Lightning Protection Wires to Keel Bolts

[Richandhelen]

While replacing my sticking primary bilge pump float switch I found that BOTH of my lightning protection wires had separated from their keel bolt attachment. It's a poor design as the bilge always has some water in it - the condensation from the A/C units empties there - to be emptied by the bilge pump as the level rises. So the attachment points are always under (fresh) water. The TOPS of the keel bolts are nearly always above this level, however. They are dry. Keel bolts are withstanding this constant immersion BTW.

Two questions:

Is there a way to get a routing for the A/C condensation so I can keep the bilge DRY?
If I have to keep what I have, what is a good way to attach the lightening wires to the keel bolts above the water level?

Thanks!!

 

[ice breaker]

Check this link from last year.

http://forums.hunter.sailboatowners.com/showthread.php?p=1135781&highlight=mazzei

 

[ice breaker]

here is another link.

http://forums.hunter.sailboatowners.com/showthread.php?p=1029245&highlight=mazzei

 

[Don S/V ILLusion]

If residual water in you bilge is the problem, why not fix that first?

In addition to creating an additional source of moisture in the boat, water in the bilge can cause other problems. It's a simple fix to install a Venturi on the A/C exhaust water to eliminate condensate from entering the bilge and you don't need an expensive commercially available kit do it.

As to lightning protection, if the wires pictured are your ground, the size is inadequate.

Eliminate the condensate so you have a dry bilge (which should be the goal) and run 0/0 wire to the bolts.

 

[Richandhelen]

If residual water in you bilge is the problem, why not fix that first?

In addition to creating an additional source of moisture in the boat, water in the bilge can cause other problems. It's a simple fix to install a Venturi on the A/C exhaust water to eliminate condensate from entering the bilge and you don't need an expensive commercially available kit do it.

As to lightning protection, if the wires pictured are your ground, the size is inadequate.

Eliminate the condensate so you have a dry bilge (which should be the goal) and run 0/0 wire to the bolts.[/QUOT

Thanks. Could you please give me the "Idiot's Guide" to what an exhaust venturi IS and how it operates?

The ground wires are about 1/4" in diameter and are not pictured.

 

[dehler25]

Would it not be easier to route the condensate to the shower sump?

 

[Don S/V ILLusion]

Could you please give me the "Idiot's Guide" to what an exhaust venturi IS and how it operates?

http://www.ehow.com/how_12103349_make-venturi.html

Lots of info if you try a google search too.

Most hardware stores or water bed stores carry cheap venturi tubes. Essentially, all you need do is 'T' it into the A/C exhaust line and the condensate gets pulled out the same thruhull eliminating the bilge water issues.

There are a few commercially available kits as well, most charging a ridiculous amount for what you can buy off the shelf and complete in a 1 hour project.

 

[Richandhelen]

Would it not be easier to route the condensate to the shower sump?

I like that idea. There is a shower sump in proximity to each A/C unit - forward and aft. Each sump is a closed box with a fresh water line from each shower pan. So I have to put in a plastic "tee" fitting before the box if I want to drain the A/C there as well? Is that correct?

 

[Don S/V ILLusion]

I like that idea. There is a shower sump in proximity to each A/C unit - forward and aft. Each sump is a closed box with a fresh water line from each shower pan. So I have to put in a plastic "tee" fitting before the box if I want to drain the A/C there as well? Is that correct?

Seems like this would result in moving condensate water from one place in the boat (the bilge) to another place inside the boat (shower sump) for the same effort as would be required to T a Venturi into the A/C discharge which would actually eliminate the water.

 

[Bill Roosa]

You might want to consider keeping the ligntnig out of the cabin in the first place. The insurance folks will tell you that most lightning strikes exit the boat at or near the water line. This is because when a charged cloud passes overhead it induces an opposite charge on the surface (top 1/8") of the water. Grounding to the keel (4+ feet under the charged surface) in not the greatest idea as the charge has to go down through the charged layer, through the keel and then back up to the surface. Lightening will probably not follow that route.
take a set of cheap auto battery jumper cables. Cut each in half and use the clamp to attach to the forestay, port and starboard shrouds and back stay. strip the cut end bear so it will expose the metal cable at the water line and throw it over the gunnel.
This is in line with how engineers lightening protect buildings.

 

[KD3PC]

lightning is going to go to "ground" the shortest, fastest path it can find. A pair of battery cables and the associated clamps are going to present a great deal of resistance no matter the design or placement.

Resistance slows or eliminates paths to ground. There is no guarantee that the shrouds are electrically identical to the mast or the forward/backward stay - therefor the lightning may jump to one of them or another nearby boat before discharging to ground.

A complete faraday cage will work, but not practical or economically ideal. The rest of the protections are mostly marketing, as NOTHING will prevent a strike.

http://nasdonline.org/document/209/d000007/boating-lightning-protection.html and studies from the FL Sea Grant are more accepted.

 

[CoolChange91-42passage]

It's amazing to me how much people don't understand about lightning. The idea is to prevent the strike not to route it, which is impossible. You prevent it by equalizing the potential difference between the sky and the area the boat occupies on the water. The boat is just a shorter distance for the Lightning to travel through the air which means it is the least resistive path to ground. The way to prevent the sudden release of static electricity through the boat is to continually bleed off the static charge into the sky from the spot you are protecting. This is accomplished by grounding the mast to the water, hence the bonding to the keel that everyone speaks about. Occasionally, all the bonding in the world is not enough to keep up with the buildup of static. It requires extra things such as static dissipaters, fuzzy wire brushes mounted on the top of the mast, or cables from the shrouds directly into the water. Because the bonding is usually in highly corrodible places, it is not always dependable requiring some extra measures. If anyone actually thinks they can control the path of a lighting strike they are delusional, that's impossible. You need to be the best grounded boat in the area when a storm comes through. If you are, you will be spared and one of the others near you will pay the price. I got hit twice in one week, added the dissipater and the jumpers into the water. Never again!