Planning lightning prevention system on catamaran

[CaptainRivet]

Originally Posted by Piscis

Our insurance company requires a lightning rod or a prevention system. So i am planning to install one, regardless of if it works or not...

Their requirements: No rod on top of mast needed. Mast and shrouds have to be grounded to a metall plate, best at the keel.

I found this, aged, information:

https://nasdonline.org/7182/d000007/...rotection.html

Planning according their recomendations:

Grounding mast and shrouds with an at least 8 AWG cable, shortes way, to a copper plate at the keel.
Grounding bow crossbeam same way, as Genoa furler might act as a conductor as well.
Planning two Copper plates, sizzed at least 1 SQF at each keel.
All press fit connectors from copper.

All parts and connectors Copper, mast is Aluminium, shrouds stainless steel. Any corrosion problems accuring with this combination?

How to route the conductor cables? Use glue on spacers? Would it be possible to route the cable inside the hulls? Outside might look... strange...

Any ideas you have, please let me know! I am still in the planning phase so open for suggestions.

Not easy to get anybody experienced for an installation of that kind in SE Asia.

Thanks!

John

Originally Posted by Piscis

Our insurance company requires a lightning rod or a prevention system. So i am planning to install one, regardless of if it works or not...

Their requirements: No rod on top of mast needed. Mast and shrouds have to be grounded to a metall plate, best at the keel.

I found this, aged, information:

https://nasdonline.org/7182/d000007/...rotection.html

Planning according their recomendations:

Grounding mast and shrouds with an at least 8 AWG cable, shortes way, to a copper plate at the keel.
Grounding bow crossbeam same way, as Genoa furler might act as a conductor as well.
Planning two Copper plates, sizzed at least 1 SQF at each keel.
All press fit connectors from copper.

All parts and connectors Copper, mast is Aluminium, shrouds stainless steel. Any corrosion problems accuring with this combination?

How to route the conductor cables? Use glue on spacers? Would it be possible to route the cable inside the hulls? Outside might look... strange...

Any ideas you have, please let me know! I am still in the planning phase so open for suggestions.

Not easy to get anybody experienced for an installation of that kind in SE Asia.

Thanks!

John

Save yourself the money, your insurance won't pay anyhow, they find some other stuff in the small print to deny the claim. That they also don't care how it works shows they have no glue and requirement was nailed together by an underwriter in theorie at his desk...was 25 years in top management in claims at big insurer...stay away from Pantaenius, they are the worst as their smallprint exclude nearly everything but that is coded that even laywer cannot tell you its 100% covered. They went from a top insurer to the worst in 3 years, reason is Allianz pulled out as backup insurer in the whole caribean, their combined ratio is totally out of balance (too many damages and now tons of court cases with damage costs exploding) and new head of claims (who is an hardcore a...hole) changed startegy. In Germany all other insurer right away involve now law department if Pantaenius is involved in a claim.
My advice look for different insurance without that requirement.

[mvweebles]

Decent article on lightning protection from Steve D'antonio

https://stevedmarineconsulting.com/l...self-regulate/

[Tin Tin]

check this out:
https://boattest.com/article/ground-plate-installation

[GALAWA]

Dear cruising friends.
Being an Electrical Engineer, with first hand experience of lightning strikes aboard my 43' catamaran, I am happy to share some ideas in the matter of lightning.

This thread was kicked off by an insurer requiring a lightning rod on a sailing boat. This insurer is exposing his ignorance of the matter.

Assuming your mast is aluminium, it is in itself a very efficient lightning rod towering 10 to 30 meters above your ship and the sea surface.
It is actually too efficient as it will attract lightning in a several hunded meters radius around the boat. Were it not for the mast, lightning might have struck the sea nearby with little harm.
( If the lighning strike is close enough, it may still kill your VHF spliter by induction in the mast cables)
Unless you have a wooden mast, there is absolutely no point adding a lightning rod on top of the mast !

Assuming your shrouds are steel, ( i.e.: not non conductive Dynema)

One of your chain plates (of top shroud or of back stay, one is enough) should be connected with a heavy gage copper wire or copper band to a bolt of the iron keel (in case of cast iron keel on a mono hull).

In the case of a fiberglass encapsulated lead keel isolated from the sea,
or in the case of a catamaran where "keels" are non conductive fiberglass fins, the copper wire or copper band should be connected to a 1 square foot metal (copper) "sea-plate" attached outside the hull well below the waterline so that it remains submerged when the boat heels or the sea is rough.

When ligning strikes your mast (as it happened to my catamaran), the kilo-amps will flow to the sea, mostly via the iron keel or sea-plate)

I say mostly, because, depending on the energy of the lighning strike,
the kilo-amps will find additional ways to reach the sea through the engine and sail drives (killing the starter motor and alternator), the regrigerator's keel cooler (killing the refrigerator's compressor), or worse through the steel armature of the plastic pipe between the bronze through hull and the engine's colling water pump.
In this worst case scenario, the steel armature is vaporised and the pipe severed, leaving one (or several) disconnected throughhulls open to flooding, beyond the capacity of bilge pumps ( which are probably dead after lighning anyway).

Without a sea-plate connected to a chain plate, the kilov-olts and kilo-amps will find their own way to the sea : Expect the worse: hull punctered + fire aboard.

So priorities after the strike are ;
1- Is the crew safe, ( no cardiac massage required )
2- Is there fire aboard (that schould be easily ascertained)
3 -Are we sinking : Lift all floor board and investigate the bilges and engine hold seriously)

Having found no one hurt, no fire and no sinking... you are not done yet

At the mast top you have a wind sensor, a VHF antenna and
navlights, all three duly connected by electric cables down the mast into the boat.
With or without a lightning rod they will all be reduced to charcoal by lightning.

Through these 3 cables the kilovolts (50 Kv, 100 Kv..) descend into the boat on a rampage, toasting all your electronics, (AIS, VHF, Chartplotter, Radar Auto pilot's computer, inverter, generator, randomly shorting your wire looms, killing bilge pumps, starters, electric winches..etc..)
In the cabin we found shards of glass on the bed sheets .. from exploded light bulbs in the ceiling !
We had 30 000 $ dammages.

"Luckily", an Ipad fitted with Navionics was spared as it was not connected for charging . It afforded us navigating means as we sailed on "by hand" toward Tahiti.

The only possible defense against the Kilo Volts rampage is to fully isolate the boats electric network from the cables in the mast and the mast itself.
In all production boats, the connectors are hardly accessible, and will not be disconnected if and when a chance of lightning is perceived.

To encourage zelous disconnection of mast cables, all cables coming from the mast should be led to an easily accessible "switchboard" where all cables can be disconnected with minimum 1 inch air gaps with simple gestures.

Yet there is no garanty this will suffice. Think of the KiloVolts going down the forestay, to the pulpit, the navlight in the pulpit, the 12 v cable of the navlight.... .

And when you feel safe , say back in some marina, and take stock of dammages with the help of some professional electrician , you are still not done yet :
In your home ashore, 220 V or 110 volts will immediatly turn an electrical fault into a shortcircuit tripping a breaker.
Not so aboard your 12 Volts ship! The fault will simmer and burn slowly, and 2 weeks after the strike a pump' motor which still worked fine after the strike will be reduced to charcoal, the starter motors will die , etc....

We were voyaging in the Pacific when lightning struck. Procuring the spare equipment and repairing our catamaran took 3 months.

[capn_billl]

Originally Posted by team karst

Attachment 276760
Attachment 276761

Too early for my recommendation. But its my trial. I have successfully steered a direct hit with it shoreside

Is that the crossbeam bolt?

[capn_billl]

Originally Posted by smj

We have the SS toilet brush on top of the mast attached to a #4 wire that runs straight down, through the deck and bridgedeck and into the water, no bends or turns in the wire.

My only concern with this system is attenuation of the VHF signal if located too close to antenna.

How much separation is your antenna, and have you noticed any signal degradation?

[capn_billl]

Originally Posted by Piscis

Great advice here thanks a lot!

So basically i have an idea what to do. One thing bothers me a bit. How bad will it look when installed.

Thinking of how to route the cables/straps down into the water. Easy way will be the most ugly way. From the shrouds down at the sides all the way down to the keel. However, i would prefer something more hidden... Any idea how to route the conductors more hidden?
Inside the hulls, between interior covers and the hulls? How to go through the glass?
Any conductive through hulls out there? Or route cable/straps through a conventional through hull, attached a hose that goes above waterline?

Stupid idea?

Something to keep in mind.

The lightning strike will generate a substantial field around the ground wire.

This will not only cause the wire to be surrounded by corona discharge, but it will create induced charges in surrounding conductors.

Obviously, any grounding will be better than none, but it will be more challenging to steer around other wiring, and sensitive devices, and also keep straight short runs if routed inside your boat.

[team karst]

Originally Posted by capn_billl

Is that the crossbeam bolt?

Affirmative. Bolted bracket that is welded to actual beam.

Impulse mag field is the EMC lab name for study of transient, radiated, very large current effects of electronics. Difficult if not impossible to reduce/control that field. A boat is just a hapless conductor. Not unlike aircraft, except they get tested. [emoji106]

[capn_billl]

Originally Posted by GALAWA

Dear cruising friends.
Being an Electrical Engineer, with first hand experience of lightning strikes aboard my 43' catamaran

, it may still kill your VHF splitter by induction in the mast cables)
Unless you have a wooden mast, there is absolutely no point adding a lightning rod on top of the mast !

.

All good points, but I have a small disagreement with this one.

While there is no stopping a major strike, I would still rather the initial point of contact be a metal rod than my VHF, Windex, and anchor light.

MY experience is While there was a bright flash, and boom at the top of the mast, my well protected electronics only rebooted several times.

A few months later my Wind indicator, and instrument suddenly stopped working. and required replacement, and one tank level indicator on my Nema2000 network randomly gives error messages.

SO most lightning strikes are survivable if you have everything well bonded with lightning arrestors attached to electronics, and grounding from mast top to a conductive plate at the waterline according to the latest ABYC standards.

[capn_billl]

Originally Posted by team karst

Affirmative. Bolted bracket that is welded to actual beam.

Impulse mag field is the EMC lab name for study of transient, radiated, very large current effects of electronics. Difficult if not impossible to reduce/control that field. A boat is just a hapless conductor. Not unlike aircraft, except they get tested. [emoji106]

Sweet, that might be easier, and more direct than going from a shroud, and the bow is further from sensitive areas.

[s/v Jedi]

Originally Posted by smj

We have the SS toilet brush on top of the mast attached to a #4 wire that runs straight down, through the deck and bridgedeck and into the water, no bends or turns in the wire.

You are using a static dissipator as a lightning rod. It isn’t made for that and won’t survive a strike.

But it is correctly connected as a static dissipator. This won’t prevent a lightning strike, but the bolt may seek another target instead.

I like to explain it as being camouflage, to make yourself less visible to lightning.

(It tries to prevent or slow down the forming of a leader)

[team karst]

Originally Posted by capn_billl

Sweet, that might be easier, and more direct than going from a shroud, and the bow is further from sensitive areas.

I have both side shrouds similarly Cu strip linked to their own t/h at waterline.
In hindsight, I could have easily done electroless Sn coating on the bare copper.
Similar process to old time PCB tin plate. The strips are .020 or .030" thick, as I recall. About AWG4 equiv.

[capn_billl]

Originally Posted by capn_billl

All good points, but I have a small disagreement with this one.

While there is no stopping a major strike, I would still rather the initial point of contact be a metal rod than my VHF, Windex, and anchor light.

MY experience is While there was a bright flash, and boom at the top of the mast, my well protected electronics only rebooted several times.

A few months later my Wind indicator, and instrument suddenly stopped working. and required replacement, and one tank level indicator on my Nema2000 network randomly gives error messages.

SO most lightning strikes are survivable if you have everything well bonded with lightning arrestors attached to electronics, and grounding from mast top to a conductive plate at the waterline according to the latest ABYC standards.

Woops, add the inverter to the list. it just smoked, and died.

[smj]

Originally Posted by capn_billl

My only concern with this system is attenuation of the VHF signal if located too close to antenna.



How much separation is your antenna, and have you noticed any signal degradation?

We moved the antenna down to the deck mounted radar mount, so nowhere near the toilet brush.

[smj]

Originally Posted by s/v Jedi

You are using a static dissipator as a lightning rod. It isn’t made for that and won’t survive a strike.



But it is correctly connected as a static dissipator. This won’t prevent a lightning strike, but the bolt may seek another target instead.



I like to explain it as being camouflage, to make yourself less visible to lightning.



(It tries to prevent or slow down the forming of a leader)

It’s what the boat came with, but I believe a good prayer would help just as much, and I’m agnostic.