Hobie 18 comptip w/squaretop and Nacra I17 spin setup - want to stiffen the comptip until I can find and all alu H18 mast.

I'm thinking to sand to the glass fibers, then tightly wrap in maybe 2 layers of thin glass.
Technically, I'm not sure how; maybe:

- Remove sail track, get lightweight glass, tape off the lips the track goes into, and glass it. Come back when glass is half setup and trim the excess away so the sailtrack will snap back on. ??

- will the comptip then flex as one unit, or will the new glass take all the load first, crack, then the comptip takes the load..?

Am I making this diffucult? Looking for discussion/advice.... thx,
Rob.

http://www.osyc.com/index…ontent&func=view&pid=22

what is the failure component or location of concern? - the comp tip body; the connection to the mast?

what is the failure mode of concern? breakage, excessive bend but no breakage?

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Ted
Hobie 16
South Carolina Lake sailing
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Hi,
I'm concerned about the comptip failing (breakage), either at the connection to the mast or between it and the spinnaker bail line. (spin mast hound is in w/6 rivets, connected to it is a 6 or 8 in drop line to the spinnaker halyard block. That block is tied around the comptip (along the back though a hole in the luff track). The mast stress is between this bail line and the mast connection.

I'd like to stiffen the whole thing up a bit anyway because downhaul bends the tip rather than pulling on the sail...

If you want to stiffen up the comptip, you need to use carbon fiber. Unidirectional carbon tape run lengthwise along the mast would probably be best. Two plys of glass (6oz??) would have no appreciable impact on mast stiffness. It's hard to say how many plys of carbon you should use, I would guess three plys would be a good starting point. Perhaps you could take some stiffness/deflection measurements using the mainsheet before and after to measure the change in stiffness.

Anyway, to laminate the carbon, I'd first scuff up the mast and wipe with acetone. Then mask off the luff track. Then paint on a thin layer of epoxy, lay on the carbon (cut the carbon to fit first, don't trim afterwards, you can make a paper template), wet out the carbon thoroughly between layers, then use electrical tape to wrap the full length of the comptip. Leave about 1/32" gap between the tape wraps. This will compress the carbon against the mast and allow excess epoxy to squeeze out. After the epoxy fully cures, you can remove the tape. Clean off the adhesive residue with acetone, lightly sand if necessary, and paint.

Keep in mind that this won't make the comptip joint any stronger, but it should make the comptip itself stiffer.

sm



Edited by Dogboy on Jan 05, 2013 - 03:11 PM.

What about just adding an Aluminum tip to the mast you have A mast or boom section may be easier to find than a whole mast. Slice sleeve and weld - semi instant all aluminum mast!!

If I was going to stiffen what is there I would - Oh Hell I would do the above or get another mast Sail it til it breaks!!!

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Lee - On the BIG Lake in MS

Harstil Kaulua 31 - Current Project Boat
Cal 25 - What ? Time to freshen it up again??
MC Scow 16 (1 in the water and 1 parts/project) SOLD
Capri 22 - What do you mean you wont deliver it??
Chrysler Pirateer 13 - new addition to the fleet
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Thanks for the inputs... I'm still looking for a solid alu mast and may do a carbon wrap in the mean time...