| Re: Carbon fiber a comptip?
[Re: carlbohannon]
#50240 06/06/05 09:57 AM 06/06/05 09:57 AM |
Joined: Jul 2001 Posts: 800 MI sail6000
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Posts: 800 MI | Hi Guys Yes -John Lindal here in Mich did this some 15 years ago on his winning 18 sq LCD . a C F top section mast on alum lower --epoxied in - John brought it out of storage and raced a few years back --the CF comptip still like new . Ian L his son is in San Diego and you might reach John through CRAM -Contacts - http://www.websitemagic.com/cram/ hope that helps Carl R | | | Re: Carbon fiber a comptip?
[Re: h17racer]
#50241 06/06/05 10:28 AM 06/06/05 10:28 AM |
Joined: Nov 2002 Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... Mary
Carpal Tunnel
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Carpal Tunnel
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Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... | If you replaced your Hobie 17 composite fiberglass tip with a carbon comptip, it would negate the purpose of the comptip, which is to keep people from getting electrocuted if their mast contacts an overhead powerline. Carbon, as I understand it, is an excellent conductor of electricity.
If you put a carbon tip on your mast, it would not be class legal. So if you are not going to race in class and are going to race in open class or not going to race at all, why not just get a whole new mast, designed properly for the boat?
Seems silly to have a two-part mast if you don't have to. | | | Re: Carbon fiber a comptip?
[Re: Mary]
#50242 06/06/05 10:41 AM 06/06/05 10:41 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | I think he's talking about simply applying carbon to his existing comptip to make it stiffer.
Most of the Hobie sails are shaped with the comp-tip in mind. Stiffening this will probably change the way the sail depowers.
Jake Kohl | | | Re: Carbon fiber a comptip?
[Re: MauganN20]
#50245 06/06/05 12:49 PM 06/06/05 12:49 PM |
Joined: Nov 2002 Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... Mary
Carpal Tunnel
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Carpal Tunnel
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Posts: 5,558 Key Largo, FL & Put-in-Bay, OH... | ....which no other sailboat manufacturer has to adhere to. That's irrelevant. It's just the way it is. If someone is not going to race their Hobie one-design, I cannot understand why they would want to keep a mast with a comptip if they have an alternative. And the comptip is already heavier than an equivalent section of aluminum mast, so why would you want to add even more weight to it just to stiffen it? More power but more weight at the top, so then you will soon be wishing the mast was bendier again to bleed off that power. The boat will capsize faster, and turtle faster, and be harder to right. Just get a whole new mast and be done with it. Or at least put a bob on the top. | | | Re: Carbon fiber a comptip?
[Re: h17racer]
#50247 06/06/05 08:07 PM 06/06/05 08:07 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
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Posts: 12,310 South Carolina | I heard of two last year - one in New England (no major injury except to the boat) and another in Key Largo ... I think the Key Largo incident was a construction worker who was moving a boat around at a resort and ended up loosing a hand. Or was that one more than a year ago? Mary?
It does happen and bitch and complain as we might about the comptip...there's no way to tell how many electrocutions have been avoided since nobody records 'near misses'.
With regard to modifying your existing mast, I would locate a similar profile from another boat (older/smaller Nacras come to mind) and modify the base casting and boom mount to work with the existing setup. Adhering carbon to the plastic comptip would have an unpredictable outcome. You could sleeve another piece of mast in place of the comptip but you will end up with a stiffer area at the point of the sleeve which might be worse with regard to performance.
Jake Kohl | | | Re: Carbon fiber a comptip?
[Re: h17racer]
#50249 06/06/05 10:23 PM 06/06/05 10:23 PM |
Joined: Jun 2001 Posts: 3,293 Long Beach, California John Williams
Carpal Tunnel
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Posts: 3,293 Long Beach, California | I got lucky - me and a very well-known and savvy skipper were sooooo focused on getting our boat back on the trailer and getting on the road a few years ago after Tradewinds, that we actually MOVED THE ORANGE CONES AND TAPE that were placed to indicate an overhead line (who put this %#@&! here??), and then we tracked right into it. It was a phone line, and we agreed to never speak to each other about it again. Its not just idiots... or maybe it is and there are more of us than you think. ps - Good luck with your project. Take pictures.
John Williams
- The harder you practice, the luckier you get - Gary Player, pro golfer
After watching Lionel Messi play, I realize I need to sail harder.
| | | Re: Carbon fiber a comptip?
[Re: John Williams]
#50250 06/07/05 06:15 AM 06/07/05 06:15 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
Carpal Tunnel
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Carpal Tunnel
Joined: Jun 2001
Posts: 12,310 South Carolina | Not a fan of it but, plastic comptip. I thought it was epoxy-glass lay up. I've had a few close run-ins myself where a comp-tip may almost have been useful. Fortunately, I realized what was getting ready to happen but only within inches. It can really happen to anyone in un-familiar territory. Sound Effect
Jake Kohl | | | Re: Carbon fiber a comptip?
[Re: Jake]
#50251 06/07/05 09:47 AM 06/07/05 09:47 AM |
Joined: Jun 2001 Posts: 833 St. Louis, MO, Mike Hill
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Posts: 833 St. Louis, MO, | It can happen to anyone. I know I've become so use to sailing at sailing clubs that I don't look up for powerlines anymore. The problem comes when I go somewhere that is not a sailing club. You really have to remind yourself to look up. I remember last year at Gilberts being very careful around some powerlines. It really is easy to forget because we are such creatures of habit. I never look up at my sailing club because I know there are no powerlines. This is a habit that is hard to break when you get away from the club. Mike Hill www.stlouiscats.com
Mike Hill N20 #1005
| | | Re: Carbon fiber a comptip?
[Re: Clayton]
#50253 06/07/05 01:18 PM 06/07/05 01:18 PM |
Joined: Apr 2002 Posts: 805 Gainesville, FL 32607 USA dacarls
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Posts: 805 Gainesville, FL 32607 USA | Dr. Ewen Thompson, formerly of the University of Florida Lightning Center has opinions about carbon masts. In his experience seeing them after lightning strikes is that they are NOT good conductors. He indicates that there is poor conductivity, particularly for the high voltage and huge ampere load, causing them to heat locally and basically explode. The result is not pretty. However the question is open in my mind- 1. You have an poorly conducting mast and or mast tip up in the air. 2. A possible alternative is a well conducting aluminum mast + heavy copper conductor + big copper plate grounded to salt water (the safest- Thompson would probably bet on that). 3. But if you have an aluminum mast with NO grounding to salt water- Where does a strike go then? "Other types of conductors need to be considered: Per the ABYC, a carbon fiber reinforced wood mast or a carbon fiber reinforced composite mast will not be treated as though it is a conductor." From "Lightning and Boats" website maintained by U. Florida as a public service since 1991. Dr. Thompson is now at ece@marinelightning.comHe told me that one experiment- "a copper wire carried by rocket into a charged cloud experiment to generate a strike" would only cost $200,000. Any takers?
Dacarls: A-class USA 196, USA 21, H18, H16 "Nothing that's any good works by itself. You got to make the damn thing work"- Thomas Edison
| | | Re: Carbon fiber a comptip?
[Re: flumpmaster]
#50255 06/07/05 06:22 PM 06/07/05 06:22 PM |
Joined: Jun 2002 Posts: 1,658 Florida Suncoast, Dunedin Caus... catman
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Pooh-Bah
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Posts: 1,658 Florida Suncoast, Dunedin Caus... | Maybe the comptip wasn't introduced to save us from our selves. Ever wonder why no other Co. used anything like it. Certianly people with prindles and nacras hit power lines. Could be Hobie benefited some other way by going to the comptip. Does the term U.S. grant money mean anything?
As far as the construction of it concerned, after drilling into it to install spin tang, seeing one busted in half and one blown up by lighting....It seems to be the same material the EPO's were made of. Not plastic. I'm of course talking about mast section not the track.
Have Fun
| | | Re: Carbon fiber a comptip?
[Re: dacarls]
#50257 06/07/05 08:37 PM 06/07/05 08:37 PM |
Joined: Jun 2005 Posts: 122 Jimbo
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Posts: 122 | Dr. Ewen Thompson, formerly of the University of Florida Lightning Center has opinions about carbon masts. In his experience seeing them after lightning strikes is that they are NOT good conductors. I have to concur. Of course carbon will conduct if the electrical pressure (voltage) is high enough. Most auto spark plug wires use fiberglass cords dipped in carbon dust for the conductor. As long as there are multi tens of thousands of volts, you get current flow. OTOH lightning has lots of voltage and current so instantly heats up carbon/epoxy to destruction. I work in aerospace and have repaired/refinished quite a few carbon fiber aircraft parts. I noticed that they always have so-called 'diverter' strips built in, just like fiberglass parts on airplanes. In this pic, the diverter strips can be seen as radial lines on the fiberglass nose radome: http://www.airliners.net/open.file/843505/M/ These are thin strips of copper bonded at or just below the surface at intervals along the surface. They are there to conduct lightning strikes back to metal structure. With airplanes, lightning strikes are not a remote possibility but inevitable. Sometimes an aircraft can be struck seveal times during one flight. If carbon conducted OK, they would not bother to use the diverters on carbon fiber parts. So it's not a conductor like a metal. Certainly not near as good a conductor as aluminum. Jimbo | | |
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