Planning lightning prevention system on catamaran

[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

[Salerosi]

Placas de cobre a cada costado del casco
Conexión orza mediante tornillos soporte por medio de pletina de cobre 0,5mm o línea de 35mm con terminales prensados y soldados con estaño, todo equipo este en contacto con agua, salada o dulce debe estar conectado a las placas de cobre mediante difurcadores, una entrada de línea 35mm a otras de 10mm mínimo, incluido las griferías de todos los aseos y depósitos

[Piscis]

Originally Posted by Salerosi

Placas de cobre a cada costado del casco
Conexión orza mediante tornillos soporte por medio de pletina de cobre 0,5mm o línea de 35mm con terminales prensados y soldados con estaño, todo equipo este en contacto con agua, salada o dulce debe estar conectado a las placas de cobre mediante difurcadores, una entrada de línea 35mm a otras de 10mm mínimo, incluido las griferías de todos los aseos y depósitos

Thank you very much!

So you would not worry too much because of copper and seawater corrosion?

I read already that pure copper has the best conductivity. However, in seawater there might be corrosion issues?

Tinned copper cables and pure copper plate at the keel?

Thanks!

John

[hjohnson]

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

There’s no such thing as lightning prevention. Lightning will do whatever it wants to do. All you can do is make sure that the lowest impedance connection to the ocean does not flow through anything critical. We’re talking large conductors, solid connections (preferably cadwelded), and no real bends.

[Piscis]

Thanks, i understand that!

I need to install, because insurance requirements. AND if i install something that will be ugly and maybe awkward, at least i want it to have a chance to work and not cause more problems then i already have... LOL

Copperplate and wires... Corrosion in Seawater?
Better go Stainless?
Better go Aluminium?

I know about the conductivity, copper will be best....

Any thought?

Thanks!

John

[s/v Jedi]

Originally Posted by Piscis

Thanks, i understand that!

I need to install, because insurance requirements. AND if i install something that will be ugly and maybe awkward, at least i want it to have a chance to work and not cause more problems then i already have... LOL

Copperplate and wires... Corrosion in Seawater?
Better go Stainless?
Better go Aluminium?

I know about the conductivity, copper will be best....

Any thought?

Thanks!

John

Can you literally write their demands/requirements? Do they know you have a catamaran?

[deblen]

A Dynaplate was the usual choice for a "Ground" plate.
Equivalent to 1sqft copper.


https://www.cruisersforum.com/forums...ay-143199.html

[capn_billl]

Originally Posted by Piscis

Thanks, i understand that!

I need to install, because insurance requirements. AND if i install something that will be ugly and maybe awkward, at least i want it to have a chance to work and not cause more problems then i already have... LOL

Copperplate and wires... Corrosion in Seawater?
Better go Stainless?
Better go Aluminium?

I know about the conductivity, copper will be best....

Any thought?

Thanks!

John

Everything corrodes in salt water, but Copper corrodes the slowest besides bronze.

For underwater I'd use the same metal as your props, and anode protect similarly.

I've heard of Catamarans lightning strikes jumping from base of mast through the bridgedeck. So I'd start there.

You want to comply with insurance, but you might as well make a working system while you are at it.

Ignore the people who say, "there is nothing you can do".

That's complete ********!

Like saying a hardhat can't protect you from a 10-ton rock so why wear it?

Or a seatbelt can't protect you from a 200mph collision with a semi, so why wear it?

We've know how to protect ourselves from lightning since 1770 when Ben Franklin flew his kite, then invented lightning rods.

This is 200-year-old technology, and still works.

We protect buildings, cell towers, and radar with a simple ground wire that works 99% of the time.
Ground it. and use a big wire.

Planes are protected by conductive spikes that protrude into the airstream.

Boats have a similar issue that we aren't permanently connected to the ground.

For the Ocean you have a perfect conductive ground, you just need enough surface area to dissipate the current.

AN 0 guage wire will conduct thousands of amps for the second or two required to absorb the strike.

Ideally you would need 9 sq ft of grounding plate in contact with water to dissipate a major strike.

For boats with metal keels this is simple.

For fiberglass it's a lot more challenging, but you just need a well bonded conductive sheet at the waterline.

Right now I use 9 sq ft of copper mesh attached to 0 guage braid bolted to chainplates that I throw overboard when I see lightning.

Studies of strikes show the bulk of the discharge occurs at the waterline.

There is a company that makes through hulls with discharge spike similar to those use on airplanes at the waterline.

Unfortunately, the cost is better suited to superyachts.

One of my to do, is the next haulout add a copper strip all around the hull at the waterline.

Epoxy to hull, and paint with copper paint (bright blue to match existing stripe). I can permanently bond a conductive strip up the hull to Chainplates.

You could cover the braid going up with thin gel coat for appearance.

I hope this helps.

[team karst]

I made my own surface discharge thru hulls. Using 3/4” marelon and 1/2” SiBronze threaded rod. I sharpened the tip and epoxyed the rod in the marelon.
Copper strap from chain plates to t/h. Bronze nuts holding rod to strap.
Installed all 3 t/h about 2” above loaded waterline.

[Piscis]

Thanks all for your help!

Originally Posted by s/v Jedi

Can you literally write their demands/requirements? Do they know you have a catamaran?

Yes the insurance knows about my vessel. In the insurance policy claims are excluded if:

"For lightning strikes on sailing vessels where a lightning rod is not attached to the mast"

However, i asked to clarify this and asked for detailed specifcations about the lightning protection and received the following written change to that clause:

"In terms of the best lightning conductor, if you already have an aluminium mast, then you only need to ground the mast itself and the metal shrouds to an earth block on/through the hull."

We have a Z Spar Aluminium Mast.

John

[s/v Jedi]

Originally Posted by Piscis

Thanks all for your help!




Yes the insurance knows about my vessel. In the insurance policy claims are excluded if:

"For lightning strikes on sailing vessels where a lightning rod is not attached to the mast"

However, i asked to clarify this and asked for detailed specifcations about the lightning protection and received the following written change to that clause:

"In terms of the best lightning conductor, if you already have an aluminium mast, then you only need to ground the mast itself and the metal shrouds to an earth block on/through the hull."

We have a Z Spar Aluminium Mast.

John

That is a pretty tough task. You would probably need three of the thru-hull electrodes above waterline at each hull where the chainplates for shrouds and backstays are, as well as where the forward beam attaches.
From the bottom of the mast to the nearest electrode as well.

[Piscis]

Did some further research...

Looks like Beryllium Copper has a very good conductivity (40-60% of copper) and is not corroding in seawater.

So maybe the best combination would be:

- max possible sizzed cables made from tinned copper as conductors to grounding plate
- Connectors Beryllium Copper
- Grounding plate at the keel Beryllium Copper

Connect port and stb shrouds straight down to grounding plate at keel
Connect Mast (unfortunatelly via some bends...) to grounding plate
Connect bow Aluminium Crossbeam to grounding plate (Genoa roller metall might carry high current and loads in case of lightning strike)

Trying to find a compromise not making it too ugly, satisfying inssurance requirements AND having some positive effects in case of lightning strike...

Lets see.

Thanks again!

John

[team karst]

The best lightning conductors are either straps, or the stranded copper furnished by the likes of Harger. For a boat, choose strap. Check out georgia copper. I dont think i have use BeCu in other than tempered spring applications. Sounds exotic/expensive in big items.

[s/v Jedi]

ABYC has requirements for the conductor… from memory it needs to be fine stranded copper of at least 6AWG.

[team karst]

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