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Mast rotation?
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=11353		 Page 1 of 1
Author:  Burley Burlando [ Wed Dec 10, 2008 7:11 pm ]
Post subject:  Mast rotation?
My mast has a slight bend and has a hard time staying to the one side. My crew has to use their foot to keep it over in light wind. I don't have the balls to try and straiten it. I fear breaking the mast. It would cost over $2000 to get a new mast up here. Would a Aussie Jib Halyard help?
Author:  mmiller [ Thu Dec 11, 2008 10:43 am ]
Post subject: 
Counter rotation is caused by many things, but a bent mast is certainly one that may be correctable. I would try if the bend is slight and not a kink. I have done this.

Place on a couple of padded milk crates... next to something to hold onto. Spread the crates wide to either side of the bend. Roll the mast over so the bend is up. Have someone hold it there as you step onto the mast (balance beam style / holding the fence or object you are next to for balance). You want to load carefully and then if the initial load is not enough... take a bounce and then bounce a bit harder until the mast bends a bit in the right direction. Keep checking. I bounced pretty hard and at about 180, at the time ;o), it took significant effort to bend it.

The aussie halyard can help. You can easily test by reducing the existing halyard tension and seeing if that seems to help.
Author:  MUST5429 [ Thu Dec 11, 2008 11:20 am ]
Post subject: 
I have a problem with the "bounce" technique of mast straightening.
You run the risk of overdoing it in the other direction, or "kinking" the mast.

I have used two other techniques that I like a lot better.

The first is to place the mast on a couple of strong stable platforms, possibly saw horses, line them up with the base of the mast and a point near the mast hound, NOT on the comp tip. and then place a ratcheting strap at the point of maximum bend, with a short length maybe 18 inches of 2X4 to spread the load so that you are not "point loading" the mast.

Anchor the other end of the racheting strap to the ground, using a sand screw or some other method of getting a firm, strong and stable connection.

Then start racheting downwards in measured increments occasionally relaxing the strap and sighting down the luff track to check your progress, going a little further down each time until you have gotten the mast straight.

The second method I have used with a great deal of success is to place the mast under a couple of anchor points, (I Used the trailer hitches of a couple of trucks parked side by side and lined up with the base of the mast and a point near the mast hound, NOT on the comp tip.)

Then place a floor jack or a bottle jack at the point where the bend inthe mast is greatest, once again use a short length of 2X4 to spread the load and avoid "point loading", and begin jacking up on the bend, stopping occasionally and relieving the pressure and checking for straightness by sighting down the luff track. Proceed carefully, in measured increments so that you get it straight without overdoing it.

I have had excellent results using these methods.

Stephen
Author:  mmiller [ Thu Dec 11, 2008 12:27 pm ]
Post subject: 
Certainly sounds way more "controlled" than my idea!
Author:  sunjammers [ Thu Dec 11, 2008 1:30 pm ]
Post subject: 
We have 2 palm trees at the store we use. We just put the mast in there and apply pressure to straighten it out. I've not damaged one yet but could see how it could happen. its takes a lot of pressure to get them to bend.
Author:  Burley Burlando [ Thu Dec 11, 2008 6:46 pm ]
Post subject: 
I like the two hitches and a floor jack idea. Does a mast want to bend easer once it has been bent? Mine has a two inch curve in it at the botom ten feet.
Author:  MUST5429 [ Thu Dec 11, 2008 7:22 pm ]
Post subject: 
Easier is a relative term, I've never bent one on purpose to see if it was easier to straighten it.

I'll say this, they aren't all that easy to straighten.

Stephen
Author:  MBounds [ Fri Dec 12, 2008 10:36 am ]
Post subject: 
Burley Burlando wrote:
Does a mast want to bend easer once it has been bent?


It actually gets harder to bend because of stress hardening.
Author:  ajsemtb [ Mon Apr 20, 2009 7:39 am ]
Post subject:  Re: Mast rotation?
After reading these posts, I successfully straightened (within a 1/4") a bend that was at least 2" if not a little more by using the floor jack suggestion. It take AN ENORMOUS AMOUNT OF BEND to bend a mast! It's hard to think how these get bent unless they get dropped, because of how much force it took to straighten mine. The saw horse idea didn't work, I kept pulling the ground screw out (which either wasn't big enough, or too sandy soil...) and I broke a saw horse trying to manually bend the mast. The mast was bent, but wasn't straightening with the amount of force I and a friend could inflict on it. However, it was too much for the saw horse and the wood broke on it... :shock:

However, 2 vehicles, a 2.5 ton hydraulic floor jack and 4 attempts and blocking (once the jack reached its top each time) and I have a straightened mast. I used a piece of 1x4 as my initial block, and cushioned the mast under the trailer hitch pins, next time I added a 2x6 to the 1x4, the next time I added a 2x under one of the hitch pins (the other side was bending into the ground because the trucks weren't exactly the same height so I only added blocking to the high side) then finally, the last time, added another 2x to the same hitch pin, and that was enough blocking at max height with the jack to straighten the mast. It looked like an upside down U almost. But when it lowered down, It was straight, so just know that it looks scary, but it works!

I should mention, I have another mast (not a comp tip) so if I destroyed this one, I had a back up.
Author:  Little Wing [ Mon Apr 20, 2009 10:25 am ]
Post subject:  Re: Mast rotation?
I would say that you got somewhat lucky. from what I have seen over the years, the best way to avoid kinking the mast as you try to bend it back the other direction is to fill the mast with sand, block it on the ground and apply weight to the opposite side of the bend, but sounds like you got lucky, yippeeee.
Author:  ajsemtb [ Mon Apr 20, 2009 11:10 am ]
Post subject:  Re: Mast rotation?
I've never heard that way before. Mine had a piece of 16-18"? wood under it to avoid focused pressure. The length distributed the load over and are 16-18" as opposed to just the point of lift. I talked to my local hobie shop and they said the just wrap the mast in bubble wrap, put it against a telephone pole, put a guy on either side and start pushing until its straight... The skinny is this, its very hard to bend a tube of any kind. Your mast is essentially an aluminum tube. It can collapse because it is hollow, however if you are careful, work slowly, and gradually, you will fix the bend.
Author:  Burley Burlando [ Mon Apr 20, 2009 4:33 pm ]
Post subject:  Re: Mast rotation?
I just can't get the balls to try. My sailing days will be done if I kink my mast!
Author:  yoh [ Wed Apr 22, 2009 9:48 pm ]
Post subject:  Re: Mast rotation?
Try it! I have done one a few years ago that got bend. I used a variation of the describe “hydraulic car jack” method. I also considered the Palms tree method – even though in my case it would have been Live Oak (assuming that the species of tree would not matter that much).
In my situation I ended up resting the mast on sandbags while I centered the bend under the garage doorframe. I also used a sand bag to spread the load under the jack (in my opinion this is better then the “2x4 approach”). I braced the jack under the frame and pumped... I remember that I had to significantly over bend the mast. Clamping a measuring stick next to the mast helped to gage the progress. There is lots of elasticity in those masts. Essentially you pump the jack to a certain point on the measuring stick – release – check for progress – pump again until you are there…
I would not sail with a bed mast... but to be honest I got a straight used mast before I tried to straingent the bend mast. I am still saying try straightening that bend!!! It is less of a risk then you talking your self into…


Patrick
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