Lightning strikes

[Poey50]

I have a piece of copper rod which I intend to grind the tip to a sharp point and mount to the top of my mast.

Be careful of the copper to alumunium connection ... with salty damp air, that's prone to corrosion. I'm plamning to experiment with the same but with aluminium. rod. (The experiment being the extent to which it interferes with VHF / AIS. If it does, I won't bother.)

 

[coopec]

Be careful of the copper to alumunium connection ... with salty damp air that's prone to corrosion. I'm plamning to experiment with the same but with aluminium. rod. (The experiment being the extent to which it interferes with VHF / AIS. If it does, I won't bother.)

Thanks for that.

I was aware there could be a possibility of galvanic corrosion but was not sure how I would get around the problem. I have to do a bit more research but with an aluminum mast maybe I don't have to bother?

Down conductor

The main purpose of the down conductor cable is to provide a low-impedance path between the air terminal and the external grounding plate. This cable should have a minimum cross sectional area of 21mm2. An aluminium mast is usually of sufficient cross-sectional area to facilitate the necessary lightning flow, but it should be connected by the cable at its base to an external grounding plate in order to complete the circuit. External grounding plate

 

[Poey50]

Thanks for that.

I was aware there could be a possibility of galvanic corrosion but was not sure how I would get around the problem. I have to do a bit more research but with an aluminum mast maybe I don't have to bother?

Down conductor

The main purpose of the down conductor cable is to provide a low-impedance path between the air terminal and the external grounding plate. This cable should have a minimum cross sectional area of 21mm2. An aluminium mast is usually of sufficient cross-sectional area to facilitate the necessary lightning flow, but it should be connected by the cable at its base to an external grounding plate in order to complete the circuit. External grounding plate

The air terminal is just to (attempt to) protect the masthead instruments. The assumption (hope) is that the lighting will travel down the surface of the mast protecting the cables in a Faraday cage. Aluminium is a pretty good conductor.

 

[Newboy6458]

Never been struck by lightning on a boat but a few encounters in aircraft. The first was a classic strike over Alderney in mid autumn. Lovely clear day but occasional large cu-nim build ups. The old crusty in the left hand seat insists on going straight through one that’s smack on route and painting magenta on the weather radar. It’s literally my first line sector after training and I didn’t push for a deviation. Loud crash, can’t see for a few seconds, smell of ozone and everyone’s hair all frizzed out. Nothing seemed broken. Aircraft was a Shorts 360, massively overbuilt in Belfast next to the old Titanic yard of Harlan and Wolf.

 

[coopec]

Never been struck by lightning on a boat but a few encounters in aircraft. The first was a classic strike over Alderney in mid autumn. Lovely clear day but occasional large cu-nim build ups. The old crusty in the left hand seat insists on going straight through one that’s smack on route and painting magenta on the weather radar. It’s literally my first line sector after training and I didn’t push for a deviation. Loud crash, can’t see for a few seconds, smell of ozone and everyone’s hair all frizzed out. Nothing seemed broken. Aircraft was a Shorts 360, massively overbuilt in Belfast next to the old Titanic yard of Harlan and Wolf.

I've flown from Perth to Johannesburg and it takes about 10 hours (all over water). I don't know that authorities have changed the rules but they would only allow 4 engined aircraft to fly the route.

I've always believed when an aircraft gets struck by lightning there's no problem? Apparently though thunderstorms can cause severe turbulence and if an aircraft flies into one it can cause a disaster. Until recently a lot of pilots didn't radar to pick up the turbulence so when they saw thunder stormy clouds they used to fly around the clouds. If it was a moonlit night they could avoid the cloud but if there was no moon they just trusted to luck.

 

[Graham376]

CuNims are normally avoided as the gusts can over stress aircraft. AFAIK we weren't struck but a flight (as a passenger) in wide-spread storm over the Brazilian rain forest was rough enough for pilot to slow down to keep within envelope and the wings had a fine fireworks display. Trolley dollies all strapped in and lots of muttering passengers playing with rosaries

 

[Newboy6458]

Absolutely right. Danger from thunderstorms isn’t just limited to being hit by lightning. We once experienced a 50kt gust front in Greece (no wind Nidri!) when a large thunderstorm dropped millions of tons of cold air into our bit of the Ionian. Surrounded by mountains the downburst was squashed into a relatively small area of sea. It can only fall to sea level and then it goes sideways, quickly. Even with a very small fetch the waves built very quickly indeed. Extremely unpleasant.
Just to add to the spice, not all thunderstorms are isolated and visible. They can join into squall lines and also be invisible when embedded in stratus layers. General rule of thumb, the warmer the weather, the more moisture they can carry and the higher they can grow. Add warm seas and mountains and you have a lovely mixing bowl of great unpleasantness. Nasty things and to be avoided.

 

[Resolution]

Last week sailing along the coast of Cyprus we began to worry about a massive cloud build up to the south. This turned into a major thunder storm with lots of sheet lightning. Gradually more and more strikes into the sea became visible, but the big questions were How far away and Moving in what direction? As the only thing sticking out above the flat sea, we seemed bound to be the point of attractive charge.
Luckily, we have an app called BlitzortungLive and were able to locate the storm precisely and to track the movement of latest strikes. A 90 degree course change took us out of the line of fire and we recorded no strikes on board. Very relieved.

 

[Plymsea]

An update from the guy who video started this thread: