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Old 04-12-2008, 20:20   #1
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Synthetic Rigging and Electrons

I am in the process of converting my 34' cutter rigged Searunner Trimaran over to be entirely synthetic's. In other words, all of my stay's, shroud's, backstay, the whole enchellada, will be Dynex Dux in place of SS wire. The tensioning will use deadeyes to replace the turnbuckles. I mention this fact as I think it might pertain to the questions I have. I can always post a photo or two if it will help.
Two questions:

#1...Lightning protection. I know there has been much good stuff posted of lightning protection. I have a centerboard trunk stepped mast which is also the floor of the center cockpit. It is aout two feet to the water directly below the mast. I see this as a really good path for lightning. My concern is is I have plastic (DUX is UHMWPE or ultra high molecular poly) Ropes holding up the mast. along comes a tropical downpour and the rig is soaked. If I get hit by lightning, will it conduct electricity? Or am I protected by a good path to ground? Don't forget I have deadeyes just above the deck. They consist of 4 turns of 3/16" Dynex. So...the only metal besides the mast, will be the aluminum eyes and "distributors"....they are spanned by the 3/16" Dynex. So no metal path on any of the rig.
#2.... I have found a way to bury a copper wire of the antennea size inside the Dux and I can use this for a side band radio on the backstay. I eliminate the need for any insulators and every thing is hunky dory.
However, what about that lightning? Will it heat up the copper wire? Also, I had someone tell me thought side band radios created heat when transmitting. Any one know? Would it be a low heat? Almost any heat applied over time would not be good on Dux. I mean 100 degrees is fine, but no 200 degree stuff.
Any how these oare some of questions as I get ready to stand up my mast with recycled plastic milk jugs for support....:-)
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Old 05-12-2008, 02:04   #2
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You should ask Dynex for the dielectric constant (conductivity).

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Old 05-12-2008, 06:25   #3
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Will do

Gord, thanks will do. Although that contact is a dealer I will contact the guys in Iceland to see what they say. I suspect this conductivity is a number? I will look it up some so I can understand what it is I am asking....:-)This will be interesting, I will post the results.

Anyone have any idea on whether or not a side band antenna creates any heat?

Jack
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Old 05-12-2008, 07:06   #4
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I'm not sure that the conductivity value of Dux will tell you what you want to know. It's fair to day it is very low. If it's wet it can carry a charge. Trees seem to do quite it well with a low conductivity. Your backstay antenna is as protected as well as any other antenna might be. If lightning can reach the ground it could surely induct your antenna encased inside any nonconductive cover you might imagine. As for being encased inside the Dux I'm not clear why you think there would be any advantage vs just attaching it to the Dux backstay. I'm not seeing where there would be a disadvantage either.

SS cable could easily be inducted while I doubt the Dux could be inducted. Wet Dux could carry a charge. The ability to quantify the lightning potential of the overall boat through the examination of the rigging material alone seems to be without merit. There really is no basis of evidence to suggest it has a significant basis for lightning protection given the inability to compute the risk of steel rigging alone. It might easily be argued that Dux is an improvement but the argument that it is significant would require a much more detailed study of the properties of lightning and any type of rigging. The converse argument might be made that steel rigging carries the charge along the outside of the vessel and offers the crew more protection since a direct hit to the mast might be deflected along the outside if the rigging was steel cables. It's an argument on both sides without end or evidence.

From the study I've done,the merit of using Dux as a rigging material is quite well founded. I expect you will be quite pleased with the boats rigging. The argument that it affords lightning protection is very weak. The ability to claim anything adds quantifiable increased lightning protection is for the most part weak. The greatest argument seems to follow that anything is better than nothing and with enough junk science you can make it sound good and thus believe greater protection is assured. Added confidence even unfounded may actually be an advantage. Wooden masts of old were often struck by lightning and suffered greatly I don't this that has changed with new materials.
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Old 05-12-2008, 07:26   #5
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Hot knife

Paul, Couple things. The idea of a copper wire buried in a Dux backstay is something I have not done yet. My concern is: Will it heat up when the radio is transmitting, and if so, how much? If it does I need to know the maximum and all that..... Second, on that same copper wire, if I was struck by lightning, would it heat up (and melt my backstay) by being conductive, am making a path for a hot wire to melt thru my backstay? Or if I ended the copper wire short of the top of the mast, would that be isulated? Does a ligntning strike produce heat (I suspect it does) Then if that is so, am I making a mistake to put a copper core in a dux backstay as far as lightning goes?
By the way I have a request from a friend to make two short sections of Dux with an eye on each end. This is what he wants to use as an insulator for his backstay. I suggested just replacing his backstay with a full length of dux and putting the copper antennae inside the rope. Hense the question now before I try this. Will it melt on a strike from lightning?
I was not looking to claim any sort of extra protection from using Dux, actually i was looking for the opposite. Am I at a disadvantage using Dux in a Hit from lightning? The concern is not whether in conducts a little or a lot I guess now that I think about it, as much as, will it heat up if this occurs. The heat would be the killer. You can cut this stuff with a hot knife quite well.
My contact in Iceland has already responded and is looking into if they have done any studies on tis stuff.
Paul thanks for you you time to post. I am looking fwd to a new rig, I just do not want any nagging doubts about the nasty stuff that can come along..:-)
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Old 05-12-2008, 07:42   #6
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A lightning strike thru an antenna will generate considerable heat, more than enough to melt synthetic rigging. The minimal thickness of the synthetic will not reduce the shock hazard to someone holding the stay while transmitting. Something on the order of a 1/2" separation is necessary, but you can use coax up the stay to a point out of reach before attaching to the antenna wire, just use a shroud that you can lose and keep the rig up.
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Old 05-12-2008, 09:00   #7
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Humm, never thought of the melting shroud thing. I am replacing our lifelines with Amsteel, maybe the rigging is next. However, our is a fractional rig, and I would like to add a SSB antenna at some point. My understanding is that losing any shroud on a fractional rigged boat is really really bad.

I could mount the antenna as a whip off of the arch. or???

Chris
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Old 05-12-2008, 09:07   #8
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O.K. here is what U got from Hampidjan I cannot copy and paste the info because it is in a PDF file. If anyone would like to read the who thing it is about 12 pages of info.

Figure 4:
Electrical properties

Resistance >10 to the 14th Ohm

Dielectric Strength 900 kV/cm

Dielectric constant (22 degrees C, 10 GHz) 2.25

Loss Tangent 2.10 to the power of -4

Melting point 144-152 degrees C

Thermal conductivity (along fiber axis) 20 W/mK

Resistance to alkalis....excellent

" " acids....excellent

'' '' most chemicals...excellent

"" "" to UV light........Very Good

So what does this tell you about my concerns of lightning? thanks....:-)
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Old 05-12-2008, 10:50   #9
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Quote:
So what does this tell you about my concerns of lightning?
It could melt, but I think you already knew that.

Quote:
I would like to add a SSB antenna at some point. My understanding is that losing any shroud on a fractional rigged boat is really really bad.
You can always lose a shroud, but you could always rig an emergency antenna since you could always lose the primary even not attached to a shroud.
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Old 06-12-2008, 03:24   #10
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If the Dielectric Strength* (insulating properties) DUX is 900 kilovolt/centimeter = 90,000,000 volt/meter; I would consider it an insulator, in most conventional applications.

I’m not competent to assess it’s lightning performance (extremely high voltage & frequency conditions when wet).

* Dielectric Strength is a measure of the electrical strength of a material as an insulator; defined as the maximum voltage required to produce a dielectric breakdown through the material and is expressed as Volts per unit thickness (usually Volts per meter). The higher the dielectric strength of a material the better its quality as an insulator.
Earlier, I confused Dielectric Strength with Dielectric Constant, which is the factor by which capacitance is increased when using that dielectric.


By way of comparison:
Air is 3 megavolt/meter = 3,000,000 volt/meter = 30 kilovolt/centimeter
Nylon is 14 megavolt/meter = 14,000,000 volt/meter = 140 kilovolt/centimeter
Bakelite is 24 megavolt/meter = 24000000 volt/meter = 240 kilovolt/centimeter
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Old 28-12-2009, 11:54   #11
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uh er, what did we we conclude? remember my eyes glaze when ya talk Dielectric Strength with Dielectric Constant...
What could happen if struck by lightning? Can it melt? I understand we cannot definitively predict, but rough estimate?
Thanks.
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Old 28-12-2009, 12:38   #12
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Originally Posted by Ocean Girl View Post
uh er, what did we we conclude? remember my eyes glaze when ya talk Dielectric Strength with Dielectric Constant...
What could happen if struck by lightning? Can it melt? I understand we cannot definitively predict, but rough estimate?
Thanks.
Erika
The short answer is it probably would melt, if you have a conducting wire either inside or alongside.

If it's just the rope, with no antenna wire, it is less clear but it probably would not melt. The lightening would probably go down the mast. It's possible but unlikely that you could have problems with the splices melting at the mast fittings if there was local arcing/heating
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Old 28-12-2009, 20:49   #13
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Even without a conducting wire within the synthetic shroud, it seems you might be in danger of losing the rig in a lightning strike. Any moisture in the shroud, enhanced by any ionic contaminants from the air, like salt, will increase the conductivity of that shroud, and lightning could choose to take the shroud as a path to ground, and perhaps destroy it. I would think the likelihood of this would be lowered significantly by making the mast a really really good path to ground. Unfortunately, lightning is very capricious and predicting exactly what it will do in a direct strike to the rig is a gamble.

I would really be curious to hear if there are any reports of synthetic rigged boats taking direct hits, and what kind of damage to the boat has been observed.
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Old 28-12-2009, 21:04   #14
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[QUOTE=SoonerSailor;380221]Even without a conducting wire within the synthetic shroud, it seems you might be in danger of losing the rig in a lightning strike. [/QUOTE

Whoops...wouldn't that be something. Zap, and the rig comes down. I have seen the damage done to a tree in my yard. Two foot around, split the trunk in two, then burrowed across the yard, set my pickups rear tire on fire, up into the frame to kill the electrical system forever...then split the 6 inch thick concrete cover over my well and fried the pump. Who here thinks they can calculate the power of something like that?
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Old 28-12-2009, 21:06   #15
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I would really be curious to hear if there are any reports of synthetic rigged boats taking direct hits, and what kind of damage to the boat has been observed.[/QUOTE]

I have not heard of any strikes, but as the numbers grow, I am sure we will. I am willing to be first.....I guess, it's pretty rare these days to be able to say you were the first at something

I found this today. This has been a while in coming. I know Brion Toss www.briontoss.com will not use wire for life lines anymore. If someone insists, he sends them to another rigger. This is nice they finally came around....:-)

Dyneema® fiber approved by ISAF council for use in sailing lifelinesUrmond,NL,07-Dec-2009Dyneema® fiber allows for greater safety and improves performance compared to traditional steel wire
During the annual ISAF (International Sailing Federation) conference in Busan, Korea, Dyneema® fiber was approved by the ISAF council to be used as a material for sailing lifelines, meeting rigorous standards yet increasing safety performance. The light weight and stronger lifelines with Dyneema® fiber are a technical advancement in yachting world.
The recent ISAF approval merely expands the permitted use of Dyneema® fiber in all other races and classes. Its use in the Melges 24 and Melges 32 classes for the past few years have already proven its effectiveness in these highly-competitive classes. Dyneema® fiber contributes to lighter, stronger and safer lifelines which are an important safety and performance feature on offshore and inshore sailing boats.
Bruno Finzi, Chairman of ORC (Offshore Racing Congress) and a member of the ISAF Committee, said: “I am happy to help in getting this measure passed. The ORC supports any such technical innovation that improves offshore sailing in both performance and safety.”
Marc Guillemot, skipper of the Safran race boat during the recent Vendée Globe race, said: “We used the lifelines during the last Vendée Globe for 25,000 miles. Lifelines made with Dyneema® fiber were very light and strong and their performance lasted in time.”
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