Lightning -- to ground or not to ground, that is the qn

[Nicholson58]

Originally Posted by aberglas

TE-4 makes an interesting note about conductors needing to be mainly vertical. I suppose this combination of current and static electricity is in a hurray to get to ground!


I am grounding my mast with a thick cable connected to a chain in the water. Will only put it out when there is lightning about. may do something more permanent later. Like most glass boats, it has nothing at all now.


Apparently something like 1% of yachts get struck each year in lightning prone areas.

1% hahahaha!

Old school: we have bonding of the mast to the 10” X 24” & 4” X 8” grounding plates. There is 4” wide heavy copper strip bow to stern & port to starboard, many strops. All metal rigging and stanchions are tied to this. This is supposed to approximate a Faraday cage. We have a fuzzy on the main mast head.

Despite this, we have been struck three times. Midwest & northern summer storms are brutal. The last hit in Muskegon, Michigan was a massive direct hit witnessed by a charter fishing crew. The list of wrecked stuff is long including both devices and wires.

The possibility of a lightning strike depends a lot on your cruising grounds. Roxy has been struck once in Florida and twice in Muskegon, Michigan. In the Caribbean we rarely see lightning. One Michigan hit was on land. Equipment lost or not has demonstrated a method to minimize the risk. Most Electronic gear is never totally off. The off button only commands a sleep mode. You can pull the breaker to truly de-power but the device is still connected to several feet of plus side wire and the minus side is tied to the entire ground wire side of the whole boat. Lightning causes significant induced spikes in the wiring. We observed after a hit that our devices connected by short wires through two-pole air gap switches were un damaged. Therefore, these local rocker switch disconnects have been added to isolate electronics.

If a storm is coming or if you leave the boat unattended we suggest:

Turn off all unnecessary breakers at the panel
Turn off all two pole rocker switches
Remove the separate stereo front face panel
Turn off all power and wiring (switches) to NAV equipment, radar, depth.
Unplug the main mast wiring (on Roxy, 48 pin monster plug)
Unplug antenna connectors at the foot of the main mast & in the wire chase at the radio, AIS
Unplug external charge controllers
If dockside, shore power off and unplug.

[s/v Jedi]

Disconnecting from shore power is 90% effective for boats in a marina so the #1 thing to do.

When we leave the boat in a marina or on the hard, we run a simple extension cord from shore outlet straight to a dehumidifier or window A/C unit.

[CarlF]

The problem I see is that all of these lightening prevention ideas are focused on a strike hitting the mast and then blowing a hole in the boat as it exits to the water.

But most of the ligthening strike damage is not this. The big problem is a surge getting into the wiring and networks. The result is destroyed chartplotters, solar controllers, radios, bilge pumps, inverters, engine controls and so forth.

A surge that comes up the shore power cable or hits a nearby boat and transmits through the water to your boat's saildrive or prop shaft can do as much or more damage than a strike to the mast.

Does anyone know a lightening protection system that's tested and designed to protect electrical devices. Will a ground wire connecting the mast to the water keep a surge out of the electrical system?

[FlyingScot]

Originally Posted by dannc

Cats MIGHT have taller masts but I don't think that is the reason they get hit more often by lightning. My guess is that they have more water line than mono hulls.

Later,
Dan

I understand it is because they are twice as wide.

Any cone of protection idea from other taller structures don't work as well for catamarans.

[s/v Jedi]

Originally Posted by CarlF

The problem I see is that all of these lightening prevention ideas are focused on a strike hitting the mast and then blowing a hole in the boat as it exits to the water.

But most of the ligthening strike damage is not this. The big problem is a surge getting into the wiring and networks. The result is destroyed chartplotters, solar controllers, radios, bilge pumps, inverters, engine controls and so forth.

A surge that comes up the shore power cable or hits a nearby boat and transmits through the water to your boat's saildrive or prop shaft can do as much or more damage than a strike to the mast.

Does anyone know a lightening protection system that's tested and designed to protect electrical devices. Will a ground wire connecting the mast to the water keep a surge out of the electrical system?

Please look at the threads I started on this, where I include diagrams. Just a search for surge suppressor should work

[Nicholson58]

I agree with Jedi. Note my post #31. Also, this topic starts anew several times a year. Do a search on CF.

There is no sure way to prevent a hit but there are ways to minimize the damage.

[dannc]

Originally Posted by FlyingScot

I understand it is because they are twice as wide.

Any cone of protection idea from other taller structures don't work as well for catamarans.

If the zone of protection is large enough to cover the bow and stern of the cat, the zone should be able to protect the width of the beam of the cat.

The zone of protection is based on the height of the mast as well as the current of the lightning current. The EN 62035 standard has the rolling ball radius running from 20m/67ft to 60m/200ft. Without playing around with a drawing, one would think most cats have a tall enough mast, that even the small 20m/67ft radius, would cover the beam of the boat.

Power boats might have a problem.

Later,
Dan

[CarlF]

Originally Posted by s/v Jedi

Please look at the threads I started on this, where I include diagrams. Just a search for surge suppressor should work

My apologies - I must be blind because I can't find your thread that covers surge protection in wiring. Would be very interested.

But while looking I came on this link that discusses surge protectors in NMEA2000 cabling from nearby strikes (not direct hits).

Looks very interesting. The author also discusses trying to reduce surges in the 12v wiring by using LOTS of ferrite clips to clamp the surge. Anyone tried this? Even if it only worked partially it might reduce the carnage

https://trimaran-san.de/en/protectin...tning-strikes/

[Nicholson58]

After three hits, we sailed Muskegon, Michigan to Marquette and tied up in Cinder Pond Marina. It’s surrounded on two sides by tall hills and a tall hotel with antenna towers. A third side is flanked by the antique ore dock and topped with metal railings. A typical huge Midwest electric storm moved through. Note my post 31. We shut down and disconnected everything and watched a few direct hits on the ore dock. Our last big hit had been only two weeks earlier. Being in this hole even our 80 foot main mast was below the grounded metal ring above us. Fortunately, no new damage.

[team karst]

Originally Posted by CarlF

….

Looks very interesting. The author also discusses trying to reduce surges in the 12v wiring by using LOTS of ferrite clips to clamp the surge. Anyone tried this? Even if it only worked partially it might reduce the carnage

https://trimaran-san.de/en/protectin...tning-strikes/

Few ferrites work below 1 MHz. Mix 73 might help.

[s/v Jedi]

Originally Posted by CarlF

My apologies - I must be blind because I can't find your thread that covers surge protection in wiring. Would be very interested.

But while looking I came on this link that discusses surge protectors in NMEA2000 cabling from nearby strikes (not direct hits).

Looks very interesting. The author also discusses trying to reduce surges in the 12v wiring by using LOTS of ferrite clips to clamp the surge. Anyone tried this? Even if it only worked partially it might reduce the carnage

https://trimaran-san.de/en/protectin...tning-strikes/

I have multiple:

https://www.cruisersforum.com/forums...cs-270317.html

https://www.cruisersforum.com/forums...nt-277406.html

https://www.cruisersforum.com/forums...gn-277396.html

So that’s one for DC power for electronics, one for wind instrument wiring and one for antenna coax wiring

[skenn_ie]

Penetrox/Noalox zinc penetrates aluminium oxide ? I highly suspect claim IMO. Aluminium oxide is very hard, hence used for "sand"paper. Almost nothing will penetrate it other than chemical agents, certainly not a soft metal like zinc.

[skenn_ie]

A iron-powder transformer core with several turns would help with noise suppression. Simple clip-on ferrite baluns, not. They would only attenuate HF noise.
Baluns close to the antenna are useful to improve radio performance. Considered essential in composite aircraft.

[s/v Jedi]

Anodized aluminum is not conductive until you pierce through the anodizing.

[chicagocpo]

Originally Posted by aberglas

Normally I would use some anti-corrosion paste between stainless and aluminum. But for this I do not want an insulated connection! There is probably a better way.

Go ahead and protect your metals from galvanic corrosion. The bit of paste will not be an impediment to a 300MV discharge leaping across an air gap measured in miles. At potentials that high current travels down the surface of the conductor and not the interior anyway.