Insurance Requiring a Lightning Rod

[Paul Howard]

I was delivering a friend's 45ft catamaran from Nassau, Bahamas, headed direct for New York. About 180 miles southeast of Cape Hatteras we were struck by lightning. All electronics, batteries and lights were toast. The boat had a Forespar Lightning Master at the top of the mast. The only grounding was through the stainless steel shrouds to an underwater plate.
The aluminum mast is a much better electrical conductor than the shrouds. The main charge went down the mast, jumped to the inverter and battery bank at the interior below the mast step.
Batteries exploded, the engine the electrical panel was grounded through was inoperable. We limped into Chesapeake Bay with no lights, no radio, still sailing and with one engine.
On return to my own catamaran I installed a Forespar Lightning Master, grounded both of the shrouds to an underwater plate at each hull and ran a separate electrical cable from the maststep to a separate grounding plate in the shortest and most direct route to the plate on the inboard side of the starboard hull. Now, several years later, I still think I did the right thing.

[Rumrace]

News flash! I called my insurance agent and was told absolutely. In certain areas and seasons it’s reasonable that the equipment is necessary to mitigate damage as required in the policy. He went on to say changing weather patterns will likely spread the request to eventually being required on new boat builds!
We stuff our things in the oven and keep as much turned off as we can.

[Uncle Bob]

Originally Posted by MoodyS

I had a similar request from my insurers a few years ago, when numerous owners in the Med. were claiming for lightning strike as an economic way of paying for a new suite of electronics. I politely requested details of their approved system suitable for my boat and never heard back. I think most insurers have now realised that better claims investigation is the sensible way to go.

I think this is the best way forward, if they cannot offer equipment suitability advice how can they reject a claim.

[capn_billl]

I have a similar setup.

2 ft 00 gauge Aluminum stranded wire spread out at top of mast (also deters birds), and 00 gauge copper strand electrically connected to shrouds, and just long enough to dangle into water 10 ft.

Good call on the mast step being a lower resistance, I'm adding a ground to that also.

From reading experiences of boats hit by lightning, the charge likes to dissipate from conductors near the water surface.

So a metal plate at least 10 sq ft at the water line will be most effective.

The larger the surface area, the lower the resistance.

[GordMay]

Originally Posted by GordMay

... The lightning air terminal (rod) is fixed at the mast top, which is grounded to a submerged ground terminal (metal keel, gnd strip, SiedarcTM , etc), with minimum #4 AWG cable.

It’s not a dissipator/charge transfer device, intended to prevent a strike.

Correction.

[GordMay]

Originally Posted by capn_billl

...

1. From reading experiences of boats hit by lightning, the charge likes to dissipate from conductors near the water surface.

2. The larger the surface area, the lower the resistance.

1. See Ewen Thomson's "Sidearc" Terminals.
➥ Grounding concepts


2. Indeed. Lightning likes to exit from the edges, of the ground plate, making a long thin metal strip, of at least 1 square foot, most effective [excepting 1 above].

[Franziska]

Any thoughts on how to mitigate lightning energy on a catamaran with a deckstepped mast on the cabin?

So far we have a thickwalled aluminum box (we do not have a formal oven or microwave) in which we place all electronics except one of our nav computers, the AIS and GPS and the fixed antennas like radar.
Further we have a set of 20mm2 cables which we attach to the mastfoot and forestays in case of a lightning storm. The ends of them go into the sea.

Our main petrol reservoir (we only have outboards) is stainless and attached to a stainless through bolt under the waterline as grounding to dissapate static when refueling.

Any thoughts as to how to improve on this?

[GordMay]

Catamarans have their own special set of issues:

”... Now the solution: to address these major issues at the mast base and bridge deck, we are in the process of developing a bridge deck electrode. This is connected via a flexible conductor so that it can be lowered to just above the waterline, for maximum grounding effectiveness, or all the way up to the bridge deck, for clearance while cruising...”

From lightning expert, Ewen Thomson PhD at ➥ http://www.marinelightning.com

➥ Catamarans

Grounding Concepts ➥ http://marinelightning.com/Informati...ngConcepts.htm

There’s several Lightning Protection Systems for Catamarans, featured here:
➥ Systems Gallery

[mako]

Why is a cat, with a mast height the same as a mono, more likely to be hit by lightning?

[bdgWesternMass]

Originally Posted by mako

Why is a cat, with a mast height the same as a mono, more likely to be hit by lightning?

More surface contact with ground/water is thought to be better source to ground then less surface area.

[GordMay]

Both UK and US-based insurers report that multihulls are two to three times more likely to be struck by lightning, than monohulls, due to the increased surface area, and the lack of a keel, causing difficulties with adequate grounding.

According to Ewen Thomson (Marine Lightning Protection Inc.):
According to Boat US insurance claims, catamarans are struck twice as frequently as monohulls of similar length, and they also sustain more damage per strike, than sailing monohulls with auxiliary power. .
• They do not come with an in-built lead ballast that can be used as part of the grounding system.
• Their two hulls mean that there is twice as much waterline to contend with.
• The bridge deck being suspended above the water introduces yet another vulnerability for sideflashes.
More ➥ Catamarans

[Franziska]

Originally Posted by GordMay

Catamarans have their own special set of issues:
From lightning expert, Ewen Thomson PhD at ➥ http://www.marinelightning.com

➥ Catamarans

Grounding Concepts ➥ http://marinelightning.com/Informati...ngConcepts.htm

There’s several Lightning Protection Systems for Catamarans, featured here:
➥ Systems Gallery

Thank you Gord, very interesting solution.
Probably we can add something like this too.

[Nicholson58]

Originally Posted by Mike Banks

You asked for proper advice and you got very little if any, at best of little real value at all beyond a statement of purpose, and at worst, stupidity and dangerous advice.

If your insurance wanting to make you and your family and crew safer at sea it is the only reason for fitting it, you are not a skipper with whom I would venture offshore.

I would not put to sea without lightning protection, and having it will not "Attract lightning to your boat" Quite the reverse--and if you DO get a strike it will lessen the damage you will sustain.

I used to work on transmission lines and towers--and without lightning protection, the damage each year to outside plant and equipment would have been unaffordable.

Just ensure your lightning protection earth system on the vessel is a standalone system separate from any other radio equipment.

Do your OWN research. Lightning and the transient atmospheric conditions during electrical storms are a fascinating read.

We have a ‘Fuzzy’ on our mast head. There are hundreds of feet of 4” wide copper in the bilge and up the sides. All mast, shrouds and lifelines are part of this giant Faraday cage. We have multiple ground plates. We have been struck three times in the Great Lakes. The last was a devastating direct hit that lit up the insides for a while. Bits of melted metal were all over the deck from antennas, wires, Windex. The only thing that survived on top was the Fuzzy so I suppose it protected itself. Many electronics were fried. I can say that the several electric items that were isolated by two pole air gap switches interrupting both + & - leads survived.

I too have never heard of a lightening rod on a boat. There are a few commercial devices available such as my Fuzzy but I rate them as a crap shoot. Find a carrier who knows boats.

[TabbyCat]

Originally Posted by CYNAEM

.. as part of getting insurance the provider is requiring a lightning rod for them to cover a lightning strike. ... Not sure what to do. Any suggestions would be greatly appreciated.

OK, that is truly weird. I have been in the marine insurance field for over 18 years and I have never had an underwriter ask for a client to have a lightning rod. Perhaps your agent is in the business of selling them ?

I'm not saying that some sort of protection is not a good idea (I have a system on my own catamaran). I am saying that I do not know of any marine ins underwriters that specify that you have that equipment, and I write coverage with a lot of reputable companies. I would be very interested to know what company (not the agent name, the actual underwriting company) asked you for this?

[BBill]

Originally Posted by Mike Banks

You asked for proper advice and you got very little if any, at best of little real value at all beyond a statement of purpose, and at worst, stupidity and dangerous advice.

If your insurance wanting to make you and your family and crew safer at sea it is the only reason for fitting it, you are not a skipper with whom I would venture offshore.

I would not put to sea without lightning protection, and having it will not "Attract lightning to your boat" Quite the reverse--and if you DO get a strike it will lessen the damage you will sustain.

I used to work on transmission lines and towers--and without lightning protection, the damage each year to outside plant and equipment would have been unaffordable.

Just ensure your lightning protection earth system on the vessel is a standalone system separate from any other radio equipment.

Do your OWN research. Lightning and the transient atmospheric conditions during electrical storms are a fascinating read.

Thank you Mike. I posted the same thing a few yrs ago and got thrashed as giving bogus info. Your experience reflects the exact same info i received from an old timer electrician who owned a high power electrical company for over 50 yrs. He had one story where a cattle rancher friend had a wooden tower with windmill pump on top. Sitting on a flat sawgrass flood pIain and the highest structure for miles. It was struck and damaged every yr or so for decades. After grounding it wasn't damaged from a strike for 10 yrs and counting. He put the same system on his sailboat.