dodgy mast?

No not really lots of masts are joined mid way on bigger boats... mines rivited 2/3rd up... if your worrid fill the holes with rivits.
 
Nothing is wrong with this mast structurally. It will be good to carry out a local repair to fill the holes and protect the metal. Even if it the holes where half way up the mast, still would have no reason to be allarmed, provided there were no cracks around the holes.
 
Its deck mounted so primarily in compression.

The missing paint makes things look worse in the picture but that may be more cosmetic than anything at this stage.

It certainly doesn't look well and carefully looked after.

There appears to be corrosion around the other fittings. Time to remove the fittings examine things closely and repaint at a minimum?

How well can you examine it internally? The holes would be better sealed with rivets or similar isolating dissimilar metals with Duralac.
 
I'm currently in the midst of dealing with a similar situation on my mast. Lots of hardware near the base, around most of which the paint was bubbling for an inch or two, probably due to galvanic action of the stainless screws on the aluminium. Plus there are a few old, now unused holes.

So far, I've took all the hardware off and rubbed down all of the paint where it was corroded. The pitting underneath is minimal, despite the paint bubbling being much worse than the areas shown in your photo. It'll be coated with some MIL spec al primer before a high build primer and painting with an LP paint. Wehn that's done, all the hardware will go back on with backing pads and several coats of duralac.

Ideally, I'd have the mast out and do the whole thing, but the rest seems OK, so I'm only doing the base this time. I aim do the whole thing when the mast comes out for new standing rigging in a few years time.

I think dealing with such corrosion is just part of the course with painted spars - mine were last painted 15 years ago and the hardware has not been rebedded since then.
 
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As a structural engineer I would be slightly concerned. The mast is fixed at the base and therefore the highest bending moment occurs at the base. Filling with rivets or other material will not replace the amount of metal removed I'm afraid. The loads on a mast can be quite large at times.
 
ghostlymoron said:
As a structural engineer I would be slightly concerned. The mast is fixed at the base and therefore the highest bending moment occurs at the base. Filling with rivets or other material will not replace the amount of metal removed I'm afraid. The loads on a mast can be quite large at times.
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I am NOT a structural engineer, so I can't really argue. The forces at the base I would have thought would be mainly compression, whilst in the middle they would be compression and more laterally.
 
ghostlymoron said:
As a structural engineer I would be slightly concerned. The mast is fixed at the base and therefore the highest bending moment occurs at the base. Filling with rivets or other material will not replace the amount of metal removed I'm afraid. The loads on a mast can be quite large at times.
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Even with the holes drilled in it the mast would appear to have more resistance to bending than its baseplate which looks like it would buckle first.
 
I wouldnt feel too worried tho filling the holes isnt going to change the strength, only the appearance. Agree almost completely compression forces at the base.
 
ghostlymoron said:
The mast is fixed at the base and therefore the highest bending moment occurs at the base.
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I would have thought the greatest bending moment would be between the lower shroud hounds and the cap. Plus maybe a second set of spreaders if there are any.

What do I know. I claim no specialist knowledge.
 
Mast integrity

ghostlymoron said:
As a structural engineer I would be slightly concerned. The mast is fixed at the base and therefore the highest bending moment occurs at the base. Filling with rivets or other material will not replace the amount of metal removed I'm afraid. The loads on a mast can be quite large at times.
Click to expand...

Well that is the thing the mast is not fixed at the base it is merely located laterally at the base so no bending moment only compression.

I had a similar problem with a mast (smaller boat) where three turning sheave boxes had been fitted at the bottom around the base and after time the holes got bigger with corrosion. In the end the mast crumpled to the extent that a bulge appeared in the front where metal was OK and the mast shortened itself by about 1 cm. I eventually repaired it with a sleeve over the base and I went to halyard exits up higher and staggered in height and location.

So in my case even with failure it was a non event. If you are concerned I would suggest a patch over the area of concern. Epoxy and rivet it in place. good luck olewill
 
If it's only a pinned support i.e. free to rotate at the base I would agree that the BMs will be low. However my mast is only free to rotate fore and aft but restrained side to side so could experience bending in that direction. I have seen masts fail in bending at the base but agree that it is more common to fail at the hounds.
 
with the exception

Chris_Robb said:
I don't think I would be worried. It is right at one end of the mast. I would be more woried if it was in the middle, but there is little bending potential at the foot.
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of a keel stepped mast (which the one in the photograph isn't). It would have been sensible to passivate the holes when the old fittings were taken off - I'd be a little concerned about the long-term effect of corrosion.
 
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