Hairline Crack on Aluminum Mast

[kevin7500]

Aluminum isn't some mystery material to weld. Finding a capable welder/fabricator should be relatively simple. Personally, I would cut it out and build an Aluminum riser out of billet. The material should cost a couple hundred bucks and having a machine shop mill it to spec should be about the same. All included, less than $500 and a bullet proof repair.

[WebSurfer3000]

Hi all
when I mentioned that aluminum weld is out of the picture is because of what I read in the forums. Many people seem to say that welding aluminum will affect the structural integrity of the mast and it would be dangerous as the mast is around 45 ft.

[JiffyLube]

Originally Posted by hellosailor

Assuming you are also on Cyprus so you can actually interview some local fabricators, you might want to try some yacht repair yards or some welding fabricators who are familiar with aluminum.

I would think the least expensive and most praactical (strong) repair would be to cut off the bad part of the base, 4 to 6 inches? And then remove the "key" that was set in to the mast to hold it in the deck step. Then reinstall that "key" in the base of the mast, and raise the deck step itself by putting a 4 to 6 inch thick plate (block) under it, through-bolting the deck step to the extension and through the cabin top, with a reinfocring plate under it. That should be as strong as the original and require minimal custom work, just making the holes in the block and giving it a suitable shape so it isn't ugly.

The block could be any suitable material, ultra-high-density polythene (UHDPE), or metal alloy, or a block of fiberglass, even aa suitable wood block. If you find a fabricator who is comfortable with the job they will probably make the choice based on what is locally available. No "collar" would be needed in that arrangement, since th original mast would still be keyed in the original mast step, and the block under that would be held by compression as well as by the longer bolts.

I think I like this idea the best.

[WebSurfer3000]

Thank you all.
I think this is the most cost effecting solution as well.
When I'm done --- any solution --- I will post some pictures.

Cheers

[PAR]

Yep, cut the bottom of the mast off, clean the step, then reinstall. Naturally step the mast on a newly made shoe that lifts the mast, step and all, off the deck the amount you removed from the mast. It could be welded without too much concern, but it's likely, as has been mentioned, that the corrosion issues have had it's way for too long with the extrusion, which is why cutting it off and starting fresh is the best option, besides, you're likely going to have to peel the mast off that step.

[WebSurfer3000]

Hi all
I already cut off the bottom of the mast and I'm in the process of choosing a competent welder/fabricator for the best price.

Something I like to know. Should the new mast step be off marine grade aluminum or regular aluminum would just do the job? Besides, we have here 6 mm or 8 mm thickness, what is best?
Two different welders gave me different prices the one with marine grade 200 Euros more than the price the other welder with regular aluminum.

As far as I been told The base of the mast does not exert much pressure.

Any advise?


I will soon post some picture of the progress.

Thanks all
Best Regards
George

[motion30]

Welding can b done but will comprise the strength When aluminum is welded depending on the alloy it is weakend With 6061 t6 alloy (the most common ) The t6 is the heat treat number The heat from welding kills the heat treating in that area and softens the alloy There are alloys that are strain hardened and lose much less strength but how do you know what you have?

[motion30]

Alloy 5052 h112 would be a good choice if you can find it If you have to use 6061 t6 use as thick of a plate as practical

[WebSurfer3000]

Hi,
Sorry a misunderstanding. I should have been more clear.
I have already cutoff about 15 cm of the base of the mast with the crack. I’m referring to the new mast step rice of the same size that I’m planning to create. I’m planning to have an aluminum fabricator make me a new mast step that will have a height of 15 cm , the same height as the peace I already cut from the base of the mast. I was just referring to the type of the aluminum metal that I should use as the marine grade one was 200 Euros more that the plane one of the same thickness.

Best Regards
George

[SailFastTri]

Originally Posted by WebSurfer3000

As far as I been told The base of the mast does not exert much pressure.

Best Regards
George

George whoever told you that doesn't understand what he's talking about. Side-pressures might not be so great -- but: The base of a deck-stepped mast is under thousands of pounds of compression load -- at times tens of thousands. That's why (structurally) there MUST be a vertical "compression post" or bulkhead directly beneath the mast.

The mast base must be able to resist the downward pressure of ALL the stresses of the rigging combined, plus the weight of the total rig and sails.

[WebSurfer3000]

Thanks all,
I found it strange as well when that marina welder told me that the base of the mast does not get much preassure.
So I guess that means marine grade aluminum!!!

Best regards
George

[SailFastTri]

Originally Posted by WebSurfer3000

Thanks all,
I found it strange as well when that marina welder told me that the base of the mast does not get much preassure.
So I guess that means marine grade aluminum!!!

Best regards
George

I don't know about metals, and not sure what makes "marine grade" (assume it has to do with corrosion) but all else equal I would lean toward someone who has a better understanding of the mechanical situation.

[Mare Nostrum]

Hi WebSurfer3000,
I hope that you were able to satisfactorily fix your mast.
We also have a hairline on our aluminum mast...I was wondering if you indeed welded or what action you might suggest.

many thanks,
s/v Mare Nostrum
Acapulco