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 Post subject: Can I repair a comp tip?
PostPosted: Sun Aug 26, 2012 8:16 pm 
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My Getaway was overturned on the beach in some strong winds last week. The mast bob and mast head were both detached from the comp tip as a result. Part of the mast head is still seated in the comp tip (with the rivets that hold the halyard clip...not sure what that's called) so I'm definitely in need of a new mast head. The bob is fine but the top of the comp tip is cracked. There were two rivets that held the mast head in place which were pulled out. The holes for those rivets are now slots which obviously extend to the end of the comp tip.

I'm no expert on composites and am wondering what the "composite" tip is actually constructed from? Is it just fiberglass or is it something more than that?

Whatever it is, can I fix it by fiberglassing the end? The damage only extends about 2".

Thanks very much in advance.

Randy


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PostPosted: Wed Aug 29, 2012 5:43 am 
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It is just fiberglass using vinylester (polyester) resin. You can do repairs using similar material or epoxies.

We call the fitting a halyard "hook".

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PostPosted: Wed Aug 29, 2012 9:09 am 
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I did a similar repair on my H18 comptip earlier this year which I'll try to describe.  I had some water in my comptip at the beginning of this season, and when I removed the mast head to get the water out, I cracked the top couple inches of my comptip (the head cap was glued in and the front of the comptip is very thin up top).   

I used carbon fiber, fiberglass, and epoxy resin (all materials ordered from uscomposites.com).  I used carbon fiber because it is much stronger than fiberglass and I wanted this repair to be strong enough to support the mainsheet/downhaul loads.  Repair patches were applied both inside and outside the mast. 

Image

The first step after removing the mast head is to sand/clean the repair surfaces really well.  My repair patches were about 4" long, so it was necessary to prep the surfaces at least 4" down the mast.  After the surfaces were really well cleaned and scuffed up, I wiped with acetone (after wiping with acetone, do not touch with your bare hands otherwise you'll contaminate the surface).   

Image

For the inside patches, I applied two layers of 6 OZ carbon fiber tape with one layer of fiberglass.  The purpose of the fiberglass layer is to provide an insulation barrier between the carbon fiber and the aluminum head cap to prevent galvanic corrosion.  I wet out the carbon/fiberglass on a sheet of cardboard first and then placed inside the mast and smoothed out with a brush.  After it cured, excess material was trimmed off. 

Image

For the outside repair, I used three layers of 6 OZ carbon fiber.  Before laminating the repair patches, I masked off the luff track to prevent resin from getting on it.  After the repair patches were in place, I wrapped them firmly using electrical tape.  Doing this compresses the patches against the mast and squeezes out excess resin (much like vacuum bagging).  Once the epoxy cured, I removed the tape, wiped with acetone to remove tape residue, and lightly sanded. 

Image

Image

For the final step, I took some glass roving tows (basically a large bundel of glass fibers), saturated them in resin, and wrapped around the very tip of the mast several times in order to provide immense "hoop strength" to prevent the tip of the mast from spreading open.  I also overcoated the entire repair in epoxy resin.  (Still haven't gotten around to finish sanding).

Image

Last, I re-installed the mast head and halyard hook. 

Hope this helps.

sm       


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PostPosted: Wed Aug 29, 2012 8:17 pm 
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Thank you very much for the reply and the time you've taken to explain things. I plan to do the repair this weekend.

Again, many thanks.

Randy


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PostPosted: Fri Aug 31, 2012 5:12 am 
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No problem. My recommendation if you haven't worked with composites before is to figure out how you're going to do everything BEFORE you start mixing resin. Do dry runs with paper templates or dry cloth. Also be sure to wear disposible latex gloves, safety glasses, and have plenty of cheap disposible brushes handy.

Good luck.

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PostPosted: Sat Jan 05, 2013 9:29 pm 
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It's that a normal Comptip? It does not seem to have much of a taper. Are there different comptip styles for the 18?

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PostPosted: Sun Jan 06, 2013 7:38 am 
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It's a tapered comptip. There is only one type of comptip for the 18.

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PostPosted: Sun Jan 06, 2013 8:34 pm 
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SRM, you could have blown up a balloon on the inside of the comptip to squeeze the layers similar to vacuum bagging. (just a thought).

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PostPosted: Tue Feb 26, 2013 2:49 am 
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srm wrote:
It's a tapered comptip. There is only one type of comptip for the 18.
sm

Agreed totally. The exclusiveness for the 18 is not good and is really terrible to know that there aren't any alternatives present.

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PostPosted: Tue Feb 26, 2013 10:08 am 
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donniepaxton wrote:
Agreed totally. The exclusiveness for the 18 is not good and is really terrible to know that there aren't any alternatives present.



:?: :?:

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PostPosted: Sun Mar 03, 2013 8:37 pm 
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donniepaxton wrote:
srm wrote:
It's a tapered comptip. There is only one type of comptip for the 18.
sm

Agreed totally. The exclusiveness for the 18 is not good and is really terrible to know that there aren't any alternatives present.

Spam?

Thanks, srm, for being a valuable addition to the Hobie community.


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