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Old 08-04-2015, 07:27   #1
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Broken Mast

I understand that sleeving a mast is a standard practice. My mast was sleeved from the factory at the forty foot point. Which I might add did not snap there. Finding the same type mast to sleeve it has not proven to be fruitful. Here is my question. Can you tell me one good reason why I can't have a aluminum Ibeam made to fit inside the mast at the break and rivet or thread the beam to allow for screwing it back together? Is it posialbe that this area will be to strong? I don't tweak my mast with the back stay for performance. I am a live aboard cruiser. Thanks in advance for any experienced feedback. I think outside the box most the time it works, sometimes not so well. Putting stay loks on everything is killing me so a new mast is not a alternative.
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Old 08-04-2015, 07:38   #2
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Re: Broken mast

why not just go to a metal fabricator with a roller press?

given a template they can fabricate the correct size sleave out of aluminium plate.
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Old 08-04-2015, 09:27   #3
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Re: Broken mast

That's is probably one way of going about it. My question still is. Any reason a custom ibeam won't be even stronger?
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Old 08-04-2015, 10:20   #4
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Re: Broken mast

The mast flex at the sleeve joint , believe me , is not much , but under great loads flex, a I beam is not going to work , the 2 joints in compresión rest with each other at the joints faces but the rivets are doing most of the work , what a sleeve is doing is keep the 2 joints aligned with each other so they cant dislodge the joints ends take the loads and the rivets to, with a I beam you are making in fact hard spots ,,, if your mast is from a reputable spar maker you can order a sleeve,,, talking about wich one is stronger, the sleeve won because he can spread the loads even ....
cheers...
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Old 08-04-2015, 15:06   #5
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Re: Broken mast

I am in fact creating the same as a sleeve joint with the eye beam being the sleeve So I am still standing on my ibeam unless someone comes up with more help. I'm not being stubborn if you don't believe in yourself you will follow anyone.
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Old 08-04-2015, 15:17   #6
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Re: Broken mast

Hi S.G.,
'Not an engineer so I probably should not even open my mouth but I believe a mast is a monocoque structure where the tension, compression and shear all run in the "skin" which is of course the whole mast. A discontinuity that is not evenly and intimately joined at the skin will not transmit the load well. You'll end up with thousands of pounds of pressure at the small bolting points and failure of the I-beam there might occur. Then there's the issue of all the stuff that runs in the mast...
Good Luck,
Dennis
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Old 08-04-2015, 15:23   #7
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Re: Broken mast

Also keep in mind you want to minimize your weight aloft. A large i-beam will weigh much more than a sleeve.
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Old 08-04-2015, 15:34   #8
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Re: Broken mast

A structural I beam on or in your mast is not the best and may have negative values. If the manufacture of the mast is sill in business they may give you some technical support on what is the best solution. The engineering for mast has advanced a lot. Most likely most masts have a weak point, engineers are now capable of splicing extrusions at stronger levels. Shopping for a used one may be also be a better and safer bet.


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Old 08-04-2015, 19:28   #9
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Re: Broken mast

I just went through my own mast "repair" situation. There is a thread I started for it.

I'll save you the trouble of looking, you know what I learned? Every single person that posted the same things they are posting here, on your version of a mast repair thread, were all correct. What I tried... failed.

It's 2015. Sailors have been repairing masts for many decades now. If there was a better way to do it, we would all be doing it that way.

I ended up buying a used mast for $50, cutting it to fit, transferring the rigging to it and sailed it last Thursday.

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Old 09-04-2015, 07:54   #10
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Re: Broken mast

Quote:
Originally Posted by Fiveslide View Post
I just went through my own mast "repair" situation. There is a thread I started for it.

I'll save you the trouble of looking, you know what I learned? Every single person that posted the same things they are posting here, on your version of a mast repair thread, were all correct. What I tried... failed.

It's 2015. Sailors have been repairing masts for many decades now. If there was a better way to do it, we would all be doing it that way.

I ended up buying a used mast for $50, cutting it to fit, transferring the rigging to it and sailed it last Thursday.

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What did you try?
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Old 09-04-2015, 08:04   #11
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Re: Broken mast

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Originally Posted by Gypsea Soul View Post
What did you try?
I tried to straighten a bent mast and get a small dent out of it. I couldn't sleeve mine because it was bent right at the internal halyard entry. So I shopped for weeks until I found a replacement, a cheap one.

My point was that you will find these guys are right when they are telling you to sleeve it. They certainly predicted exactly what would happen to mine when I tried to straighten it.

And if your situation begins to look like mine, and replacement is the best option, do let us know what size mast you need. I'd be happy to help you shop the used market, there are incredible deals out there.

Good luck with it.

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Old 09-04-2015, 08:17   #12
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Re: Broken mast

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Originally Posted by Fiveslide View Post
I tried to straighten a bent mast and get a small dent out of it. I couldn't sleeve mine because it was bent right at the internal halyard entry. So I shopped for weeks until I found a replacement, a cheap one.

My point was that you will find these guys are right when they are telling you to sleeve it. They certainly predicted exactly what would happen to mine when I tried to straighten it.

And if your situation begins to look like mine, and replacement is the best option, do let us know what size mast you need. I'd be happy to help you shop the used market, there are incredible deals out there.

Good luck with it.

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One of the problems I have with just replacing it is. I like where all my winches are located in other aspects of the mass I have decided I am going to sleeve it I'm just going to sleeve it with a custom aluminum Ibeam I'm not reinventing the wheel just making it stronger. Finding a sleeve to fit in this forty year old mast is not bearing fruit.
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Old 09-04-2015, 08:25   #13
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Re: Broken mast

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Originally Posted by Gypsea Soul View Post
One of the problems I have with just replacing it is. I like where all my winches are located in other aspects of the mass I have decided I am going to sleeve it I'm just going to sleeve it with a custom aluminum Ibeam I'm not reinventing the wheel just making it stronger. Finding a sleeve to fit in this forty year old mast is not bearing fruit.
You're not going to find one. It would have to be made, just like your custom ibeam. It would probably be cheaper to get an aluminum plate rolled into a sleeve than a bunch of aluminum plates cut perfectly, and welded perfectly, to fit perfectly into your mast.

I have an engineering background, it's not in mechanical or structural or anything that really applies here, but I think the strongest repair would be a sleeve, rolled to fit your mast's curvature and riveted into place.

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Old 09-04-2015, 08:51   #14
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Re: Broken mast

Welding reduces the strength of aluminum by 50%. I beams only resist bending in two directions, mast requires 360 degrees. Make a tight fitting sleeve, or replace that are your only functional chooses.


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Old 09-04-2015, 08:53   #15
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Re: Broken mast

Quote:
Originally Posted by Gypsea Soul View Post
I understand that sleeving a mast is a standard practice. My mast was sleeved from the factory at the forty foot point. Which I might add did not snap there. Finding the same type mast to sleeve it has not proven to be fruitful. Here is my question. Can you tell me one good reason why I can't have a aluminum Ibeam made to fit inside the mast at the break and rivet or thread the beam to allow for screwing it back together? Is it posialbe that this area will be to strong? I don't tweak my mast with the back stay for performance. I am a live aboard cruiser. Thanks in advance for any experienced feedback. I think outside the box most the time it works, sometimes not so well. Putting stay loks on everything is killing me so a new mast is not a alternative.
You could but its not a very elegant engineering solution.

Your mast must carry a primary compression load. If your standing rigging is tensioned correctly then your mast will experience little in the way of bending loads. A thicker column will have better resistance to buckling than a slender column. Buckling is the primary failure mode.

If your mast is subject to bending then adding material as far apart is how we engineer bending strength.

In both cases your I beam solution is less effective than adding material around the mast like a sleeve or collar. As others have suggested.

You also have issues like halyard and cable routing to consider.

This is a basic engineering problem. There is no rocket science or propellor hats required.

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