Mast Bent While On The Hard

[F10]

Originally Posted by bsurvey

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.

There are no bulges any where. The bend is along the entire length, like a bow (as in bow and arrow). I can get rid of the bow by pushing (about 30 lbs force) in the middle of the mast. Also the bend is on the weak axis of the mast (port to starboard direction).

[F10]

Originally Posted by neilpride

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 ...

Mine is just single spreader. What I am wondering is what caused the bend to begin with, seems the mast just creeped due to maybe heat effects of the sun. I am hoping once I tune the rig, over time the mast will creep back to its straight position again and would stay that way even if it were to be taken off the boat. Seeing it will take only 30 lbs horizontal force to correct the bend, should not be too much difference in the tuning tension on the wires as the lowers will be set between 800 and 1000 lbs.

[n13L5]

Sounds to me like Masts need truss rods, like guitar necks...

[zeehag]

my yacht builder friend used to turn the mast over and support it in a different manner to straighten em out.
OR you can buy a new one for about 15000 usd, new.
your choice.
hanks masts that he turned over did not subsequently have any issues.

[neilpride]

Originally Posted by F10

Mine is just single spreader. What I am wondering is what caused the bend to begin with, seems the mast just creeped due to maybe heat effects of the sun. I am hoping once I tune the rig, over time the mast will creep back to its straight position again and would stay that way even if it were to be taken off the boat. Seeing it will take only 30 lbs horizontal force to correct the bend, should not be too much difference in the tuning tension on the wires as the lowers will be set between 800 and 1000 lbs.

Can you post a picture ? a bend mast is a bend mast, i mean there is no way back to OEM extrusion shape, 6061 alu grades are heat friendly but there is no way to straight the mast again to the original shape , saying that if you are sure there is no hard spots or kink spots it could be ok if the 50% of the bend lenght is at the spreaders lowers point, just check by the mast mainsail track when you finish the rigging tune if is straight,, i told you a example, some time ago a couple come to our dock by a rigging inspection , 2 spreader tall mast, all fine excpet for a spagueti form in the spar, several attempts in the d1 and d2, uppers lowers and no way to put the mast in column, after all we loose all and found the mast bent between the 1 set and and 2.

Yours could be fine if the bend spot is at the Lowers tangs, why is bend and why happen is a mystery for me, we have a sparcraft and selden bulletin to how store masts in the racks, we know by experience that masts need to be keep as straight as posible when they are stored or working on it, is not a big deal tow a long mast in the dolly for a while with a hig bend compared to store a mast with a huge bend for a long time.
Could be a manufacture defect and you notice it now?
Could be heat and long term storage?
Could be out of tune for long time?
Could be the yard throw someting or leave a heavy object in the mast?
No idea.

[HappyMdRSailor]

Just out of curiosity, where are your spreaders in relation to the maximum deflection???

Just an FYI

Running a quick calc on bending moment for your Rolly stick T11A, I get nearly 1/2 the yield strength stress in the middle if only supported by the ends lying sideways... This is a bare stick without your stiffeners/holes/bolted shiznit... It wouldn't take much extra to bend it! Like bird/paintbrush/mosquito...

I kid...

WAG is you're going to be fine tuning... but Neil is the spar guru here on CF...
I'd pay close attention to what he has to say...

[neilpride]

Thank you happy, and just to end my little help here maybe, F10 , could be the bend a visual cheat?? I mean are you try to put the mast in a perfect flat surface and see if the mast retain the shape?

[F10]

If all goes well, should be stepping the mast in a week. Yesterday I took a piece of weed wacker plastic line (that I can tension very tight) and stretched it from the mast base to the mast tip. The bend is constant along the entire length of the mast. At the mid point of the mast the deflection of the mast from the taught line is 1 inch. This 1 inch is located approximately at the spreaders which are close to the mid point of the mast (this is single spreader rig). This bend might have been there when I started the work a year ago, maybe I missed it. Applying about 30 lbs of force at the bend, and with the mast supported only at the ends, the mast will be straight, but will spring back when force is removed. Note the bend is in the weak direction, port to starboard. The bow to stern direction the mast is perfectly straight.

So if a mast is stored incorrectly, does it then creep and can get bent? I understand aluminum has no fatigue limit, is this a factor? Note I did a complete inspection of the mast and I see no bulges, dents or bends, no cracking, and very minor corrosion where some fittings were attached to the mast. All corrosion was sanded down and primed zinc chromate and then painted. The mast has been at my house and I helped take down and transport the mast- never left my sight.

[neilpride]

Originally Posted by F10

If all goes well, should be stepping the mast in a week. Yesterday I took a piece of weed wacker plastic line (that I can tension very tight) and stretched it from the mast base to the mast tip. The bend is constant along the entire length of the mast. At the mid point of the mast the deflection of the mast from the taught line is 1 inch. This 1 inch is located approximately at the spreaders which are close to the mid point of the mast (this is single spreader rig). This bend might have been there when I started the work a year ago, maybe I missed it. Applying about 30 lbs of force at the bend, and with the mast supported only at the ends, the mast will be straight, but will spring back when force is removed. Note the bend is in the weak direction, port to starboard. The bow to stern direction the mast is perfectly straight.

So if a mast is stored incorrectly, does it then creep and can get bent? I understand aluminum has no fatigue limit, is this a factor? Note I did a complete inspection of the mast and I see no bulges, dents or bends, no cracking, and very minor corrosion where some fittings were attached to the mast. All corrosion was sanded down and primed zinc chromate and then painted. The mast has been at my house and I helped take down and transport the mast- never left my sight.

Do you try to see if the bend is still there with the mast resting in the floor, because with the mast supported just by the 2 ends a bend is a normal thing, the mast flex ... quite normal if you just support the 2 ends...

[HappyMdRSailor]

Originally Posted by F10

If all goes well, should be stepping the mast in a week. Yesterday I took a piece of weed wacker plastic line (that I can tension very tight) and stretched it from the mast base to the mast tip. The bend is constant along the entire length of the mast. At the mid point of the mast the deflection of the mast from the taught line is 1 inch. This 1 inch is located approximately at the spreaders which are close to the mid point of the mast (this is single spreader rig). This bend might have been there when I started the work a year ago, maybe I missed it. Applying about 30 lbs of force at the bend, and with the mast supported only at the ends, the mast will be straight, but will spring back when force is removed. Note the bend is in the weak direction, port to starboard. The bow to stern direction the mast is perfectly straight.

So if a mast is stored incorrectly, does it then creep and can get bent? I understand aluminum has no fatigue limit, is this a factor? Note I did a complete inspection of the mast and I see no bulges, dents or bends, no cracking, and very minor corrosion where some fittings were attached to the mast. All corrosion was sanded down and primed zinc chromate and then painted. The mast has been at my house and I helped take down and transport the mast- never left my sight.

This all sounds like good news to me! Well... better news anyway... UNBENT is good news!

1" is far better than 2", AND max deflection is at the spreaders... I'm betting that you won't even have to tune it out... Meaning I'm guessing it will disappear under even shroud tension... I am HOWEVER... Not a professional RIGGER

According to Neil previously, creep can happen to improperly supported sticks... and YES, Aluminum DOES have a fatigue limit, as does just about everything...

The attached says 14ksi, albeit 50 million cycles of +/- 14ksi, but that's what it is... My prior quick calculation was that lying on it's side supported at the ends, the center saw 14.27ksi, but no way did it cycle +/- that... let alone 50M times...

Party on...

[neilpride]

Yeah , so if you loose the side rigging like uppers and lowers and leave the forestay and backstay tensioned the mast bend , and if they are really tight the bend is insane , I guess you know what I'm trying to say, check with the mast all along well rested in a flat surface and maybe you found a surprise...

[HappyMdRSailor]

Another option is to store it for a year bow side up and see if you luck out in 10/17...

(sorry... that's not even funny as I type it)


maybe a little...

[F10]

Originally Posted by neilpride

Do you try to see if the bend is still there with the mast resting in the floor, because with the mast supported just by the 2 ends a bend is a normal thing, the mast flex ... quite normal if you just support the 2 ends...

If I support the mast at two ends with the mast oriented in the strong direction (like a "I" beam) the mast will be straight in the vertical direction (no bow in the vertical direction), however it will be bowed in the horizontal direction. If I support the mast at two ends in the "weak" direction, even orienting so the "bow" is up the bow will still exist. If I now put about 30 lbs force in the middle of the mast (still supported at the ends in the "weak" direction with the bow up), the bow will disappear, but reappear when the 30 lb force is removed.

[neilpride]

Originally Posted by F10

If I support the mast at two ends with the mast oriented in the strong direction (like a "I" beam) the mast will be straight in the vertical direction, however it will be bowed in the horizontal direction. If I support the mast at two ends in the "weak" direction, even orienting so the "bow" is up the bow will still exist. If I now put about 30 lbs force in the middle of the mast (still supported at the ends in the "weak" direction with the bow up), the bow will disappear, but reappear when the 30 lb force is removed.

What I'm trying to say is that if you support the mast at the 2 ends make no diference if you want to see if is bend or not, if tomorrow I get a spar and support it by the 2 ends probably I'm going to see one side wobbling...
its 40 ft long, I doubt you can see anything straight 40 ft long supported by the 2 ends.. because you are facing the mast in the supports in the strong direction, the flexing need to go somewhere , usually at the weak sides..thats why I suggest put the spar at the floor free of loads and tension and see if is bend or not, to be sure...

[F10]

Originally Posted by neilpride

What I'm trying to say is that if you support the mast at the 2 ends make no diference if you want to see if is bend or not, if tomorrow I get a spar and support it by the 2 ends probably I'm going to see one side wobbling...
its 40 ft long, I doubt you can see anything straight 40 ft long supported by the 2 ends.. because you are facing the mast in the supports in the strong direction, the flexing need to go somewhere , usually at the weak sides..thats why I suggest put the spar at the floor free of loads and tension and see if is bend or not, to be sure...

To test for bending, I am taking a 40 foot long, thin weed wacker plastic line and tensioning it to 50 lbs. I can position this line along all sides to the mast to test for bending. In the strong direction the mast has no bend. In the weak direction it has the 1 inch bow bend in the middle. Makes no difference how the mast is rotated or how it is supported the 1 inch bend is always there. The bend is there no matter if the mast is supported at the two ends or supported equally every 10 feet, the bend is still present. The mast weighs about 200 lbs. I can pick up one end and rotate it (other end supported on the ground) and the bend is always present and in the same location.