LIGHTNING

[team karst]

I did 145 and 440 MHz.

[GordMay]

Originally Posted by team karst

I did 145 and 440 MHz.

I don't know a lot about this subject, but, evidently:
"Lightning is known to emit significant electromagnetic energy in the radio-frequency range from below 1 Hz to near 300 MHz, with a peak in the frequency spectrum near 5 to 10 kHz for lightning at distances beyond 50 km or so."
➥ https://library.wmo.int/doc_num.php?explnum_id=3184

[team karst]

Originally Posted by GordMay

I don't know a lot about this subject, but, evidently:
"Lightning is known to emit significant electromagnetic energy in the radio-frequency range from below 1 Hz to near 300 MHz, with a peak in the frequency spectrum near 5 to 10 kHz for lightning at distances beyond 50 km or so."
➥ https://library.wmo.int/doc_num.php?explnum_id=3184

Ah, but you already knew that. Static crashes on AM broadcast radio.

[tkeithlu]

Chotu, buried in the numbers could be that monohulls and multihulls are actually as prone as each other to strikes or near misses, but the damage (and insurance claims) worse in multihulls. Near misses can wipe out electronics or do nothing dependent on grounding paths available, and will be called strikes if damage was done. So can hits, but with much more severe damage likely.

A neighborhood hit reprogrammed my garage door openers for me last week....

[GordMay]

Originally Posted by team karst

Ah, but you already knew that. Static crashes on AM broadcast radio.

Yes, I knew (but didn't consider) that the AM radio band goes from 540 KHz to 1600 KHz (or 1.6 MHz).
What I didn't know (or remember), was that those frequencies corresponded with lightning's peak in the spectrum.

[team karst]

If you study the atmospheric propagation, the AM broadcast band has a short range in the daytime, due to what's called signal absorption. Lots of sun excited ions in daytime. But, at nite, the story changes. You can hear lightning static crashes from a thousand miles away.

[team karst]

Originally Posted by tkeithlu

Chotu, buried in the numbers could be that monohulls and multihulls are actually as prone as each other to strikes or near misses, but the damage (and insurance claims) worse in multihulls. Near misses can wipe out electronics or do nothing dependent on grounding paths available, and will be called strikes if damage was done. So can hits, but with much more severe damage likely....

Chotu and i have had this conversation. I suggested metal shrouds for the purpose of determining the path of the strike. Left only to a metallic mast attached to a composite crossmember, bad things will happen.
In a nutshell; give the strike current a safe and predictable path to the water's surface

[GordMay]

Originally Posted by tkeithlu

Chotu, buried in the numbers could be that monohulls and multihulls are actually as prone as each other to strikes or near misses, but the damage (and insurance claims) worse in multihulls...

Not according to BoatUS.
According to reports from BoatUS Marine Insurance claim files, the odds of a boat being struck by lightning in any year are about one in 1,000.
Multihull sailboats are struck roughly twice as often as monohulls.
Even accounting for the fact that a large percentage of multihulls are in lightning-prone Florida, the odds of multihulls being struck are still statistically much greater.

How Likely Is Your Boat To Be Struck By Lightning? ➥ https://www.boatus.com/expert-advice...k-by-lightning
Striking Lightning Facts ➥ https://boatus.com/expert-advice/exp...ightning-facts
Lowering The Lightning Odds ➥ https://www.boatus.com/expert-advice...lightning-odds
Lightning! Flash, BANG! Your Boat's Been Hit — Now What? ➥ https://www.boatus.com/expert-advice...n-hit-now-what
Modern Lightning Protection On Recreational Watercraft ➥ https://www.boatus.com/expert-advice...nal-watercraft

Type of Boat Chances per 1,000
Multihull Sailboat 6.9
Monohull Sailboat 3.8
Bass Boat 0.1
Runabout 0.1
Pontoon Boat 0.1
Overall Average 0.9