Lightning prevention system.

[garyfdl]

So in following this thread, reading others, and looking at the supporting 'data' (thanks Gord)...

It seems the prudent thing to do is:

• ground and bond the boat properly to hopefully withstand a strike.

• employ lightning prevention measures (Lightning Master etc.) and hopefully they will work.

[s/v Jedi]

Originally Posted by garyfdl

So in following this thread, reading others, and looking at the supporting 'data' (thanks Gord)...

It seems the prudent thing to do is:

• ground and bond the boat properly to hopefully withstand a strike.

• employ lightning prevention measures (Lightning Master etc.) and hopefully they will work.

Yes and both can be done using the same parts/system.

Please note you need a special bonding plate for this: https://www.jamestowndistributors.co...t-detail/13331

The 6AWG cable from the base of the mast to this plate must have no sharp bends and always keep going downwards to the plate.

Edit: also, do not connect any electrical wiring to this. No DC negative, no AC ground, no AC Neutral, nothing, just the base of the mast and other metal parts that stick up above the deck.

Also, if you have two masts then you need two of these plates.

[team karst]

Strong evidence to suggest bonding plate to be at or just ABOVE waterline.

That evidence being holes blown thru plastic hulls at waterline despite good keel attachment.

[s/v Jedi]

Originally Posted by team karst

Strong evidence to suggest bonding plate to be at or just ABOVE waterline.

That evidence being holes blown thru plastic hulls at waterline despite good keel attachment.

No, please. Right under the base of the mast, straight connection between mast and bonding plate.

Boats with holes blown through fiberglass do not have these bonding plates to deal with lightning strikes. They are 100% effective in preventing that kind of damage when installed correctly.

[garyfdl]

Originally Posted by s/v Jedi

Yes and both can be done using the same parts/system.

Please note you need a special bonding plate for this: https://www.jamestowndistributors.co...t-detail/13331

The 6AWG cable from the base of the mast to this plate must have no sharp bends and always keep going downwards to the plate.

Edit: also, do not connect any electrical wiring to this. No DC negative, no AC ground, no AC Neutral, nothing, just the base of the mast and other metal parts that stick up above the deck.

Also, if you have two masts then you need two of these plates.

(New-to-me) boat already has a bonding plate, but I have no idea if it is still 'electrically' connected to anything (a continuty check is on the 'to-do' list) list. Also not sure it sufficient area-wise. Installing a new/additional plate on this boat may not even be possible. It has internal ballast which is concrete and cast iron. Pretty much un-drillable, especially for any distance.

The big concern/annoyance is I have a deck stepped mast. I haven't seen/noticed a ground wire for it, so will probably have to install one (which I just know will be a pita).

But 'ya gotta do what ya gotta do'...

[s/v Jedi]

Originally Posted by garyfdl

(New-to-me) boat already has a bonding plate, but I have no idea if it is still 'electrically' connected to anything (a continuty check is on the 'to-do' list) list. Also not sure it sufficient area-wise. Installing a new/additional plate on this boat may not even be possible. It has internal ballast which is concrete and cast iron. Pretty much un-drillable, especially for any distance.

The big concern/annoyance is I have a deck stepped mast. I haven't seen/noticed a ground wire for it, so will probably have to install one (which I just know will be a pita).

But 'ya gotta do what ya gotta do'...

If it is a bonding plate to provide ground for SSB radio, then it is the wrong kind and can actually explode. The reason is that they maximize surface area contacting the water, like open asphalt, which is not suitable for high energy transfer. Water in the cavities of the plate can turn into steam blowing the plate apart.

There are no workarounds: it must be under the base of the mast and it must be the right kind of plate.

[team karst]

Originally Posted by s/v Jedi

Yes and both can be done using the same parts/system.

Please note you need a special bonding plate for this: https://www.jamestowndistributors.co...t-detail/13331

The 6AWG cable from the base of the mast to this plate must have no sharp bends and always keep going downwards to the plate.

Edit: also, do not connect any electrical wiring to this. No DC negative, no AC ground, no AC Neutral, nothing, just the base of the mast and other metal parts that stick up above the deck.

Also, if you have two masts then you need two of these plates.

We will disagree on this one. Also, dynaplates have been dismissed years ago as far as having an effective area increase.

[garyfdl]

Originally Posted by s/v Jedi

If it is a bonding plate to provide ground for SSB radio, then it is the wrong kind and can actually explode. The reason is that they maximize surface area contacting the water, like open asphalt, which is not suitable for high energy transfer. Water in the cavities of the plate can turn into steam blowing the plate apart.

There are no workarounds: it must be under the base of the mast and it must be the right kind of plate.

Boat is a Watkins 27 (27'). Not a blue water boat (IMO). So I kind of doubt that the plate was put in for SSB. But not sure if it is there for general grounding for the boat (would that make a difference?)

If I understand correctly, that the bonding plate has to be directly beneath the mast - presumably so that the conductor is straight, then I an screwed. Even though I could run a conductor straight down from the mast, I would then have to drill down through 3' of concrete and cast iron to get to the hull. Ain't happen'n. Best I could do is find the lead to the existing bonding plate and connect to that, trying to maitain the recommended (8") bend radius for the conductor (questionable if I can even do that do to space constraints).

I have had another 'brain fart'. I've thought of running a ground cable down/zip tied to the back stay, and then to a grounding plate under the stern. Cable would not enter the boat, and would be outside the hull the whole way. The biggest downside I can see is the ground cable would be in proximity to the helm.

[Frankly]

Copper like most other commodities has gotten kind of steep recently. I made this one from a copper plate from a company in Tennessee long time back. There are 4ea 1/2" silicon bronze bolts soldered to the plate all forming the conductive path. The soldering was to seal the interface between flat head bolt and the copper plate. Tried silver soldering but needed to be on the surface of the sun for that to work.

The IP has an internal keel but found the space just in front of the mast step. The hull just as close as possible to the mast base should also work.

My old Hunter had a deck stepped mast so Just ran the wire through the compression post. Connected one end to the mast and the other to the copper plate just aft of the compression post.

Anything that involves bilges in a boat needs to be checked on every once and a while.

[smj]

Originally Posted by s/v Jedi

Yes and both can be done using the same parts/system.

Please note you need a special bonding plate for this: https://www.jamestowndistributors.co...t-detail/13331

The 6AWG cable from the base of the mast to this plate must have no sharp bends and always keep going downwards to the plate.

Edit: also, do not connect any electrical wiring to this. No DC negative, no AC ground, no AC Neutral, nothing, just the base of the mast and other metal parts that stick up above the deck.

Also, if you have two masts then you need two of these plates.

So on a catamaran would it be good practice to run the cable from the LM through the bridgedeck and directly into the water?

[s/v Jedi]

Originally Posted by smj

So on a catamaran would it be good practice to run the cable from the LM through the bridgedeck and directly into the water?

I have heard several ways they do something like that but I simply don’t have the detailed knowledge. I’m sure there’s cat owners here who can tell more about it.

[GordMay]

Originally Posted by team karst

Strong evidence to suggest bonding plate to be at or just ABOVE waterline.

That evidence being holes blown thru plastic hulls at waterline despite good keel attachment.

Indeed.
At least one lightning expert, Dr. Ewen Thomson, of, advocates such.

”... lightning conductors should be placed at the locations where lightning damage is frequently seen, that is, just above the waterline. Since then, our experiments to investigate the sparking mechanism have revealed that current flow in the form of spark channels propagates in the air just above the water surface and that the extent of these channels are much longer than might be expected ...
... Prof. Moore and colleagues at New Mexico Tech. explain [1] the origin in terms of charge that is induced on the surface of the water or ground in response to the charge on the lightning channel ...”

➥ Science & Technology

[1] “An Examination of Lightning-Strike-Grounding Physics” ~ by C. B. Moore, G. D. Aulich and William Rison (Langmuir Laboratory for Atmospheric Research, New Mexico Tech)
➥ http://www.lightningsafety.com/nlsi_lhm/Radials.pdf

See also ➥ Articles

[team karst]

Consider the electrical response to a strike on a vessel. The atmosphere had developed an unbalanced charge. Lets say a POS net charge, a huge deficit of electrons. That POS charge will draw from the water/ocean a similar excess of electrons to make a NEG charge at the surface and lessor charge with depth and horiz distance. The ocean being a fair conductor.

Oops, too much charge develops and the insulation breakdown in air is exceeded. Lightning happens, and lets say a boat gets caught in the middle.
A high percentage of the conductive elements of the boat are involved, and current flows. Connecting cloud and ocean surface. Notice i say surface. We will get back to that…

Lets say a “grounding” attempt is made to great big and heavy and conductive lead keel. What could be better? Turns out a lot. To get to that keel attach, the down conductor needs to prevent that bolt of lightning charge from reaching the water, before it reaches the keel. And, that down conductor is rapidly bringing up other metals in the boat to these extreme voltages. There is not usually enough insulation in the downconductor system to prevent a sideflash to ocean. If the hull gets in the way, well, that is just another insulator breakdown. And, if plastic, it will stay “broke down”.

No, it is far preferred to deliver these mega-currents to the most available, most direct path. Not deep internal in a plastic boat, but external, at or just above waterline.

[GordMay]

Originally Posted by team karst

Consider the electrical response to a strike on a vessel. The atmosphere had developed an unbalanced charge. Lets say a POS net charge, a huge deficit of electrons. That POS charge will draw from the water/ocean a similar excess of electrons to make a NEG charge at the surface and lessor charge with depth and horiz distance. The ocean being a fair conductor...

Rather, let's say that thunderclouds are negatively charged, at lower levels, and positively charged at higher elevations, resulting in a positive charge below, on the water.

[team karst]

Originally Posted by GordMay

Rather, let's say that thunderclouds are negatively charged, at lower levels, and positively charged at higher elevations, resulting in a positive charge below, on the water.

Sure. Lightning, being a bipolar beast. There is a down to up and a up to down characteristic too. Not seeing that as relevant, for now.

Some good land based examples too. Excellent evidence of horizontal current flow and damage from strikes. And, a number of proponents of land based current sinks that use conductors just slightly buried; being more effective than deeply driven grounding rods.