more at danger on dry land. I’ve seen photos of boats in boatyards that had holes blown in the bottom of the hull because the lightning was desperately trying to get to ground. In the same vein as dragging a chain through lakes, if the boat will be stored on the hard it’d make sense to ensure a direct path to ground with a chain, cable, or wire.
08-01-2010 10:21 PM
TQA
Quote:
Originally Posted by Jeff_H View Post
Actually, almost nothing is more scary to me than to be on a steel boat in a lightning storm. A lightning strike on a steel boat is especially dangerous. The large voltage through the steel can literally electric arc cut the plating and can instanteously eletrolysize away sections of the hull. I looked a steel boat that had was being salvaged in South Florida years ago and a large chunk of the bottom plating looked like swiss cheese. The owner was badly burned and one of the crew was left in critical condition after receiving a major shock thought to be from induced current through a portion of the hull.

Jeff
web page: http://www.cdc.gov/nasd/docs/d000001...7/d000007.html
or pdf file: http://www.cdc.gov/nasd/docs/d000001...07/d000007.pdf

[Note these are EXCERPTS ONLY. And there's also info on electronics.]

Quote:
LIGHTNING-PROTECTED BOATS
There is no such thing as lightning-proof boats, only lightning-protected boats. All-metal ships are rarely damaged, and injuries or deaths are uncommon. These ships are frequently struck, but the high conductivity of the large quantities of metal, with hundreds of square yards of hull in direct contact with the water, causes rapid dissipation of the electrical charge.
I also had an afternoon with a wonderful and very experienced compass adjustor who worked the east coast of the US and his stories seemed to back up my personal experience that if you are going to be struck ,a steel boat with an ali mast was the way to go.

I was inside the cabin and not touching anything metallic when the strike happened. I suspect that had I been on deck the risk of injury would have been higher but again the experts say the lecky will take the path of least resistance soooooo I think the hull gets it and not the crew member.

Oh yeah the adjustor was onboard to drive out the evil spirit [magnetism] that had taken up residence. It looked like Balinese ritual dancing and some Tai Chi as he herded the spirits into corners and drew them off into space. All for a six pack too !
08-01-2010 05:19 PM
Gary M Lightning seems to be totally random. Here on Lake Huron we get a huge number of lighting bolts a year and often while racing have dozens and dozens of boats out in storm. It totally amazes me that more boats do not get hit. I hear of maybe 2-3 per year.
Typically it just fries the electronics. It can be much worse, rarely are there injuries although a few years ago a helmsman was burnt as the bolt transferred down the back stay. Years ago an Alberg 37 was hit and a friend who saw it after they raised it said the hull looked like it had been hit many times by a shot gun blasts.

Stay away from the metal parts and "hope for the best" My view is a well grounded boat is your best defence although I tend to believe you are more likely to get hit in one.

Lighting does not vary very far off it's intended path. One year in a thunder storm I felt a blast of heat and smelled very strong ozone. That is about as close as I want to get to a strike
08-01-2010 04:28 PM
noelex77
Quote:
Originally Posted by Jeff_H View Post
Actually, almost nothing is more scary to me than to be on a steel boat in a lightning storm.
Jeff
There is no guarantees with lightening, but a metal boat is safer than a non conductive material, such as fiberglass.
The metal provides a good ground (which is sometimes added in fiberglass boats with thick wiring to reduce the damage associated with a strike) and the conductive nature of the hull material provides a faraday cage that protects crew below.
08-01-2010 02:54 PM
killarney_sailor We were hit by lightning on the way to Bermuda many years ago. If it makes people better (and perhaps it should) the remarkable thing was not that we were hit but that it took so long to be hit. Bolts were hitting the water around us constantly for 20 minutes or so before we were hit. Damage was not too bad, nav lights blown out, vhf not working, voltage regulator cooked. I saw it hit the windex which blew off. one of the crew was holding the wheel with considerable rainfall in the cockpit and bare feet and felt nothing.

There just seem so many random factors associated with lightning that it is virtually impossible to draw any firm principles for dealing with the subject.
08-01-2010 02:13 PM
chris31519 Don't forget that water - especially fresh water - is not a good conductor. When you earth the mast you have to consider what it's earthed to, it needs to be able to dissipate the current. I sail often in a large shallow lake and drag a chain to the lake bed when a storm comes, (as well as earthing the mast to the iron keel that has a large surface area). There's lots of good info on the Internet.
e.g Lightning Protection on Sailboats
07-29-2010 06:23 PM
Jeff_H Actually, almost nothing is more scary to me than to be on a steel boat in a lightning storm. A lightning strike on a steel boat is especially dangerous. The large voltage through the steel can literally electric arc cut the plating and can instanteously eletrolysize away sections of the hull. I looked a steel boat that had was being salvaged in South Florida years ago and a large chunk of the bottom plating looked like swiss cheese. The owner was badly burned and one of the crew was left in critical condition after receiving a major shock thought to be from induced current through a portion of the hull.

Jeff
07-29-2010 05:07 PM
TQA If it is something that really REALLY worries you buy a steel boat.

The path to "earth" is not interrupted by fibreglass so hull damage is most unlikely. If in side when you are hit you are in what is called a Faraday Cage and if you have to be struck then that is a good place to be. [ You might be deaf for a day or two - ask me how I know this.]

But there is problem that only steel boat boats may suffer from subsequent to a strike, the hull can become a strong magnet and your compasses are useless. Mine pointed to 137 degrees regardless of my actual heading.
This thread has more than 10 replies. Click here to review the whole thread.

 
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


All times are GMT -4. The time now is 06:57 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.