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Old 13-10-2016, 13:32   #1
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Mast Bent While On The Hard

I had my aluminum mast in my yard while doing work on the boat and re-doing all the rigging and painting the mast. The mast was laying horizontal with the bow to stern direction facing up to minimize bending (this is strongest direction of the mast. I had the mast fairly well supported for a year like this. The mast did get rotated at times while working on it. the mast has a oval sectional dimension of about 6 inches by 9 inches. After a year on the hard the mast developed a bend in the port to starboard direction. I am fairly sure this will tune out when stepped as it does not take much force to correct the bend.

Just curious what would have caused the bend (maybe heating due to sun, I am located in tropics). Has anyone ever seen this happen? Bend is about 2 inches in the mid section of a 40 foot mast (bend causes mast to bow). Also, do mast ever reach end of life (would this be evident by cracks in the aluminum)?
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Old 13-10-2016, 14:07   #2
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Re: Mast Bent While On The Hard

Put the mast in the ground and see if the bend continue, 2 inches is to much in my eyes, probably you can live with it after re step and tune the rigging, we trash bend masts in the shop... they never get a proper tune after all.
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Old 13-10-2016, 15:26   #3
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Re: Mast Bent While On The Hard

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Put the mast in the ground and see if the bend continue, 2 inches is to much in my eyes, probably you can live with it after re step and tune the rigging, we trash bend masts in the shop... they never get a proper tune after all.
I am curious why/how the mast bent. It has been well supported and under no pressure.
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Old 13-10-2016, 16:17   #4
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Re: Mast Bent While On The Hard

I can't speak to the bend, but masts usually only meet their demise due to use on boats that are heavily raced, & that were marginally strong enough to begin with.
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Old 13-10-2016, 16:30   #5
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Re: Mast Bent While On The Hard

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I am curious why/how the mast bent. It has been well supported and under no pressure.
I have no idea, a year with a deflection in the middle can bent a mast..you mention painting the mast supported by the top head tip and base section right? do you supported the mast as well by the spreaders section? middle. or he spend a year hanging from head to base?
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Old 13-10-2016, 16:30   #6
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Re: Mast Bent While On The Hard

I doubt it's a permanent bend. You'd probably have to bend the mast 20-30 degrees for aluminum to take a permanent bend.
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Old 13-10-2016, 16:36   #7
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Re: Mast Bent While On The Hard

If the mast stay for a year supported by the 2 ends without support at the middle, is toasted, believe it or not....
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Old 13-10-2016, 17:11   #8
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Re: Mast Bent While On The Hard

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If the mast stay for a year supported by the 2 ends without support at the middle, is toasted, believe it or not....
Neil, I respect your experience and expertise, but I find this hard to understand. Aluminium doesn't experience cold flow like polymers, so what happens over time to ruin a mast supported only by its ends? I know from my own experience that short term exposure to those conditions does not permanently distort my masts... so I'm puzzled!

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Old 14-10-2016, 06:34   #9
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Re: Mast Bent While On The Hard

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Neil, I respect your experience and expertise, but I find this hard to understand. Aluminium doesn't experience cold flow like polymers, so what happens over time to ruin a mast supported only by its ends? I know from my own experience that short term exposure to those conditions does not permanently distort my masts... so I'm puzzled!

Jim
Hey Jim, I have no idea why, now what we have in our shop is several racks to store masts for long term storage, and they are spaced by 3 ft along the way, now even when we work in a large mast we try to hang the spar evenly by blocks and purchases when we leave it suspended in the air for a while, for a paint job or just repairs, leave the mast for a short time suspended by the 2 ends maybe have nil consequences now for a full year I'm not sure, even furlers can bent the foil sections if they are not properly stored.
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Old 14-10-2016, 11:32   #10
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Re: Mast Bent While On The Hard

Thanks for all the replies. I will be stepping the mast within the next few weeks and I will let you know if the bend tunes out. The mast was only supported by the ends for about a week while it was being painted. The mast was supported in the strong direction and the bend is in the weak direction (port to starboard). The mast has no bend in the strong direction (bow to stern). During the year, I was doing various jobs on the mast and it would be rotated in different directions (mast always lying horizontal). I always tried to support it every 10 feet or so along its length. The mast is a very stiff section, as it is deck stepped and a Rolly Tasker from 1978. The mast has two internal stiffener ribs that run the length from top to bottom the are located in the bow facing section of the mast. If I support the mast only at the two ends, and put about a 30 lb force in the middle of the mast in the weak direction to try to remove the bend, the mast will now be perfectly straight in all directions. When force is removed, the bend returns. I could try to put more force on the mast to try to yield the bend out, but would rather just tune it out with less force. So I am thinking when I tune the rig, by using the shrouds and the fwd and aft lower stays, I should be able to tune out the bend- I will post my results.
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Old 14-10-2016, 12:16   #11
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Re: Mast Bent While On The Hard

Let us know, but unless a couple of 200 pounders used it for a trampoline when you weren't there it either existed before or it should tune out easily.
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Old 14-10-2016, 13:30   #12
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Re: Mast Bent While On The Hard

Two inches in no big deal. The mast will flex more than that while it is being moved around. Rotate it bend up and you will see. Don't worry, no problem tuning it out.
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Old 14-10-2016, 16:32   #13
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Re: Mast Bent While On The Hard

if you rub your hands over the bent area do you feel any bulging or wow of the side wall? if so its probably shot.
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Old 14-10-2016, 17:20   #14
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Re: Mast Bent While On The Hard

Considering pre-bend isn't set much less than this, and is along the more rigid plane, I doubt it would be a problem.

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Old 14-10-2016, 17:32   #15
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Re: Mast Bent While On The Hard

One lower is going to be out of tune probably because that side need to compensate those 2 inches, in a single spreader mast maybe no problem , in a double or triple set of spreaders you can never reach a proper mast tune ...
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