I've got a broken mast that I'm going to (try) to fix.

My thought is to make a hollow carbon sleeve that would slip fit into the orginal section as a way to align the tubes and give me something to work off of when I taper back into the original section.

My question is: How best to create sleeve that would perfectly match the inside of the section?

Any creative ideas out there?

Bill

Is there any taper in the section you are going to work on? How far from the ends is the broken area (can you reach trough the tube)?

Rolf
The section is straight, not taper. The break is roughly in the middle of a 34' mast.

Are you thinking about pulling something out that would act like a mandrel? Balloon? Foam?

Just thinking as I type here Bill. What about priming the inside of each half with epoxy and matt then, while wet, inserting a wetted out matt of carbon wrapped around some kind of bladder/tube that you can inflate while it cures?

If you had to introduce a tube or two through the mast wall you'd be able to repair these holes afterward. You might be able to get some kind of polythene sleeve of the right diameter from a packaging supplier? It would only have to be approximately the right diameter, over not under.

Of course I may be way off base but that's the sort of aproach I'd take to get an initial repair and then I'd finish off on the outside.

I was thinking of using a compressor and inflating a piece of plastic or a cut and prepared inner tube from a wheelbarrow etc. inside the mast. This would squeze your laminate towards the wall of your mast, creating a very good sleeve. A layer of plastic and some precautions would need to be taken so you could get your sleeve out afterwards..
The problem is stopping the bag/tube you inflate from expanding and eventually bursting at the ends from the pressure. If it was relatively close to the ends, you could have worked from the other side. If you think about it and see what you can do, perhaps it's a strategy that will work. Got the idea from Phill and one of the methods he use to build tubes.

That gives me an idea....I'm wondering if I could set my vaccuum pump to blow....

How much pressure do you need? A typical wet/dry vac can be reversed by moving the hose from the intake to the outflow port.

BTW...since this procedure is called angioplasty for heart patients, would this then be a "mastioplasty" or an "angiomasty"? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

wet dry vac wouldnt work, you need something that would maintaine some sort of constant pressure, and cycle on and off like a vaccuum pump or something with a pressure valve.

Or I could make a bladder with a tire valve on it and pump it up and hope it doesnt leak. If I had to baby sit it and hand pump it with a bike pump periodically, that might work.

Any inner tube experts out there?

Bill

How about an air compressor with a regulator? <img src="http://www.catsailor.com/forums/images/graemlins/confused.gif" alt="" />

I'm wondering, though, how you get the sleeve back out of the mast after you've formed it since there is no release angle? That would be a bit tricky unless the sleeve were flexible because even with most release agents I've used, the resin still 'sticks' a good bit...If the sleeve were flexible then it wouldn't serve the purpose.

Brainstorming on the wild side, you could pour a plaster-of-paris (or rock hard putty - better binders) mold inside the mast (grease with Vaseline) and then make a two part mold for the sleeve from that. The plaster releases from vaseline very easily. I'm not sure how you would seal off the area of the mast you didn't want the plaster to go or if you could stand the other area up. Mold in some sort of handle with which to pull out the plaster plug. You might be able to accomplish a similar thing with foam, but I don't have much experience with how to get it to release.

There is a liquid rubber/eurythane material available that I researched when I was considering making my own CatRax wings for my Prindle 18.2. I was considering using it as a crossbar insert to support and cushion the wing inserts. It's a liquid that when it cures, solidifies at varying hardness levels, from soft rubber up to as hard as a bowling ball. If you first insert a shaped plug into the mast and coat the inside of the mast with mold-release, you could pour the liquid into the upright mast and let it cure and harden. Then pull out the hardened insert, pull up the plug and you have a perfect form-fitted mast insert from which to slide on the other half of broken mast. I don't think there's a way to actually get the insert out once you repair the mast, so if you epoxied it place, you would just have additional weight on your mast at that point of the break. But it would also provide an additional measure of structural rigidity at the point of the break.

What kind of mast? Carbon? Aluminum? How would you repair it? Weld it? Glue it? Welding aluminum is not the easiest thing. And to be honest, I believe the mast would be considerably structurally weaker than before that it wouldn't last long and fail again. This may be a futile endevour. Masts and rigging undergo signifigant stresses under sail.

I don't have the URL to the company that makes the stuff with me right now. If you PM or e-mail me, I can find it when I go home tonight.

Hey Bill
Are you fixing Tyler's mast. I have another one if your up for the challenge. I have a friend that worked for Hall. I will ask him what they did to fix carbon masts.
Barry

One method for getting a sleeve out of a mast with the "pressure" method could be to apply a relatively thick layer (0.5-1mm) of beewax or similar. Apply the wax first, then do the lamination. When the matrix has hardened, the wax can be melted and the sleeve pulled out. Again, something Phill came up with.

Hey, that is a flippin cool idea <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

How about duct tape? Keep it simple.

I have an endless supply of "bladders", used hospital pressure bags, (the occasional blood stains are free)
They are about the same size as a mast ssection.

Dave
Do they have a valve on them that I could pump up? Can you post a picture?

Bill

OR... you could cut it in half and sell each half as a F12 mast!

From what I can tell there is not a "valve" but you could make an adapter to inflate it and then seal it to keep the shape.

Would a tyre tube work as it has a valve attached

Great cheap idea. The tube will conform to the shape. You can fold it to the desired length and throw a loose wrap of "duct tape" on it.

If you can't fix it, caulk it. If you can't caulk it, duck it, if you can't duck it, ,,,,,,,,,,,