Bonding masts to keel bolts

[danielefua]

Indeed I was kidding. What I meant was that it is better to try as much as possible to "encourage" the discharge current to go through a controlled path where it makes minimum damage. I believe that letting it find its path freely across the deck or the topsides is not wise.

Daniel

 

[jfkal]

Cool but lightning will not bother to snake along the cable. most of it will simply arc across.

 

[danielefua]

You are right but what worries me is the indeterminacy in your words "most of it". Most of it may be too much and I would prefer that the most of it is a percentage very, very close to 100. This is possible if the link between mast and keel bolt is very good and maintained so. Including the specs illustrated by Roberto in a previous post.

Daniel

 

[jfkal]

Cable or rod should provide a straight path with as little horizontal travel as possible. what I have done is a collar around the mast a bit higher up and from there a thick cable in a straight line to the next keel bolt.
copper rod would be even better though

 

[Baddox]

Any suggestions as to best online place to buy 3-4m of 50 sq mm cable?

Welding suppliers sell 50mm cable and thicker at good prices. You may want tinned cores for corrosion resistance.

 

[Baddox]

iirc, any lightning conductor is designed to dissipate charge and thus avoid a direct strike, rather than conduct away a full strike. This may redefine the problem and what can be done to avoid it in the first place. Another option is to use anchor chain to conduct charge from the mast, over the side and into the sea.

 

[anoccasionalyachtsman]

I found that the best time to debate all of this was as we raced towards an electric storm off Guernsey. Pretty much an entire crew of engineers. The conclusion was that we should forfeit our possibly race-wining inshore position and edge out to be among the other boats, maybe with taller masts.