Yachting and Boating World forums: lightning conductor

I tend to feel that Salty Johns dimensiojns are on the light side. I understood more like 3 square ft of metal contact with the sea and the 8 sqmm wire would be too light.

The problem with yachts is the aluminium mast, a very low resistance pole which should conduct a lot of current without damage. It is the remainder of the path from mast to water that needs a large conductor.

Hopefully the grounding cable will dissipate much or all of the current energy before it fuses into molten copper.

Now with a wooden mast if it were dry you might be better off not trying to attract the lightning however with a brass track up the mast you are back to the same as an Al mast.

What happens in a lightning strike is that a leader starts from the ground it is not very powerfull and can function through fairly high resistance (wet tree). This leader provides a conductive ionised path for the main current to come down.
When it meets any resistance the current will produce heat usually fusing the conductor with the fused part providing ionised air and metal to continue the current flow. Hence trees explode when the moisture boils.

The brass track will provide some conductivity and may be comparable in cross sectional area to a decent cable. It would probably be ruined in a strike but that may not matter so much. So I would suggest connecting the brass track to the keel or other in water metal. You may then consider adding another cable down the mast to help carry the current. But then you ask how much is enough? I think I would not add any more cable just hope for the best. If you want you can fit a conductive rod at the top to a point above the mast. I don't think I would.

Don't use stainless stay wires as conductors as the resistance will just fuse them quickly. Galvanised iron wire may be OK lower resistance)
In most boats there are electrics of some sort in or on the mast. This is connected to the sea via negative of engine. All this wiring will smoke unless it is adequately bypassed by a very heavy cable earthing the mast. (And then may still still get smoked)

The whole plan is to minimise damage to the crew and if possible minimise damage to the boat.
Lets hope it never happens olewill

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