mast bend - SailNet Community
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post #1 of 8 Old 08-24-2017 Thread Starter
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mast bend

Hi all, just noticed something about my 1986 Pearson 303.The mast about 3 foot from
the top has a slight bend in it. The bend is toward the stern all standing riggings appear
to be fine. Is this a problem or was the mast built this way. thanks
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post #2 of 8 Old 08-24-2017
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Re: mast bend

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Originally Posted by thumper53 View Post
Hi all, just noticed something about my 1986 Pearson 303.The mast about 3 foot from the top has a slight bend in it. The bend is toward the stern all standing riggings appear to be fine. Is this a problem or was the mast built this way. thanks
That is a problem. The 303 was designed and built with single spreader rig, inline spreaders and a stiff spar that should not not have a bend in it at the area that you describe. It is possible to have the upper and lower shrouds out of tune which would create a slight curvature from side to side, but that would be distributed over the length of the mast.

With a keel stepped mast (and no baby stay) it is also possible to have some fore and aft curvature, but again, that would be gentle and pretty much spread evenly over the length of the mast.

Localized as you describe, it sounds like your spar has been damaged at some point.

Jeff


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post #3 of 8 Old 08-24-2017
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Re: mast bend

Ease the backstay and observe whether the mast straightens.
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post #4 of 8 Old 08-25-2017 Thread Starter
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Re: mast bend

Thanks, going down to the boat this morning to get some pictures and will try easing the backstay.
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Re: mast bend

Randomly easing standing rigging is as likely to create new problems as it is to improve the situation. Because the mast is keel stepped, you need to sight up the track and try to see what is going on. If the mast gently curves aft, then you might actually need to tighten the forestay.

But before you do anything you need to try to figure out what is going on by methodically checking the mast step, partners, shroud and stay attachment points, and whether there are cotter pins in all of turnbuckles.

The key is to get your eye next to the mast track and carefully sight where the curvature is actually occurring. If the curve is a smooth and even curve then it comes down to moving the masthead forward a little which can be done with either tightening the forestay or easing the backstay a little depending on the adequacy of your headstay tension. But it you have an S curve, which is more likely If you see a tight curve near the top of the mast, you need to move the mast head a lot more, and that will require loosening the backstay and tightening the forestay while paying attention to the rest of the the rig tune.

Lastly, if the bend is really in the last 8-10 feet of the mast, then the spar needs to be inspected because that sounds like the spar itself has been damaged since there is nothing in your rig geometry that can cause that benignly.

Jeff
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Last edited by Jeff_H; 08-25-2017 at 09:05 AM.
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post #6 of 8 Old 08-25-2017
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Re: mast bend

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Originally Posted by thumper53 View Post
Thanks, going down to the boat this morning to get some pictures and will try easing the backstay.
Probably too late if you went down this morning! But one thing you could do, is pull the main halyard tight with shackle end tight to mast at gooseneck. Then sight up from side. You should be able to see how much bend you have and where maximum offset occurs.

Then also check mast rake. Attach a heavy weight to halyard shackle and see how far back from mast halyard it is at boom level (need calm day and level boat!)

Some mast bend is desirable. It helps stiffen the mast. With single lowers and no baby stay, you can't really control where this happens.

Because of keel stepped mast, you can bend mast using backstay, then adjust forestay accordingly. Mast rake is controlled by just where foot of mast is in step as well as how it is wedged at deck level. You may be seeing a combination of some mast bend and mast rake. But good to check it out.
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Last edited by FreeAgent; 08-25-2017 at 03:32 PM.
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Re: mast bend

Thank you everyone! Just got back from the boat, and I was looking at it all wrong.
I was standing to the side of the mast looking up, the last 5 foot of the mast is tapered to the back. It was a optical illusion.
The indented ridge follows the taper, the back of the mast is straight.
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Re: mast bend

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Originally Posted by thumper53 View Post
Thank you everyone! Just got back from the boat, and I was looking at it all wrong.
I was standing to the side of the mast looking up, the last 5 foot of the mast is tapered to the back. It was a optical illusion.
The indented ridge follows the taper, the back of the mast is straight.
Unusual to have taper on masthead rig, but I have seen it before. Maybe something like this one:

mast bend-tapered-mast.jpg

Anyway, that should ease your concerns
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