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Ok....if I am anchored and its a lighting / thunder storm....see where I am going with this? What happens if the mast is hit by lighting? More important....what happens if I'm on the boat when it gets hit?

Never heard of a Mac being hit by lightning, but a guy on this board had his boat burn up cause of an electrical problem.
Q1

There are a few threads on lightning - if you do a search on lightning and ground you should get enough reading - and they appear divided on the need or usefulness of grounding the mast. If you are not next to the mast/compression post and it is an X when the lightning runs down the compression post and blows a hole in your hull, you will probably be OK - shook up but OK enough to bail, if your on a M I don't know - it might jump to the lifelines and then down the anchor line or down the dagger board.
They (who ever that is) say being close to a lightning strike is similar to being close to an explosion, except you will feel a tingling sensation just before the discharge occurs. Then you will be assaulted with the blast as the superheated air expands and the shock as it implodes (the cause of thunder) and your muscles will contract, the adrenalin level will surge, the heart may pause then race, and finally the brain will process everything. There may have been an involuntary release of your bladder. You could have burns from superheated jewelry, secondary injuries from fails or impacts with other objects and there is usually damage to the eyes. While it is rare - soldiers have been caught out in the open and experienced "ground bounce" or secondary shock and had weapons discharge causing "friendly fire" wounds. Your flares could react in the same fashion.
I would recommend that you consider avoiding lightning strikes unless you are from OZ - for them it is probably no more dangerous than their croc and shark infested waters, snakes and spiders hanging from the tree branches, and other nasties.

yeh tangent,give me lightning over them creepy crawlies in OZ.

im an x i would sleep in the aft compartment during a lightning storm,and hope for the best.

hmmm.....ok, gee, I feel much better - So to recap, I'll either:

1.) feel tingly
2.) become a rotisserie sailer
3.) try and regain conciousness as my mac sinks to the bottom
4.) Feel like I've been hit by a taser
5.) Or feel like a B-29 has just dropped fat man and little boy on me

I think I'll just stay home and drink wine

Corkscrew

Wimp! Prolly french wine too!

We have a set of 20 foot marine jumper cables.

If we get in an electical storm, we plan to attach one end to the shroads and throw the other end overboard, cuddle up in the cockpit and watch the fireworks.

@ tangentair
Our OZ creepy crawlies ain't got nothing on the lightning I saw during a visit to Iowa a few years back. Man, that was SCARY

But we do have thunderstorms in OZ every once in a while, and my Perth Hills residence seems to be located on a good conductor area, I can assure you that lightning DOES strike twice in the same place... like my front driveway.

corkscrew: Take your own advice. If lightning is forecast then stay home and drink wine. Wine might strike the next morning but although it might feel bad, I doubt that it will be quite as severe as the tingling and other effects tang described from a lightning strike.

And if you get caught at anchor in a thunderstorm, then take more of the same same advice... crawl into the aft bunks and drink more wine

Wind Chime wrote:We have a set of 20 foot marine jumper cables.

If we get in an electical storm, we plan to attach one end to the shroads and throw the other end overboard, cuddle up in the cockpit and watch the fireworks.

I've read tons of stuff about this. Most of it conflicting and complicated. What I do remember was that grounding with jumper cables was basically useless.

Interesting link.
Lightning and the Trailer Sailor, To ground or not?

It's an interesting and highly debated topic.

On the Mac, I've come to the conclusion that it's best to stay away from the mast, don't sit under it and don't touch anything metal, then pray. Good news is that extremely few sailors have been killed by lightning compared to other boaters, so maybe that metal stick provides some kind of protection.

corkscrew,you could use the situation to proove the macs superiority over keel boats,heres what you do

1/in a lighning storm,raft up to the neerest large keel boat

2/ lower your mast

3/laugh when the lightning disitigrates his keel boat

waddya think of that plan guys?

Do I smell and episode of Myth Busters?

corkscrew wrote:Do I smell and episode of Myth Busters?

THAT would be a great show.

I loved the one where they busted the cell phone starting a fire at the gas pump.

The overly technical might find this speculation interesting http://analogengineering.com/lightning/surface.html

Im wondering if anyone who has been in one of those intense lightning storms out at sea have actually seen something similar to what is observed in the lab where ionization in air comes down from above and follows the water surface in radial patterns..

on a previous thread discussing lightning and being hit. The conclusion seemed to be:
1. Ground the mast to the water (which may actually attract lightning)
2. Don't add any additional grounding and try to hide from the lighhtning looking for a grounding point.

Both X and Ms have a partial grounding near the mast. In the X the original design (which I still have) is a cable (ie conductor) running from the centre board to about 2 inches from the mast base at its closest. I am not sure of the M's proximity to the mast but if you truly wanted to groung the mast a simple jumper to the cable would work but probably destroy this cable if hit.

I personally prefer to not ground the mast and try to hide from an electrical hit and just don't be sitting near the compression post (on an X) during an electrical storm.

I do not think any of the existing cables are heavy enough to carry the current/voltage of a lightning hit. They would burn through and the charge would seek alternate pathways. To properly ground a mast you would need at least a 00 (double ought) wire and a large disapation field - big metal plate, in my opinion. If you see it coming and can't get out of the way, lowering the mast - maybe, and getting to shore in a low dry enclosure are probably your best option(s) at least in my opinion.