Mast repair options

[valhalla360]

Originally Posted by jimbunyard

Don't think I'm the one who's missing the point, as a careful consideration of the relation between the web of an I-beam and its' upper and lower flanges as analogous to the relation between the faces of a rectangular tube. Or perhaps you missed the 3.5" x 1.5" holes on either side of the 'wide' dimension of the rectangular aluminum tube (mast) that would tend to disprove the point you seem to be trying to make.

Perhaps you also missed "If it were not for the need to have something to anchor the spreader base" from my post.

If the mast had no stays or spreaders, it would just be a flagpole; the stayed mast acts as a complete system to support sail loads, one can't eliminate one part and expect the system to be functional.

Would be interesting to find where your 75% number comes from...and if it refers to the mast by itself or in combination with its supporting structures.

An I-beam is only designed to resist bending in only one direction. The web resists shear force but that tends to be a small stress so it's usually OK to put holes in it (within limits). If you try to bend an I-beam side to side, it tends to be very weak.

In terms of the side to side bending of the mast (as opposed to fore & aft bending), this damage is equivalent to completely removing one of the flanges for a short distance at the highest stress location.

I suggest a structures course to understand why it's likely around 75%. If you don't understand, it would take a few hours to run thru how to calculate it. No I didn't run the calculations so I'm not guaranteeing it to the nearest percent but I guarantee it's well over 50% loss of strength in terms of side to side bending.

[chris95040]

Originally Posted by jimbunyard

Generously, the damaged area appears to be about 5" x 5", so say about 25 sq in. Assuming a 60 foot mast on a 47 foot boat, that's 720 inches times about 8 inches (the width of the side), so that's 25 square inches out of 5760. Or (I think) about .44 % of the 'whole side'.

Somewhere deep down you knew I didn’t mean along the whole height of the mast.

Originally Posted by jimbunyard

...virtually none of the structural integrity of the mast has been compromised.

To the OP... Please make sure a (sober) expert looks at that mast.

Remember, although aluminum masts are typically way stronger than necessary for the straight compression loads they are expected to see, their fitness for our purposes comes in part from their ability to withstand buckling failure. I’m no expert but it sure looks to me like that mast would buckle sooner with the majority of one side missing in the damaged area.

[Elie]

When the mas was raised, il was attached by a sling on each (roughly) end of the extrusion. It was heavy, since the main sail was still rollen into the mast. It did not bend nor showed any risk of breaking.
We have to keep in mind that the internal 'tube', solid internal part of the extrusion for the in-mast furler, increases seriouslly the overall strength of the extrusion, obviously. Anyway, in this area(lower spreaders) this is a 4.5x 1.5 in hole for the bar that goes trough the extrusion. So the 'breakage' is less terrible then it looks. And keep in mind that the break occured only on the flat area of the mast, and nothing occured to the front and rear of the(rounded) profile . I'm sure that plates on each side on the break would add to the actual strength of the mast at this place. In fact I'm thinking of doubling also the upper spreaders in the same fashion. Just in case!
By the way thank you all for your positive support of my problem. IT IS GREATLY APPRECIATED!.

[chris95040]

Originally Posted by Elie

When the mas was raised, il was attached by a sling on each (roughly) end of the extrusion. It was heavy, since the main sail was still rollen into the mast. It did not bend nor showed any risk of breaking.

But how was the mast oriented in the slings? I imagine fore/aft were top/bottom, and you may have had very different results if it were rotated 90 degrees.

Originally Posted by Elie

We have to keep in mind that the internal 'tube', solid internal part of the extrusion for the in-mast furler, increases seriouslly the overall strength of the extrusion, obviously.

Maybe, but being relatively small in cross section compared to the mast, it may not contribute much stiffness at all. It may be more like having a spaghetti noodle threaded through a drinking straw, not necessarily contributing much.

Originally Posted by Elie

Anyway, in this area(lower spreaders) this is a 4.5x 1.5 in hole for the bar that goes trough the extrusion. So the 'breakage' is less terrible then it looks.

Another way of looking at it is the damage is all the more significant since that area already had less margin.

Originally Posted by Elie

And keep in mind that the break occured only on the flat area of the mast, and nothing occured to the front and rear of the(rounded) profile . I'm sure that plates on each side on the break would add to the actual strength of the mast at this place. In fact I'm thinking of doubling also the upper spreaders in the same fashion. Just in case!
By the way thank you all for your positive support of my problem. IT IS GREATLY APPRECIATED!.

I think you are right that a good fix is not going to be very complicated. But I’m not sure I’ve heard you agree that a bonafide expert is going to design that repair, and that would be unwise. There’s likely more to mast design than you think there is, and failure of a mast that size could kill somebody.

[Elie]

Originally Posted by chris95040

But how was the mast oriented in the slings? I imagine fore/aft were top/bottom, and you may have had very different results if it were rotated 90 degrees.




Maybe, but being relatively small in cross section compared to the mast, it may not contribute much stiffness at all. It may be more like having a spaghetti noodle threaded through a drinking straw, not necessarily contributing much.



Another way of looking at it is the damage is all the more significant since that area already had less margin.




I think you are right that a good fix is not going to be very complicated. But I’m not sure I’ve heard you agree that a bonafide expert is going to design that repair, and that would be unwise. There’s likely more to mast design than you think there is, and failure of a mast that size could kill somebody.

The mast was pulled on its larger side parallele to the ground, the broken side under(in extension), with the weight of the sail.
The in-mast 'extrusion', is in fact part(not welded or attached later) of the whole extrusion, its thickness about 3.5 mm. further more, its goes from the larger side of the extrusion to the oposite side. So it is a significant part of the whole extrusion. It certainly adds to the overall solidity of the area. I don't see why plates strongly attached on each side of the mast would not solve the problem. I believe in fact that the overall strength shall be much better. I understand that airplane structures a often repaired this way. The critical point being that the number of rivets, their position is a key element in the solution. The plates would have dimension of 11x 10 inches x 4.5 mm thickness and made of 6005 T6 aluminum.
It is a good idea to consult an expert in structural engineering, altough I do have the maths knowledge to do the calculation, but no experience inthis domaine.

[chris95040]

Originally Posted by Elie

The mast was pulled on its larger side parallele to the ground, the broken side under(in extension), with the weight of the sail.
The in-mast 'extrusion', is in fact part(not welded or attached later) of the whole extrusion, its thickness about 3.5 mm. further more, its goes from the larger side of the extrusion to the oposite side.

Its informative to run euler’s buckling equation on various sections, its not intuitive how little impact things like wall thickness has compared to say overall distance between walls. So maybe your inside extrusion thing helps a lot, maybe it helps a little.

Originally Posted by Elie

I don't see why plates strongly attached on each side of the mast would not solve the problem.

Neither do I, but that doesn’t change the fact that it would be breathtakingly negligent to not consult a domain expert on this repair.

Originally Posted by Elie

It is a good idea to consult an expert in structural engineering

It is.

[Elie]

By the way, My talks with Charleston Spars confirmed that it was a good solution. The only problem was that they don't seems interested in providing the required plates: They don't follow up to provide me with a cost and a date of delivery. Maybe should I call in France(francespar, the owners of Charleston Spars) to solve this issue . Long time ago, I called in France to get a new spreder for a mast, since Charleston Spar was not responding, The next day the new spreader was delivered!...

[Minidude]

This thread has certainly sparked some controversy. I am sure my response will be unpopular with some, but I think your spar is toast. The damage is at an area that must support a spreader? Yes? The forces of compression by the spreader, the standing rigging, and other factors, makes your repair proposal very worrisome. I certainly would not proceed with the direction you are taking.
I find it difficult to believe that Charleston Spars would want to have anything to do with your approach. Maybe that is why you are not getting all the cooperation from them that you desire?
If you do manage to fix this as you propose, please let us know how the repair holds up through the following sailing season. Good luck.

[casual]

Jean Van Daheed has rounded South America heading north in the GGRace . He has a I, believe with a 3 to 5 cm dent tear at the lower spreaders. He says he is sailing gingerly.He states the only good repair is to replace the mast.

[Jesiah]

I'm Canadian too, and putting it through my insurance, so they could deal with the marina's insurance company, would not be affecting my 'canadian integrity.'

If your car fell off a transport truck, are you dealing with the driver in an overly kind, compassionate way? Not likely. It would be a few phone calls and move along. Why not the same with this?
Marinas have insurance for reasons exactly like yours.

[jimbunyard]

Originally Posted by valhalla360

An I-beam is only designed to resist bending in only one direction. The web resists shear force but that tends to be a small stress so it's usually OK to put holes in it (within limits). If you try to bend an I-beam side to side, it tends to be very weak.

In terms of the side to side bending of the mast (as opposed to fore & aft bending), this damage is equivalent to completely removing one of the flanges for a short distance at the highest stress location.

I suggest a structures course to understand why it's likely around 75%. If you don't understand, it would take a few hours to run thru how to calculate it. No I didn't run the calculations so I'm not guaranteeing it to the nearest percent but I guarantee it's well over 50% loss of strength in terms of side to side bending.

Suffice it to say that I don't need an (incomplete and inaccurate) description of how I-beams work.

Nor do I think your 'few hours to run thru how to calculate it' is of much worth; I have literally tens of thousands of hours experience building, repairing and designing structures in many kinds of wood, most commonly used metals, many kinds of plastics, and both synthetic and natural stone.

Given the lack of supporting evidence for your variable, unqualified 'loss of strength', I assume we can use a bastardized Zeno's paradox, and finally come to the conclusion that the mast requires no side at all, hell, really that the OP doesn't even need a mast; he can bend his halyard around one of those newfangled 'sky sheaves' and hoist his main with that...

Originally Posted by chris95040

Somewhere deep down you knew I didn’t mean along the whole height of the mast.

To the OP... Please make sure a (sober) expert looks at that mast.

Remember, although aluminum masts are typically way stronger than necessary for the straight compression loads they are expected to see, their fitness for our purposes comes in part from their ability to withstand buckling failure. I’m no expert but it sure looks to me like that mast would buckle sooner with the majority of one side missing in the damaged area.

Not particularly interested in reading your mind.

Silly ad hominems aside, a closer reading of the relevant posts of the thread might seem in order. Feelings such as 'it sure looks to me' and 'I’m no expert' seem to be singularly out of place in this 'discussion'.

Originally Posted by Elie

When the mas was raised, il was attached by a sling on each (roughly) end of the extrusion. It was heavy, since the main sail was still rollen into the mast. It did not bend nor showed any risk of breaking.
We have to keep in mind that the internal 'tube', solid internal part of the extrusion for the in-mast furler, increases seriouslly the overall strength of the extrusion, obviously. Anyway, in this area(lower spreaders) this is a 4.5x 1.5 in hole for the bar that goes trough the extrusion. So the 'breakage' is less terrible then it looks. And keep in mind that the break occured only on the flat area of the mast, and nothing occured to the front and rear of the(rounded) profile . I'm sure that plates on each side on the break would add to the actual strength of the mast at this place. In fact I'm thinking of doubling also the upper spreaders in the same fashion. Just in case!
By the way thank you all for your positive support of my problem. IT IS GREATLY APPRECIATED!.

Originally Posted by Elie

The mast was pulled on its larger side parallele to the ground, the broken side under(in extension), with the weight of the sail.
The in-mast 'extrusion', is in fact part(not welded or attached later) of the whole extrusion, its thickness about 3.5 mm. further more, its goes from the larger side of the extrusion to the oposite side. So it is a significant part of the whole extrusion. It certainly adds to the overall solidity of the area. I don't see why plates strongly attached on each side of the mast would not solve the problem. I believe in fact that the overall strength shall be much better. I understand that airplane structures a often repaired this way. The critical point being that the number of rivets, their position is a key element in the solution. The plates would have dimension of 11x 10 inches x 4.5 mm thickness and made of 6005 T6 aluminum.
It is a good idea to consult an expert in structural engineering, altough I do have the maths knowledge to do the calculation, but no experience inthis domaine.

Your intuitions are mostly correct, your mast is not 'toast'.

As before, probably the best solution is to either reform the bent piece back into position and weld the tears, or to cut it out completely and weld in an appropriately formed piece of aluminum.

A competent, qualified welder should handle this; the proper amount of heat and, though many people will tell you it isn't necessary in aluminum, back gassing or purging is probably a good idea, since you want to use a lot of heat to ensure complete penetration with no porosity, as well as to avoid heating a larger section of the mast than necessary.

Although the 'internal wall' of the furling section of the mast helps impart a great rigidity to the extrusion, I would be at least a little leery of adding plates to the mast for fear of inducing hard spots, and would certainly not add them anywhere as a 'just in case' precaution, especially if there is some type of apparatus connecting the opposing spreader bases to each other through the mast.

For reference's sake, a cross section of what I assume your mast is like, which will hopefully illustrate to some why the only thing massive about this damage is it's ugliness...

[valhalla360]

Originally Posted by jimbunyard

Suffice it to say that I don't need an (incomplete and inaccurate) description of how I-beams work.

Nor do I think your 'few hours to run thru how to calculate it' is of much worth; I have literally tens of thousands of hours experience building, repairing and designing structures in many kinds of wood, most commonly used metals, many kinds of plastics, and both synthetic and natural stone.

Given the lack of supporting evidence for your variable, unqualified 'loss of strength', I assume we can use a bastardized Zeno's paradox, and finally come to the conclusion that the mast requires no side at all, hell, really that the OP doesn't even need a mast; he can bend his halyard around one of those newfangled 'sky sheaves' and hoist his main with that...

Please let us know where you do your design work so we can avoid those unsafe areas.

If you don't understand how taking out the entire side drastically reduces strength, anything you design is suspect.

[stormalong]

While everyone here is focusing on the mast repair you are missing a very important point. The OP does not want to bother his insurance company.

The boat fell over! The hull could be cracked. The bulkheads could be torn loose. There could be other unseen damage. And obviously the mast is damaged.

This is why the OP paid insurance and he does not want to use it! This boat needs a professional survey before anything else is done. The insurance will pay for it. Take the logical first step and call the insurance company.

[valhalla360]

Originally Posted by stormalong

While everyone here is focusing on the mast repair you are missing a very important point. The OP does not want to bother his insurance company.

The boat fell over! The hull could be cracked. The bulkheads could be torn loose. There could be other unseen damage. And obviously the mast is damaged.

This is why the OP paid insurance and he does not want to use it! This boat needs a professional survey before anything else is done. The insurance will pay for it. Take the logical first step and call the insurance company.

This got covered early in the thread but for some strange reason the OP thinks because he's Canadian he can't use his insurance and shouldn't pursue the marina that dropped the boat.

[stormalong]

Originally Posted by valhalla360

This got covered early in the thread but for some strange reason the OP thinks because he's Canadian he can't use his insurance and shouldn't pursue the marina that dropped the boat.

I know this. The OP is shooting himself in the foot by not contacting his insurance company.