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Carbon fiber a comptip? #50238
06/01/05 04:45 PM
06/01/05 04:45 PM
Joined: Apr 2002
Posts: 195
White Bear Lake, MN
h17racer Offline OP
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h17racer  Offline OP
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White Bear Lake, MN
Interested to find out if anybody has looked into or actually done this.

I have Hobie 17 with the usual bendy tapered comptip. A square top sail puts more power at the top of the mast but also introduces an element of overbend.

Anyway, interested to hear what others have experienced.

Sail fast, Tom G

-- Have You Seen This? --
Re: Carbon fiber a comptip? [Re: h17racer] #50239
06/06/05 09:50 AM
06/06/05 09:50 AM
Joined: Jun 2001
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Houston
carlbohannon Offline
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Houston
I thought about this once so I will take a stab

It would be tough

If you just added a stiff uniform carbon skin, the skin would be stiffer and would take all the load until it cracked/broke.

If you add enough carbon, to take the load, the old comptip is useless weight

A nonuniform reinforcement, basically a flexible mast that would take part of the load, would be tough to design.

If I were doing it, I would either

vacuum bag thin (2-4 oz?)glass to the outside

add an existing mast (windsurfer tip) to the inside as a sleeve. Attaching it at the metal mast joint, top of the comptip, and any hounds. This transfers bending as compression to the metal mast.

I guess what I am saying, you can do it but it will not be easy.

Re: Carbon fiber a comptip? [Re: carlbohannon] #50240
06/06/05 09:57 AM
06/06/05 09:57 AM
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MI
sail6000 Offline
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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 Offline
Carpal Tunnel
Mary  Offline
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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 Offline
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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: Jake] #50243
06/06/05 11:25 AM
06/06/05 11:25 AM
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Key Largo, FL & Put-in-Bay, OH...
Mary Offline
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Doesn't matter, Jake. If he puts carbon on his comptip, he is basically eliminating the entire purpose of the comptip as far as the company, the class and the insurance company are concerned.

Re: Carbon fiber a comptip? [Re: Mary] #50244
06/06/05 12:27 PM
06/06/05 12:27 PM
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MauganN20 Offline
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....which no other sailboat manufacturer has to adhere to.

Re: Carbon fiber a comptip? [Re: MauganN20] #50245
06/06/05 12:49 PM
06/06/05 12:49 PM
Joined: Nov 2002
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Key Largo, FL & Put-in-Bay, OH...
Mary Offline
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Quote
....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: Mary] #50246
06/06/05 06:42 PM
06/06/05 06:42 PM
Joined: Apr 2002
Posts: 195
White Bear Lake, MN
h17racer Offline OP
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White Bear Lake, MN
Jake hit the nail on the head. Only interested in hearing others point of view when a comptip (or any mast) is too bendy for a square top sail. I already race open with an H17 so modifying an existing mast could be done.

As Maughn17 mentioned Hobie is the only manufacturer that uses a comptip. As I recall that was a result of litigation. That addressed a symptom. The problem was with power lines too low at launching areas. I do not believe that problem has yet been resolved nationwide

Anyone hear of a mast coming in contact with a power line recently?

Sail on, Tom G

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 Offline
Carpal Tunnel
Jake  Offline
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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] #50248
06/06/05 08:17 PM
06/06/05 08:17 PM
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MauganN20 Offline
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It happened to one of the JY's in the club two years back. Luckily the boat was being moved around a campsite on a trailer with the mast up. It hit the lines and bang snap.

And Mary, my point about mentioning the fact that Hobie is the only one that makes "comp tips" is the fact that if electrical insulation was such a big issue that he would need to bear in mind to preserve that property whilst making his modifications.... numerous other manufacturers would be producting non-conductive masts. However, they aren't, because they realize (as does hobie I'm sure) that the increased performance is more important to the customer base than protection from powerlines.

I mean who goes into the showroom to hear the salesman say: "yes we incorporated this comptip on the top of the mast so we can save you from your own stupidity when raising the mast around powerlines. That'll be $11,000 Please."

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 Offline
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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 Offline
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Jake  Offline
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Quote
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
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Posts: 833
St. Louis, MO,
Mike Hill Offline
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Mike Hill  Offline
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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: Mike Hill] #50252
06/07/05 11:22 AM
06/07/05 11:22 AM
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Posts: 975
South Louisiana, USA
Clayton Offline
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South Louisiana, USA
A friend dropped his Stiletto mast when the forestay came in contact with a power line. For the uninitiated, a Stiletto mast is 36' (Standard) and weighs as much as some of the lighter cats out there. When that comes down you don't want to be in the way. Luckily no one got hurt but I think that mistake cost about 3 to 4K to correct. Always look up, especially in an area you're not used to.

Clayton
S-27

Re: Carbon fiber a comptip? [Re: Clayton] #50253
06/07/05 01:18 PM
06/07/05 01:18 PM
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Gainesville, FL 32607 USA
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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.com

He 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: dacarls] #50254
06/07/05 01:33 PM
06/07/05 01:33 PM
Joined: Nov 2002
Posts: 606
League City, TX
flumpmaster Offline
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League City, TX
OSYC, July 2004 - we saw a Hobie 20 that had been struck by lightning on the comp tip. The only cat with a comp tip on the beach (amongst over 20 other cats). The comptip was peeled open like a banana. You could see where the arc jumped from the mast down to the front cross bar, back through the port hull before emerging through the side of the hull to the trailer side roller. Completly burnt through the hull - not pretty.


Dave Ingram is my president. tcdyc rules
Re: Carbon fiber a comptip? [Re: flumpmaster] #50255
06/07/05 06:22 PM
06/07/05 06:22 PM
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Posts: 1,658
Florida Suncoast, Dunedin Caus...
catman Offline
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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: catman] #50256
06/07/05 08:28 PM
06/07/05 08:28 PM
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Posts: 390
samevans Offline
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Sorry Mike ,but your "Big Brother" paranoia is not warranted.
The fact that the Hobie comp-tip was the result of a negotiated settlement of a lawsuit is well established.
Of course Hobie Corp, in their infinite marketing wisdom, describes the damn thing as a performance enhancement.

There was a similar (operator error) lawsuit against Nacra.
They chose to fight it and won.


About the original question.

You might be able to take a piece of a broken carbon mast, that matched the section, and make a comp-tip out of it.

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
J
Jimbo Offline
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Quote
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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