My brother brought Sprite (CD25) to my yard today and I began on my winter fixit list. One thing I planned to do, after a particularly electrically tropical summer here in NE, is to ensure I have proper bonding of the mast and stays for lightning protection.
As I looked at the mast step today, I realized that I have no idea how to attach the #4 or #6 wire to the mast step. It appears that the mast step is screwed directly into the steel support beam and there is not much thread left on those bolts to attach another nut and a lug.
Has anyone done this before and if so, what did you do? My check of the archives didn't turn up much.
Absent any better idea, I will attach a short length of wire inside the mast and add an additional connector in the cabintop. I do fear that, in the event of a lightning strike, any connector will simply evaporate.
Thanks,
Jeff
CD25 Mast Lightning Protection
Moderator: Jim Walsh
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Lightning Protection
Hi Jeff,
I don't know how much room you have to attach a lightning protection lug to the existing bolt. It might be possible to thread a coupling (coupler) onto the existing threads and attach the lug to the coupling with a suitable sized bolt.
If you only have two or three threads showing, find another method of attachment. This coupling is one of many links in the metallic "chain" which conducts a lightning strike from your mast tip to the ground discharge plate on the side of your hull, below water. Two or three threads , in my mind, doesn't provide enough contact area to sustain a lightning strike.
There is a very informative article on lightning and sailboats. It is written by Dr. Ewen M Thomsen, an engineer and formerly a professor at the University of Florida.
http://www.thomson.ece.ufl.edu/lightning/title.html
Scroll down and click Florida Sea Grant. After reading this very enlightening (no pun intended) article, you will have a much greater understanding of the awesome power and danger of lightning. You will also have knowledge on the best methods to protect your crew and boat from a direct strike.
If there is one thing that I would impress on your thoughts is that the copper wire sizes are minimums. It is okay to go up in size a little. Use an anti-oxide gel on all joints.
Good luck,
O J
I don't know how much room you have to attach a lightning protection lug to the existing bolt. It might be possible to thread a coupling (coupler) onto the existing threads and attach the lug to the coupling with a suitable sized bolt.
If you only have two or three threads showing, find another method of attachment. This coupling is one of many links in the metallic "chain" which conducts a lightning strike from your mast tip to the ground discharge plate on the side of your hull, below water. Two or three threads , in my mind, doesn't provide enough contact area to sustain a lightning strike.
There is a very informative article on lightning and sailboats. It is written by Dr. Ewen M Thomsen, an engineer and formerly a professor at the University of Florida.
http://www.thomson.ece.ufl.edu/lightning/title.html
Scroll down and click Florida Sea Grant. After reading this very enlightening (no pun intended) article, you will have a much greater understanding of the awesome power and danger of lightning. You will also have knowledge on the best methods to protect your crew and boat from a direct strike.
If there is one thing that I would impress on your thoughts is that the copper wire sizes are minimums. It is okay to go up in size a little. Use an anti-oxide gel on all joints.
Good luck,
O J
Try for the shortest path
Like O.J., I was very impressed with Ewen Thompson's work. On the other hand, I came away with the idea that there are no guarantees, especially with a deck-stepped mast.
My understanding is that the aluminum mast will conduct better than the stainless stays. If the mast is deck-stepped, though, with no straight path to ground, that means the energy may arc over to the stays.
This can be awful, since it just blows away anything in its path (I've seen photos that looked as if a bomb was dropped on the deck).
In order to reduce the likelihood of this, I believe you can provide an easier path to ground. This means "straighter and more conductive", so ideally, a honkin' big copper cable straight down to a plate directly underneath. Unfortunately, this would run right down the middle of the boat in a very awkward spot.
Or, you can adopt the attitude I did in a horrendous set of squalls this summer on Long Island Sound. Everywhere I looked, there were horrible purple explosions of lightning, all around. I decided that I was like an ant in the field, and that the farmer was walking around the field. I reckoned that if he stepped on me, well, that was it.
He never stepped on me, so I lived to tell the tale.
My understanding is that the aluminum mast will conduct better than the stainless stays. If the mast is deck-stepped, though, with no straight path to ground, that means the energy may arc over to the stays.
This can be awful, since it just blows away anything in its path (I've seen photos that looked as if a bomb was dropped on the deck).
In order to reduce the likelihood of this, I believe you can provide an easier path to ground. This means "straighter and more conductive", so ideally, a honkin' big copper cable straight down to a plate directly underneath. Unfortunately, this would run right down the middle of the boat in a very awkward spot.
Or, you can adopt the attitude I did in a horrendous set of squalls this summer on Long Island Sound. Everywhere I looked, there were horrible purple explosions of lightning, all around. I decided that I was like an ant in the field, and that the farmer was walking around the field. I reckoned that if he stepped on me, well, that was it.
He never stepped on me, so I lived to tell the tale.
static dissipator
The PO of my vessel installed a static dissipator at the masthead and I figured anything is better than nothing which is what I would have installed so I've left it there. I can attest that I have not been struck since owning the vessel so if I'm lucky it works perfectly, if I'm unlucky it's just sitting there aggravating a tern or a seagull, basically a win win situation. A previous boat I owned for eighteen years was sneak attacked by a bolt from a strike in the water just yards away during a sudden squall which hit at the south end of the Cape Cod Canal. My father was aboard at the time and the bolt fried the Westerbeke control panel, the VHF radio, and the LORAN which Micrologic was kind enough to replace for the price of the internal battery. We made out pretty well overall but, who knows, maybe a dissipator would have kept us intact.
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Sea Owl
- Posts: 176
- Joined: Sep 26th, '06, 22:38
- Location: S/V Sea Owl
CD25 Hull#438
Monmouth Beach, NJ
Grounding in CD25
Hmm...this leads to the interesting question of a grounding plate or some such on a CD25. I haven't found one on mine, and wonder if anyone else has such a thing?
I know the bigger CD's have them, usually near the keel.
Won't due much good to ground the mast to the cabin if there is no path to the water other than the stays/shrouds and hull!
Any thoughts?
I know the bigger CD's have them, usually near the keel.
Won't due much good to ground the mast to the cabin if there is no path to the water other than the stays/shrouds and hull!
Any thoughts?
Sea Owl
CDSOA Member #1144
CDSOA Member #1144
My plan was to install a small Dynaplate and run everything to there. I would have to mount the plate near the top of the keel where I could get access from inside.
Based on the article, I planned on #4 wire for the mast and #8 wire for the shrouds and stays. I would put the Dynaplate farily close to the mast (fore/aft) to minimize the length of the large wire. Conveniently, that also reduces the length of all the shroud lines also with only the stays having long runs.
Am I totally off track?
Based on the article, I planned on #4 wire for the mast and #8 wire for the shrouds and stays. I would put the Dynaplate farily close to the mast (fore/aft) to minimize the length of the large wire. Conveniently, that also reduces the length of all the shroud lines also with only the stays having long runs.
Am I totally off track?
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
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Shipscarver
- Posts: 173
- Joined: Sep 22nd, '08, 15:49
- Location: CD27
"SOUL MATE"
lightening plate
The wire connections to the plate in the bilge of my CD27 is coated with green corrosion. What is the best way to clean it?
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Green Coating
Shipscarver,
The green coating which forms on copper and its alloys is copper oxide. It is like a patina. It is the result of slow surface oxidation when copper is exposed to damp, moist conditions.
If you try to remove the oxidation, it will only reform again. It will do no harm when it forms on the long runs of copper. However, it shouldn't be allowed to form on the surfaces of copper at any junctions or tee taps. If you have mechanical connections at these junctures, I suggest that the connections be undone and any oxidation at the connection be wire brushed off. Try to get any green off of the sides or the surface strands as best that you can and brighten the copper.
Before remaking the connections, the copper at these joints should be coated with an antioxide paste. Try to brush the paste down and in between the outer wire strands.. It might be easier to use new "bug nuts" or U-clip connectors which you can get at electrical supply houses and home supplys and some hardware stores.
The connectors come in assorted sizes so if you decide to go new, bring the used clip with you to exchange for the correct size. The wire size range should be stamped on the side of the clip. Don't try to improvise. Only use approved bronze alloy clips and apply anti-ox to them, as well.
Good luck,
O J
The green coating which forms on copper and its alloys is copper oxide. It is like a patina. It is the result of slow surface oxidation when copper is exposed to damp, moist conditions.
If you try to remove the oxidation, it will only reform again. It will do no harm when it forms on the long runs of copper. However, it shouldn't be allowed to form on the surfaces of copper at any junctions or tee taps. If you have mechanical connections at these junctures, I suggest that the connections be undone and any oxidation at the connection be wire brushed off. Try to get any green off of the sides or the surface strands as best that you can and brighten the copper.
Before remaking the connections, the copper at these joints should be coated with an antioxide paste. Try to brush the paste down and in between the outer wire strands.. It might be easier to use new "bug nuts" or U-clip connectors which you can get at electrical supply houses and home supplys and some hardware stores.
The connectors come in assorted sizes so if you decide to go new, bring the used clip with you to exchange for the correct size. The wire size range should be stamped on the side of the clip. Don't try to improvise. Only use approved bronze alloy clips and apply anti-ox to them, as well.
Good luck,
O J
CD25 Mast Lightning Protection
How much protection is gained by running a hefty piece of copper wire from the mast, over the side and into the water?
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Larry DeMers
- Posts: 124
- Joined: Feb 5th, '05, 19:43
- Location: DeLaMer
CD30c #283
Lake Superior
Lightning Protection
To attach your heavy stranded cable from the couch-mounted tabernacle to the keel or other underwater feature, drill and tap a good 1/4-20 thread into the tabernacle at a convenient location.
Crimp and solder a metal terminal to your grounding wire (8 to 10AWG stranded, need not be insulated, since it does not matter), coat the connector and 1/4-20 bolt with anticorrosion grease and tighten it up well.
Route the ground wire to the very closest ground attachment point available, but as someone else wisely stated, keep *any* turns in the wire very gradual, and smooth, and not more than 30 deg. total overall. Lightning simply will not follow more turn than this, and will flash out to any nearby metal instead.
Use of a "grounding plate" is of questionable merit. Reason is experience with these plates as a lightning ground has shown that if the entire charge makes it's way to the plate, the extreme temperature can cause a steam explosion (remember that these plates have a billion little sintered nodules on their surfaces, in order to bring the boat into better contact with the water, through increase in the total surface area, which gave the boat a better RF Ground for LORAN and other sensitive electronics sytems of the 60's and 70's. This extreme grounding requirement was to help eliminate RF noise in your reciever). These little nodules then quickly overheat while dissipating the lightning charge, sometimes causing a large hole to be blown in the huill where the grounding plate was.
On my CD30, all underwater features are grounded together, so theoreticly the charge will go to ground in many parallel paths, splitting up the amperage so that one path doesn't take it all. In practice, lightning does what it wants anyway, so no gaurantees.
In 22 years of sailing Superior and all of it's T.S's, we have never even had a close call -on the boat. Now, walking to shore from the slip is another whole story.
Cheers,
Larry
Crimp and solder a metal terminal to your grounding wire (8 to 10AWG stranded, need not be insulated, since it does not matter), coat the connector and 1/4-20 bolt with anticorrosion grease and tighten it up well.
Route the ground wire to the very closest ground attachment point available, but as someone else wisely stated, keep *any* turns in the wire very gradual, and smooth, and not more than 30 deg. total overall. Lightning simply will not follow more turn than this, and will flash out to any nearby metal instead.
Use of a "grounding plate" is of questionable merit. Reason is experience with these plates as a lightning ground has shown that if the entire charge makes it's way to the plate, the extreme temperature can cause a steam explosion (remember that these plates have a billion little sintered nodules on their surfaces, in order to bring the boat into better contact with the water, through increase in the total surface area, which gave the boat a better RF Ground for LORAN and other sensitive electronics sytems of the 60's and 70's. This extreme grounding requirement was to help eliminate RF noise in your reciever). These little nodules then quickly overheat while dissipating the lightning charge, sometimes causing a large hole to be blown in the huill where the grounding plate was.
On my CD30, all underwater features are grounded together, so theoreticly the charge will go to ground in many parallel paths, splitting up the amperage so that one path doesn't take it all. In practice, lightning does what it wants anyway, so no gaurantees.
In 22 years of sailing Superior and all of it's T.S's, we have never even had a close call -on the boat. Now, walking to shore from the slip is another whole story.
Cheers,
Larry
Larry DeMers