Is this mast weld failing?

[dgadee]

This is the spreader base for an Isomat mast from the 1980s. It is on the compression side (swept back spreaders). I have had the boat for 12 years and only noticed this. On the other side of this same base, it looks as though extra welding has been added along the base length.

Is this just undercutting when the original weld was made? Or is it movement of the base?

It does not look new and does not seem to have a gap along the base. Is there a test or should I just get a layer of weld put on top anyway?

 

[rogerthebodger]

Yes that does look like a crack.

I would have it checked with ultrasonic inspection equipment to see how far th crack goes

 

[Fr J Hackett]

Yes that does look like a crack.

I would have it checked with ultrasonic inspection equipment to see how far th crack goes

Do you think it could be just lack of penetration?

 

[rogerthebodger]

Do you think it could be just lack of penetration?

Could be but it does not look good. The black line does not look like l lack of penetration and it is at the edga of the weld run

This is why I comment further testing to see how far the crack or lack or penetration extends

We need Cliff to comment (haven't seen Cliff for some time)

 

[thinwater]

Nope, don't worry about it. That is what happens when you weld to an anodized spar of a different alloy. In fact, nearly no weld strength is needed, since the load is compression, and most makers bolt or rivet the fitting instead. It is a corrosion effect, not stress, and is not a sign of imminent failure in this application. I see similar lines on refinery equipment welded from mixed aluminum alloys. Not serious in low stress applications.

 

[dgadee]

Brill. Thanks - I was pretty sure it was ok, but you never know.

 

[penberth3]

Brill. Thanks - I was pretty sure it was ok, but you never know.

You could monitor this by applying a few spots of gloss paint across the suspected crack. Movement will crack the paint.

 

[William_H]

OP says the crack is on the compression side of base. ie within the tighter angled side. So no concern. I would disagree. The force of load of cap shrouds on the spreader angle is to push the middle of the mast forward. Hence a force to move the spreader to remove angle back. To remove this force pushing middle of mast forward is to invite mast to crumple middle back. Having lost a mast myself due to failure of the spreader base to maintain angle aft I can only say be careful. I would suggest welding across the crack and further out on the mast surface. All this assuming that it is a fractional rig where spreader sweep back is critical. This may not be the case of course. ol'will

 

[Charlie Boy]

That’s quite a chunky weld, a fair bit of redundancy built in there.

 

[ean_p]

OP says the crack is on the compression side of base. ie within the tighter angled side. So no concern. I would disagree. The force of load of cap shrouds on the spreader angle is to push the middle of the mast forward. Hence a force to move the spreader to remove angle back. To remove this force pushing middle of mast forward is to invite mast to crumple middle back. Having lost a mast myself due to failure of the spreader base to maintain angle aft I can only say be careful. I would suggest welding across the crack and further out on the mast surface. All this assuming that it is a fractional rig where spreader sweep back is critical. This may not be the case of course. ol'will

I don't see a crack, what I see is an undercut weld on the left side of the fitting. I'm thinking that if it were a crack caused by a rotation of the fitting then there should be some deformation around the fitting on the mast wall surface to accommodate that rotation and subsequent crack.