There’s a crack in my mast

[LalaSS34]

Hi all

New to the forum and currently working on my first boat - a Sparkman Stephens 34 that’s already double circumnavigated but is very much stuck on concrete at the moment

Upon getting the mast down I’ve noticed an ominous looking crack at the base

Looking into getting it welded, but how critical would you say it is?

[Jammer]

The conservative answer is that the mast should be replaced due to its age, condition, and service history. Depending on your circumstances and your goals for the boat that may not be feasible.


The corrosion on the bottom few feet are as troubling as the crack. If you are not going to replace the mast section, then you might at least consider a sleeve over the bottom few feet, enough to get past the corroded area, and perhaps above the deck as this is where stresses will be highest.

[boatpoker]

Originally Posted by Jammer

The conservative answer is that the mast should be replaced due to its age, condition, and service history. Depending on your circumstances and your goals for the boat that may not be feasible.


The corrosion on the bottom few feet are as troubling as the crack. If you are not going to replace the mast section, then you might at least consider a sleeve over the bottom few feet, enough to get past the corroded area, and perhaps above the deck as this is where stresses will be highest.

Pretty much agree but getting a long enough sleeve in there will be tough, the sleeve has to go way past the corrosion ... even then it's iffy.

[LalaSS34]

many thanks for your speedy replies

Yes a replacement won’t be possible for a season or two at least, due to budget and location (Malaysia) so need a mid term solution

• A sleeve will be difficult to fit in given how the mast is deck stepped, do you think there is potential given these pics?
• Otherwise welding but have heard it can damage the mast?

[Wotname]

Not only deck stepped but pivoting too. Was this a Perth WA boat?

[LalaSS34]

Freemantle I believe yes

[Tin Tin]

Don't see why a sleeve is not possible, what does it matter if it is deck stepped? That alloy may be so stuffed a weld will not stick. One temporary option may be to wrap in carbon fiber and epoxy a sleeve on to it, but would I bet my life on it - no.

[SailingHarmonie]

Am I missing something?

Corrosion aside, which might or might not be significant…. What does that crack matter? The loads are all taken by the pin in the tabernacle. The bottom of the mast is not carrying any load at all of any kind. That bottom plate is just there to maintain the shape of the bottom of the extrusion.

Or am I missing something? (Entirely possible…)

I’d certainly want to get a look inside, especially near and above to pin, to evaluate corrosion. What I see on the surface doesn’t look bad, but that crack does tell me there might be ugly things inside.

But I would not sail across an ocean on a stranger’s internet opinion based on three photographs. Neither would I junk the mast for the same reason…

[hpeer]

Deck stepped mast. My thoughts. These masts have a heavier cross section than keel stepped and are more rigid. The lower end of the mast needs some way to pivot on the deck so that the rake can be adjusted. This can be done with:
A curves bottom shoe that sits on the deck or
A bottom pin that allows the mast to pivot.

Your mast appears to have BOTH.

As said above it is dangerous to make recommendations off some internet pics, but it is what we have. So with those caveats in mind, this old geezer would not worry about the bottom plate assuming the mast is not actually sitting on it anyway.

The corrosion is troubling. However masts are routinely sleeved and spliced with (monel?) pop rivets. I would look to find an ild mast for donor material to make a temporary sleeve. Baring that I would look for local shop which can provide some aluminum plate that could be formed to the curvature. It would be a temporary expedient.

Because of the tabernacle and pin arrangement the sleeve would need to be on the inside. I am presuming the mast is down? And that will make any sleeve even more of a challenge as it will need to be slotted to slip around the pin. Perhaps 2 plates, either side of the pin, welded with cross bracing. Sounds ugly.

Only you can evaluate what resources are available and how much risk you can stomach.

Best of luck.

[MicHughV]

Is that a crack or a broken weld ?
The bottom of the mast appears to have shoe on it, ie, a bottom plate, and this would have to be attached to the mast by some means.

Secondly, the corrosion and pitting seems to occur below the pivot point, suggesting it was caused by the mast rubbing up against the tabernacle and not necessarily integral to the mast strength.

Just musing about this problem.....

[bil56]

a lot of corrosion on this mast ...
in photo n°3, isnt it a copper insert for the axis ?

[psk125]

Originally Posted by hpeer

Deck stepped mast.
Because of the tabernacle and pin arrangement the sleeve would need to be on the inside. I am presuming the mast is down? And that will make any sleeve even more of a challenge as it will need to be slotted to slip around the pin. Perhaps 2 plates, either side of the pin, welded with cross bracing. Sounds ugly.

Only you can evaluate what resources are available and how much risk you can stomach.

Best of luck.

Seems to make sense. Can't sleeve be inserted and then drilled for the pin? Why is a slot necessary?

[hpeer]

Originally Posted by MicHughV

Is that a crack or a broken weld ?
The bottom of the mast appears to have shoe on it, ie, a bottom plate, and this would have to be attached to the mast by some means.

Secondly, the corrosion and pitting seems to occur below the pivot point, suggesting it was caused by the mast rubbing up against the tabernacle and not necessarily integral to the mast strength.

Just musing about this problem.....

The mast on my big bot had a shoe. It was not attached to the mast but just slid in a bit.

Maybe it was welded, I don’t know. Just that I have seen other.

[hpeer]

Originally Posted by psk125

Seems to make sense. Can't sleeve be inserted and then drilled for the pin? Why is a slot necessary?

I was assuming, perhaps wrongly, there was a tube or bushing inside the mast.

Something more than just a hole in the mast. My 33’er has a tube.

I hat puzzles me is why BOTH a pin and a shoe? Unless the ahoe was alowed to slide. But that seems odd.

[Wotname]

^^ The pin (and tabernacle) is there to allow the mast to be dropped (pivoted back) almost to deck level using a couple spinnaker poles (as a 'A' frame) and block and tackle attached to the forestay.

It is very common arrangement for boats based in Perth Western Australia as there are several low bridges that you need to pass under to get to and from the Swan river to the ocean. With some practice and a good crew, the mast can be lowered and raised again in a matter of minutes while underway.