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PostPosted: Mon Feb 24, 2014 12:20 pm 
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Location: Durham NC
I am trying to "upgrade" my old aluminum mast to a comptip. I was able to purchase an old mast from someone that was severely dented on the bottom but had a comptip. I drilled out all the old rivets and then gave it a tug with my car and it popped right off. Just looking for info on getting it installed on my aluminum mast.

There's lots of gunk/glue/epoxy on it. I assume I can use a heat gun to remove the gunk? Should I sand it as well? Anything else I need to check? The plug on the bottom of the comptip looks like it's in their really well and sealed well so I don't think I need to worry too much about that.

Now as far as installing the comptip on my aluminum mast. I haven't cut my mast yet, but I have drilled out the rivets holding the tang on. What do I need to buy to install the comptip? Is there a comptip installation kit, with plug, glue and rivets I can buy? I haven't found anything on Murray's. Any advice on installing it is appreciated it. I've read over the PDF from Hobie on retro-fitting a comptip but I just want to be sure I have all the parts to get it done right.

We're finally starting to warm up here in NC and hope to get the boat in the water a few times before the wife pops out the baby.

Thanks,
Jim

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PostPosted: Mon Feb 24, 2014 1:06 pm 
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First off, keep in mind that the comptip is really only a safety "upgrade". It's purpose is to prevent injury or death from electrocution if the mast should contact a high tension wire. The other reason to install a comptip is if you want to do one-design racing, you are required to have one to race in North America. There is, however, no substantial performance impact when sailing with the comptip.

Personally, if I were not a racer, I would not cut a perfectly good mast. But, it's entirely your choice.

To install the comptip, you will need 3/16" diameter stainless steel pop rivets as well as the aluminum rivet "caps" which help seal the rivets. You also need a rivet gun which is capable of pulling the rivets. You will need a foam mast plug and the aluminum plate which gets installed over the plug. There is also a foaming kit used to fill the void between the internal mast plug and the bottom of the comptip (basically just that Great Stuff expanding foam insulation). Finally, you will need thickened epoxy resin which is coated over the comptip ferrule before inserting the tip. The epoxy is what gives the comptip a snug fit inside the mast.

For removing glue from the old comptip, I would use a belt or disc sander (carefully!). Remove all the old adhesive until you are back down to the original comptip material. I wouldn't use any heat as this will just create a sticky mess and could damage the comptip.

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PostPosted: Mon Feb 24, 2014 1:56 pm 
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Location: Durham NC
Thanks for the reply.

Just a quick question, do I need the mast plug and aluminum plate AND the expanding foam? From what I've read, 5200 on the plug and bondo or epoxy on the comptip. Any recommendations on epoxy?

I am really only doing this to be class legal as I'd like to get more involved with the local events. I actually have a pretty beefy rivet gun as I replaced my old track with a new one last year.

Thanks,
Jim

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PostPosted: Mon Feb 24, 2014 5:19 pm 
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I would use the plugs and expanding foam. This is the system that Hobie has evolved to as their best system for sealing the mast. The expanding foam fills the void between the primary plug and the comptip. You can get expanding urethane foam from uscomposites.com or you can just use the hardware store stuff in a can. There is also a small plastic cap that covers the hole after you foam the mast. I would use epoxy on the comptip not bondo. Bondo has a tendency to kick off really quickly and you want some time to be able to get the tip installed properly and get the rivets set. Any of the high end epoxies like West, System 3, MAS, uscomposites, or others will work. Thicken it up a little and have at it.

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PostPosted: Fri Feb 28, 2014 10:51 am 
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Yes you would need the spray foam. The purpose of the foam insert is to allow for the spray foam to fill only the top 4 inches or so. So it doesn't just run all down the mast. You could make you own out of anything really. The small plate is used to stuff the foam down and then insert the comp tip. Once installed then spray foam will create the seal from the comp tip down. The comp tip and up has its own foam built in to seal the tip. If the spray foam is not done than it will fill the mast and good luck getting the boat righted. We just used an entire tube of marine JB weld to epoxy the tip on. It really just fills the gaps and voids. The rivits and gravity hold it on.

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PostPosted: Sun Mar 02, 2014 3:54 pm 
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I was able to cut my mast today and install the plug and the plate with 5200. When I did a dry fit with the comptip only a couple of the holes lined up. So I guess I need to fill in the old holes. I have some polyster resin lying around that I've used for fiberglass repairs on my pontoons. It comes with some polyster strands that I usually mix in. Should I just use that to fill in the old holes and then drill new ones? Maybe use a syringe to squirt it into the holes? Or should I use something else? I assume the comptip is fiberglass?

Thanks,
Jim

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PostPosted: Tue Mar 04, 2014 9:56 am 
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Yes the tip is fiberglass, honestly if it was me I would stick it in drill the new holes and rivit it. I wouldn't worry about the old holes not linning up. The rivets just keep it from popping out. They don't hold and weight when sailing. The only time I would fill them is if there is absolutly nothing for the new rivits to bite onto. Like if they were wobbled out or broke to much material out of the mast. Just my opinion. Good luck!

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PostPosted: Tue Mar 04, 2014 10:11 am 
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How much difference is there between the old holes and the new holes? If you're in a situation where the new holes will partially overlap the old holes, then you're not going to get a good pull on your rivets and this is critical since the rivets actually do more than just keep the comptip from popping out. They are what holds the mast tang to the mast and are therefore what is ultimately holding your mast in the air.

I would not just fill the old holes with resin, that isn't going to provide any structural support for the rivets.

If the new holes cleanly miss the old holes, then I would just drill new holes and install the rivets. If the new holes overlap the old holes or are right next to the old holes, then I would say you really want to grind out some material and laminate fiberglass (cloth) over the old holes to patch them properly and then re-drill. I wouldn't use any polyester resin on a comptip. They are made using epoxy resin, so you should use epoxy. It will provide a much better bond.

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