12v EMP

[nfg2u]

Has anyone ever installed a 12v EMP to protect from lightning strikes? I have seen these on the market. I am asking as I just lost another $1000.00 to lightning. Every storm now I get anxious waiting for the axe to fall. I hate spending so much time getting all my electronics working only having and surge from lighting at the dock taking everything out.

Thanks in advance... yes I live in South Florida.

 

[Chief RA]

Have not used an EMP. I have stated that wrapping your anchor chain around your mast and dropping the anchor over the side is what I recommend. Taking the least restrictive path to ground or water is what the strike will do. Based on my lifelong profession in electronics I think this method makes since. Hope this helps, Chief

 

[rgranger]

I actually do something similar. I have a few links of chain with a snap hook that I clip to the shrouds and toss over the side when I’m anchored out and a storm pops up. I can’t say that it works or not

 

[Davidasailor26]

My concern with chain would be that given its shape the amount of cross sectional area you're actually providing to carry the current is very small. The contact surface between chain and mast, or between individual links is not nearly enough to carry the tens of thousands of amps of a strike. Bonding the rig to the keel provides a much better (albeit still often inadequate) path.

As for the EMP device - I've never looked into it, but it looks like it sits on the 12V power line and claims to absorb surges there? If so, I'm skeptical that it would do anything about lightning coming in from VHF antennas or NMEA wiring that's not the 12V circuit itself.

 

[nfg2u]

I was looking at the EMP Shield for Vehicles.. but its $340.00. I just ordered a couple of uxcell LRSO1 DC 12V Lightning Arrester Power Surge Protector from Amazon. I plan to put them on the power side of my Raymarine Backbone. They are 14.00 a piece. Might not work but at least there is some protection there. The claim "Used to protect the coaxial data transmission of communication circuit system, repeater, switchboard devices.". At least I have done something. Last time I got hit by lighting my chart plotter was ok, but the network side of the chart plotter stopped working.

 

[JohnShannon]

try to park your boat next to a boat with a taller mast

 

[JamesG161]

The key to any reduction in strike potential is a well grounded Boat.
Most Hunter's are designed with that in mind.

If a strike is nearby...
With Shore Power connected...

The reference Ground will increase rapidly
AC white or Green wire will not be Zero anymore and will increase.
______
Shore Power disconnected...

The Water will not be Zero reference anymore.
The Boat overall Grounding system will increase in voltage.

_____
How do you stop the Reverse Voltage on your boat?
Nothing I know of....

But what about surges protecters?
Depends on Volts and Amp or Power.

Look on the spec sheet for WATTS stopped.
Jim...

 

[JamesG161]

I actually do something similar. I have a few links of chain with a snap hook that I clip to the shrouds and toss over the side when I’m anchored out and a storm pops up. I can’t say that it works or not

That is a method of grounding your boat.
Jim...

 

[JamesG161]

@rgranger
Add this plate or bigger to that chain when tossed overboard.
Guest Dynaplate Standard Grounding Plate

 

[JamesG161]

Also this can reduce charge build up on your boat when on the water.
Forespar Lightning Master Static Dissipator

 

[capta]

The one system that seemed a possible solution actually seemed to attract lightning strikes on the test boat it was installed on. They had two strikes in less than a couple of weeks and the system did not completely protect the boat anyway!
I can't see adding anything to the shrouds would actually work as a strike is mega power and would probably still do lots of damage like burning the chain plate right off the hull. I know a lot of folks do it, but I've seen no stats on it's effectiveness.
I had one strike hit the boat across the dock from me in the Keys and the bolt came through the shore power and took out all the equipment that wasn't running, go figure! The fridge, the A/C unit, the battery charger and a few other systems that were in use were fine, but the A/C unit that was off got trashed. The electronics survived.
I think it's a total fallacy that a taller mast will protect you as I've been offshore in numerous lightning storms and my mast was definitely the tallest thing around, but did not got hit on one boat, yet on other boats I have.
I'd say your only defense if your boat is one of those that attracts lightning strikes is to completely undo all electrical and electronic equipment each time you leave the boat or get a really good insurance policy.
Good luck.

 

[JamesG161]

the bolt came through the shore power

Typical back flow of a strike while in berth with shore power connected.

But if your boat is well grounded then there can be a Faraday Cage effect.
Microwave ovens have one and do protect.

Not prevention, just reducing you chances of being hit.

Why do Water Towers and Bridges seem immune?

Answer: Well grounded.
Jim...

 

[nfg2u]

Grounding.. I wonder why they don't have a grounding point on the dock that boaters could connect to not unlike a plane while fueling.. Connect the ground wire from the boat to a "known" ground on the dock. May be I have new business idea.

 

[rgranger]

Grounding.. I wonder why they don't have a grounding point on the dock that boaters could connect to not unlike a plane while fueling.. Connect the ground wire from the boat to a "known" ground on the dock. May be I have new business idea.

Gheeeze.... you better patent that quick.

 

[walt]

For the OP and back to your original question.. You probably know that the lightning bolt traveling through a mast or just in the air creates a large magnetic field. Any conductor that has at least some orientation parallel to the direction of the lightning charge flow will react with that magnetic field and it creates current in that wire. Ie, the lightning current flow in a boat next to you can create a large magnetic field that couples with wires in your boat inducing current that can damage things (based on your post, I think you may have known this already). FYI, it wont matter if your boat is "grounded" or not or if you have the fuzzy contraption on top for the magnetic coupling to create current on the wires in your boat.

Any wire on the boat can pick up that magnetic field and produce surge current. That wire could be a 12 volt supply line or data line or it could be a circuit trace inside of some electronic box.

Circuit trace "wires" inside electronics.. nothing you can do, just hope the manufacture worried about this at least a little.

The device in your initial post was for protecting data lines and probably a good idea as the receiving end for data is going to be a sensitive circuit and easier to damage.

I used to be involved with consumer electronics and we would put a surge protection TVS type diode on any input that could couple in surge voltage/ current. I can no longer find the part that we used but the closest I found was something like this

Amazon.com: (5PCS) MR2535L DIODE TVS Surge 6A 20V AXIAL 2535 MR2535 : Electronics

Buy (5PCS) MR2535L DIODE TVS Surge 6A 20V AXIAL 2535 MR2535: Surge Protectors - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

The ones I was familiar with had to pass a lightning surge test that was honed over time to reduce field returns. But.. cant find that part. I think it had a 3K watt transient spec and I could not find that for the part in the link above.

But.. I would suspect that you could install two of these diodes in parallel from the link above right at the 12 volt DC power input of any device you were worried about. Data lines or RF signal lines are more complicated and you can not just stick a diode on each line to ground. But.. I think the TVS diode might help for the EMP issue you were asking about on 12 volt power line runs. You of course have to connect up the diode correctly polarity wise.

Cant guarantee any results but a lot of this is just reducing the odds and I think surge protection on all wires would reduce the odds of damage.

 

[capta]

Grounding.. I wonder why they don't have a grounding point on the dock that boaters could connect to not unlike a plane while fueling.. Connect the ground wire from the boat to a "known" ground on the dock. May be I have new business idea.

Considering the power in a lightning strike and the likelihood that should that come to a fitting on a dock which probably couldn't handle that much power, then the chances are the dock would become the casualty point. I just don't see how a dock fitting could handle that much power.
I've seen holes blown in the bottom of boats when the lightning chose to go straight rather than seek out some grounding wire and chain plates ripped off a boat, etc.

 

[Tally Ho]

try to park your boat next to a boat with a taller mast

I was chatting with a powerboat owner the other day after a big T-storm that knocked power out at the marina for about 12 hours....he laughed about not being worried about his boat being struck by lightening....he has a Hunter 33 on one side, and a Hunter 40 on the other! He figures he is in a safe spot.

Greg

 

[Davidasailor26]

I was chatting with a powerboat owner the other day after a big T-storm that knocked power out at the marina for about 12 hours....he laughed about not being worried about his boat being struck by lightening....he has a Hunter 33 on one side, and a Hunter 40 on the other! He figures he is in a safe spot.

Greg

Unfortunately if one of those boats adjacent to him gets hit he's probably going to have some damage as well. A long time ago I was in a marina with powerboats next to sailboats. One of the sailboats got hit, and a couple of the nearby powerboats had damage. The powerboats became a bit resentful of the tall sailboat mast for "attracting" the lightning that did the damage.

 

[Chris Patterson]

A few years ago, lightning dodged everything in the marina to hit a flat bottom Jon boat sitting in the corner.

As Archie Bunker used to say to Edith, “Nobody knows”..

 

[JamesG161]

I've seen holes blown in the bottom of boats when the lightning chose to go straight rather than seek out some grounding wire and chain plates ripped off a boat, etc.

This is what happens on a Direct Strike.

When boats get lightning damage, it is quite variable.

Example: If a small, Direct strike hits near the marina power Supply area and its Grounding Rod.
1)10,000 Volts Strike Hits and all that power has to dissipate rapidly.
2) Since the soil is moist, the Voltage drops rapidly, so about 100 feet away from Strike, it is now 600 Volts. Not Zero ground.
3) The Power Ground rod happens to be at 100 feet from the strike.

oops...

4) The Green wire and White wire of the 120VAC power system are Grounded by that rod.

Rut roh...
Your boat is plugged into shore power.
White and Green wire are NOW 600 Volts

What can happen to your boat?

This is my old Shore Power boat input. White wire is Charred, along with my cord.
But Two 30Amp breaker on my boat Tripped, luckily before significant damage.

I replaced All of that line, circuit breakers etc. $600
I have two 30 Amp shore power lines.
Why not both? Ans: Nothing running on the other.

Moral to the story...
1) My 67' foot mast is well grounded in the water. No strike.
2) Shore power area does not have Lightning protection.... only exception is near its Fuel Tanks.

Jim...