lightening protection

[emnick]

Has anybody fitted any lightening protection? I have the boat out and was contemplating fitting a ground plane for a future SSB installation and to gtound the Navtex I have bought. I then thought I could kill 2 birds with one stone and do the lightening thing as well any body done it? can the ally mast act as a conductor from top to bottom, any body struck by lightening and can you claim for damage done? Thanks all Happy new Year to everybody PS I dont even know where to buy one or how they fit I guess you have to drill through the hull!!??

 

[sarabande]

A technical page I saved some time ago. flash bang wallop

 

[Gin]

I've got lightening protection, courtesy of the season's provenance. I'm now half a stone heavier!!! /forums/images/graemlins/laugh.gif

 

[PhilipH]

You can fit a brush type conductor at the top of the mast and higher than all other aerials, then a copper strip down the mast and over the side of the boat. Alternatively you can put a handheld gps and vhf into a biscuit tin.

 

[PaulJS]

Only seen forked lightning twice in the UK, last time when I was first learning to sail on a loch in SW Scotland.
I made the fastest improvement ever seen in sailing skills, and was alongside, tied up, and as far away from the dinghy as I could get in a time that even impressed my 19 year old instructor!

 

[billcowan]

In case of lightning:

1) put all your electronic toys in the oven, yes it works and yes it is necessary - even if you are not struck, the strong electromagnetic fields from close strikes can upset some toys.

2) lightning conductor - a waste if time, if your hit - chances less than winning the lottery - your mast and stuff will be fried whether or not you have a conductor.

 

[oldharry]

[ QUOTE ]
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2) lightning conductor - a waste if time, if your hit - chances less than winning the lottery - your mast and stuff will be fried whether or not you have a conductor.

[/ QUOTE ]

A somewhat pessismistic view IMHO. Much depends on the strength of the lightning bolt.

Firstly a 'Lightning Conductor' as fitted to high buildings is just that, and is the last thing you want on the boat. It is intended to attract the lightning to itself, and provide an easy route to earth, to prevent lightning passing through other parts of the structure, damaging it.

You really dont want something that ATTRACTS lightning to your boat - unless you have exceptional insurance!

A minor strike on a boat may fry electrics etc, but the boat will often survive intact. Not unusually it blows transducers out of the hull causing the boat to sink, but not always.

A heftier bolt can simply blast through the hull destroying it, or setting fire to it, and there aint much you can do about that!

Lightning PROTECTION is a different game from 'lightning conductors', and is something about which a lot has been written - not all of backed by scientific accuracy. A lot of money is made from kit which claims to protect against lightning, particularly in the US, but which on test appears worthless!

Basically you need to avoid having any sharp pointed things at your masthead, like aerials. In the milliseconds before a lightning strike, a leader descends from the cloud, and any sharp shaped objects in the vicinity will form ground leaders reaching up to make contact with the descending leader. When one of the leaders meets, the connection is made and the heavy main discharges take place through the track created. This is obviously an oversimplification of the process, but shows the need to have the masthead set up to try to prevent the ground leader from forming in the first place.

They normally form only on pointed shapes, so having everything rounded off or flat - a ball on the end of a masthead aerial for example, will go a long way towards preventing leader formation.