Is our mast grounded?

[David M]

If a lightning bolt can arc across miles of sky, it certainly has the ability go wherever it wants to within your boat, grounded mast or not. A grounded mast probably helps but it does not guaranty anything.

[transmitterdan]

Originally Posted by boatpoker

which one is the path of least resistance ?

All of them. By definition.

[noelex 77]

We received a nearby lightning strike while at anchor, causing some damage to instruments, a few years ago. I did a lot of subsequent research on the subject.

My conclusions were:

1. Grounding the mast makes very little difference to the chance of a lightning strike. If anything, contrary to popular opinion, grounding the mast slightly reduces the chance of a strike, although the effect is very small. The reduction is due to the grounding dissipating the static charge that can accumulate at the mast head, particularly as the mast sways back and forth.

2. Grounding reduces the risk of damage if a strike occurs, but in no way guarantees there will no damage. Grounding tends to have little impact on the effects of minor damage (such as damage to electronics), but does have a reasonably protective effect (when correctly installed) to the risk of severe damage (such as when a large hole is blown in the boat and it subsequently sinks).

I think long distance cruising boats should have their mast grounded. The sudden development a big hole will ruin anyone's day, but for the OP there are a lot of systems that would be higher on my priority list when sorting out a recently purchased 28 foot boat.

There is some evidence that grounding both the port and starboard hulls of cats can reduce the risk of strikes to a similar level as a monohull. This is worth some investigation for cat owners.

[Paul L]

Originally Posted by thomm225

I gave you three sources to support my argument.

As you most probably know, most off the so called data out there concerning lightning is very suspect as if the researchers had already made up their minds on the subject and were simply trying to back it up with some thrown together stats.

It's appearing more and more like you just cannot handle being wrong rather than acknowledging the fact that going "unprotected" is possibly a good way to go.

I ........

Nah, what I have stated is that you have not produced any data that indicates that a lightning grounded vs ungrounded mast gets hit more or less. And each of your posts supports that.

[thomm225]

Originally Posted by Paul L

Nah, what I have stated is that you have not produced any data that indicates that a lightning grounded vs ungrounded mast gets hit more or less. And each of your posts supports that.

You can lead a horse to water, but you can't make him drink.

It really doesn't matter what I say or show you because you will continually disagree and use "alternative facts" to back up your opinions.

But, I'll post this one more time and then I'll leave you to your unsupported alternative facts

Examining the Theory

An ungrounded mast will have a finite number of free electrons compared to a grounded mast which is being fed an unlimited supply from the water surface. And while those electrons will be attracted to the upper extremities of the mast by the opposing cloud potential, its not been proven that they could sustain a spark capable of jumping to cloud leaders especially if a single diversion point (air terminal) is not provided as a congregating and launching point. It should be remembered, that air while it is a good dielectric, is not a great one and will allow free electrons to bleed off harmlessly from the mast head unless an air terminal is provided and because of the finite number the ungrounded mast will doubtfully produce an attachment spark. This possibility could be further reduced by avoiding a vhf antenna (good air terminal) at the top of an ungrounded mast and installing an ion diffuser as the upper structure.

When comparing the Florida survey statistics to those provided by Boat US for insurance claims for example, six sailboats with auxiliary power per thousand suffer lightning damage but only two per thousand that are sail only.

[boatpoker]

Originally Posted by thomm225

claims for example, six sailboats with auxiliary power per thousand suffer lightning damage but only two per thousand that are sail only.[/B] [/FONT]

I'm not arguing for either side in this discussion as neither side can provide scientific proof, just a whole load of internet opinion of dubious value.

However, in this BoatUS example how many of those boats that are sail only are dry sailed lasers (or the like) and rarely on the water during lightning storms.

[thomm225]

Originally Posted by boatpoker

I'm not arguing for either side in this discussion as neither side can provide scientific proof, just a whole load of internet opinion of dubious value.

However, in this BoatUS example how many of those boats that are sail only are dry sailed lasers (or the like) and rarely on the water during lightning storms.

Not many these days because folks need their diesel, fridge, AC, power windlass, etc, etc

(But) There are some of us that have always wanted to do it, cruise, the right way..........at least what we perceive to be the right way we have always dreamed of

This goes back to my thinking about the lightning squall I encountered. The following week I thought about my boat and how I'd bolted all the grounds that went to my engine together and returned them to the battery's negative post.

My boat is "floating" electronically which possibly is a good thing in a lightning storm. Here's the storm coming on and I'm maybe 250 yards from shore.

These storms/squalls get your attention and make you think.

I was actually filming this to support an argument on CF that CQR anchors simply thrown overboard without backing down do work if you have a bit of experience and know the bottom, but I didn't have any idea that this squall would be this strong

Thirty minute before the sky looked like the attached photos. The thunder/lightning directly over head in the third video can give you pause. I was thinking at least they will know (my people) what happened if I get hit.

https://www.youtube.com/watch?v=zHt7ocBZKms

https://www.youtube.com/watch?v=okRZs6os5Eo

https://www.youtube.com/watch?v=6gcZKr25UUM

Btw, the following day was quite clear and breezy as I sailed toward the east across the bay: see photo with jib sail only up

[boatpoker]

OMG !
I've heard of drift but turning this into an anchor thread !
Masterful

[thomm225]

Originally Posted by boatpoker

OMG !
I've heard of drift but turning this into an anchor thread !
Masterful

Many folks want a grounded mast because they are worried about lightning during a storm.

Many storms cause the wind to rise a bit.

If the wind rises and you are near shore, anchoring is important

It's not that big of a stretch.

Go out and buy yourself a CQR now before they are all gone!

[Paul L]

Originally Posted by thomm225

You can lead a horse to water, but you can't make him drink.

It really doesn't matter what I say or show you because you will continually disagree and use "alternative facts" to back up your opinions.

But, I'll post this one more time and then I'll leave you to your unsupported alternative facts

Examining the Theory

An ungrounded mast will have a finite number of free electrons compared to a grounded mast which is being fed an unlimited supply from the water surface. And while those electrons will be attracted to the upper extremities of the mast by the opposing cloud potential, its not been proven that they could sustain a spark capable of jumping to cloud leaders especially if a single diversion point (air terminal) is not provided as a congregating and launching point. It should be remembered, that air while it is a good dielectric, is not a great one and will allow free electrons to bleed off harmlessly from the mast head unless an air terminal is provided and because of the finite number the ungrounded mast will doubtfully produce an attachment spark. This possibility could be further reduced by avoiding a vhf antenna (good air terminal) at the top of an ungrounded mast and installing an ion diffuser as the upper structure.

When comparing the Florida survey statistics to those provided by Boat US for insurance claims for example, six sailboats with auxiliary power per thousand suffer lightning damage but only two per thousand that are sail only.

Oh, now I get it. I had just forgot to count the finite number of electrons on my masthead versus the finite number of electrons on my neighbors ungrounded mast. It is all so clear now. If I had counted them themn I would actually have data.