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Re: Lightning- how to avoid

Posted: Fri Oct 19, 2018 5:48 pm
by ronje
Sorry mate.

I tend to go to lengths to prove something is right. Shouldn't do that, I guess.

I'll plead that its a consequence of having to prove things beyond a reasonable doubt during my working life and habits are hard to break.

The sideways stuff is simply cloud to cloud discharges which are mostly hidden by the clouds themselves. Not seeing the discharge stroke in those circumstances, they tend to be simply classed as "sheet lightning" and harmless.

Re: Lightning- how to avoid

Posted: Fri Oct 19, 2018 6:38 pm
by NinjaFish
I've watched the sideways and intricate dancing forks many times in what seems like slow motion to the eye but haven't been able to capture on camera yet.

Another hobby coming one day!

Re: Lightning- how to avoid

Posted: Fri Oct 19, 2018 8:07 pm
by theodosius
Cheers Ronje. To clarify, absolute zero (0 kelvin) is about -273 celcius

Re: Lightning- how to avoid

Posted: Sat Oct 20, 2018 6:19 am
by ronje
Thanks Theodosius.

You're right. I see that I left the 2 out of -273. (-273.2). A theoretical absolute zero temp that's never been reached as I remember past thermodynamics days.

When you said "patient" in one of your posts, what line of interest is that?

Re: Lightning- how to avoid

Posted: Tue Oct 23, 2018 6:37 am
by rumluck
Having a career in working on live high voltage, id firstly GTFO! Then, id be inclined to leave the bimini up for a faraday cage. All rods and antennas down and dont have your head above the bimini line. I dont think the 5-10mm gap in your battery isolator will achieve much in the way of saving your electrics, but each to their own.

Re: Lightning- how to avoid

Posted: Tue Oct 23, 2018 9:19 am
by NinjaFish
I agree with you on the isolator.

It's just what I did at that time.

Re: Lightning- how to avoid

Posted: Tue Oct 23, 2018 7:37 pm
by Dick
NinjaFish wrote:I've watched the sideways and intricate dancing forks many times in what seems like slow motion to the eye but haven't been able to capture on camera yet.

Another hobby coming one day!
Shot these Sunday night along the Gibb. The red brown hue is from dust and smoke from fires

Re: Lightning- how to avoid

Posted: Tue Oct 23, 2018 7:42 pm
by ronje
Fantastic photos. Thanks.

Re: Lightning- how to avoid

Posted: Tue Oct 30, 2018 4:16 am
by NinjaFish
What sort of camera are you using Dick?

This is from the Sunday Terra on what to do in case of....

Re: Lightning- how to avoid

Posted: Sat Nov 03, 2018 6:56 pm
by Dick
NinjaFish wrote:What sort of camera are you using Dick?

Canon 5D but any SLR can take shots similar to that. Just need to be able to keep the shutter open for a while and have the camera sitting still

Re: Lightning- how to avoid

Posted: Sat Nov 03, 2018 7:36 pm
by al57
great pics ,love those storm open shutter pics

Re: Lightning- how to avoid

Posted: Mon Nov 05, 2018 7:00 am
by ronje
Bit more info about lightning.

Part of my job used to be locating electrical interference emanating from power lines. At times I had to go in a bucket truck at night up 66kv (66,000 volt) power lines. Most problems came from 12 kv lines but the more serious ones were from higher voltage lines.

The closest limit for the bucket was 2 metres. A weird soft blue glow (corona - not the beer) was clearly visible along the line and you could feel the electrostatic charge building on body hairs due to the proximity.


In a thunderstorm, the water droplets in the cloud become electrostatically charged and fall to the bottom of the cloud which becomes charged. That electrostatic charge induces an equal and opposite charge on the ground as it passes over.


Higher ground or taller objects (closer to the cloud) have bigger charges induced in them. When the opposite charges have sufficient "electrical tension" between them, the air ionises in narrow channels setting up a discharge path. When the discharge happens, a very small part of the discharge is diverted into these "un-used" channels with the main discharge showing up as a single strike.

But you can still see these much dimmer ionised channels which show up like "forked/branched" lightning strikes.

You can see them easily in Dick's photos.

You need to make sure that YOU or your boat is as low as possible. That's difficult on the water as the boat is the highest thing around.

Don't stake your life on the Faraday Cage stories with the bimini. You'll lose. A Faraday Cage is nothing like a bimini frame.

A Fardady Cage is simply a hollow metal enclosure with either solid sides or a small even-sized mesh enclosure commensurate with the frequency of the electromagnetic radiation comprising the strike. These examples of electrical energy dancing around a person in a cage are under very, very controlled conditions. Don't bet your life that a bimini frame is anything like that 'cos its not.

Look here https://science.howstuffworks.com/faraday-cage.htm

At school we used to do electrostatic discharge experiments with a thing called a Wimshurst Machine. Its exactly how lightning works.

https://www.youtube.com/watch?v=Zilvl9tS0Og

In addition, even if you have a fibreglass roof, it offers zero protection so you still need to get as low as possible

Re: Lightning- how to avoid

Posted: Mon Nov 05, 2018 12:54 pm
by theodosius
So get low and have the boat near higher trees or ground, not on open water? Ie anchor at edge of river instead of the middle of the channel

Re: Lightning- how to avoid

Posted: Mon Nov 05, 2018 4:41 pm
by ronje
That's what I'd be doing.

You can't get any lower than water level so get near a high bank (preferably one higher than you) but not one with taller trees than others in area. Sometimes you won't have a lot of choice but don't stay out in the middle where you'll stand out higher like a pimple on a pumpkin.

Re: Lightning- how to avoid

Posted: Tue Nov 06, 2018 5:06 am
by Eman
Might sound dumb, but in hospital full of drugs so who cares, but would carrying a couple of thick yoga mats in your boat provide any sort of protection? If you are laying flat as a tack in your boat so your not the highest point.