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HighFly_27 10-01-2013 03:59 PM

Mast Life and When to Replace It ?
Boat Info: 1970 Islander 37 M S

I've searched for information but did not find a lot about the method used to evaluate a mast and when to replace it.

My mast has some (2 inches) corrosion at the base but nothing visible up the tube.

I read where racing boats have their mast's replaced due to.... cumulative stress loading. I'm a airplane mechanic and understand why a alum. mast is stain hardened and becomes brittle & fails under heavy load... specifically in a raced boat.

My question is geared against a non raced boat but 43 years old. Logic may dictate.. it may/ should be at the end of it's service life. If I was inspecting it in the airplane world... I'd strip the paint and inspect it for cracks and return it to service if found A Ok. I have the mast off the I-37 and did not see a bending set in the mast.

My reason for asking this question is receive advice, & what others have learned over the years. I understand the saying... if it ain't broke, don't fix it. I'm concerned about sailing in higher wind conditions and my mast fails. I could address the 42 year old mast now and save a much higher $$ expense, should it fail at sea. I was pricing new masts, they run about $ 4 K.

Note, the hull is in good shape, blister/ defect free. A lot of money has been spent on this boat. If I bought a new mast... it would not be throwing money away against a boat that need's everything else to be seaworthy.


Delezynski 10-01-2013 04:20 PM

Re: Mast Life and When to Replace It ?
This may not address your specific question, but.....

We replaced our mast in 2003 about a year we departed to go cruising. At that time it was about 26 years old.

When I was inspecting our mast I saw that the goose neck had been moved and re-welded a bit higher. I found corrosion at the base, and it had a number of holes that were left over from a previous owner mounting something no longer there.

I contacted three yards for a quote on painting it. What I found was the cost to re-pint the mast, IF I DID ALL the prep work, was almost the cost of a new mast!

I did a lot of measurements, specified the height of the goose neck, track on the front of the mast, lights etc..... and got the EXACT mast I wanted. It did away with ALL of our worries.

I would say that it was money well spent. Next, we do replace our rigging, standing and running about every 5 to 7 years.


HighFly_27 10-01-2013 04:34 PM

Re: Mast Life and When to Replace It ?

I think your Replacement Logic is Well Founded.

Is it Ok to ask the cost of your mast and where ? Your a 27 footer and the mast will be smaller, the supplier name would be helpful.

Did you like the quality of the replacement mast ?

Did they have a Warranty, if so, how long in time ?

Email contact --


davidpm 10-01-2013 04:43 PM

Re: Mast Life and When to Replace It ?
These guys have a pretty good reputation:
I have personally only used them to replace a catalina 27 boom.
They are only 30 minutes from me so it was easy.

Delezynski 10-01-2013 04:47 PM

Re: Mast Life and When to Replace It ?

Just sent a PM....:)

Omatako 10-01-2013 07:24 PM

Re: Mast Life and When to Replace It ?
This is just a personal view so don't adjust your set.

A mast generally speaking is not subjected to a huge amount of changing load that would work-harden the material. Most of the load on a mast is a compressive load induced by the stay wires, shrouds. Those same stays, shrouds serve to fully support the mast section and reduce (almost eliminate) any movement.

The side loads on a mast are induced by the luff of the sail in the track and that is supported along the entire length of the mast which does not create localised stress and only localised stress will cause failure. All the side load is borne by the rig (cables). An aircraft is obviously different because wings, elevators, rudders are unsupported and do all the load bearing themselves with the associated flexing and consequently the work-hardening.

As a support argument for this, I once had an inner lower diamond stay bottle screw fail on a mast. The movement on the mast without that stay was something to behold - it was extreme - and there was no movement there when the stay was correctly in place and tensioned.

It is my considered opinion that if the rig is in good shape and correctly set up, the mast section will last for a really long time unless there are obvious signs of corrosion or physical damage.

Whilst it is imprudent to rule it out, in my experience broken masts have always been the result of a stay wire letting go and not the collapse of the mast section. I can't recall seeing a mast fail without a wire breaking first.

Oh, Maybe using an inner baby stay in a lumpy sea without running back stays will cause excessive movement that can cause a mast to collapse but this is probably poor seamanship more than anything.

HighFly_27 10-01-2013 08:07 PM

Re: Mast Life and When to Replace It ?
Mr. Clarke,

Thank You for taking the time to explain things, I buy it.. 100%. I did not think about the difference of a unsupported aircraft component in comparison to a supported sailboat mast. I saw the alum. mast as being loaded & loaded (flexing) and causing metal fatigue of the alum. metal over time.

So, my 42 year old mast should be good... based on one small area of corrosion at the base. I should strip it and repaint it and put it back in service... not to worry. I'm guessing about $ 750.00 for materials.. against $ 4,700 with tax & pick up (370 miles away) at St. Pete., FL.



Waltthesalt 10-01-2013 09:12 PM

Re: Mast Life and When to Replace It ?
sometimes there's a corrosion problem at the mast step due to moisture draining down while the rest of the mast is ok. So cutting of a few inches might be all you need to do. Another issue can be corrosion around the ss fasteners that hold tangs and spreaders. Likewise these can be replaced with a larger screw properly bedded. Then there's spreaders and checking thier integrity. A more critical item is rigging which can have cracking, and crack corrosion. I think by far masts rarely fail in comparison to rigging failures. I'd ask a local rigger to do an assessment.

davidpm 10-01-2013 09:16 PM

Re: Mast Life and When to Replace It ?
And then, wait for it!!


Seriously though.

We have had a lot of discussions about chainplates and indeed it it fairly common to hear of chain plate failure.
They are in a place where they can be loaded and corrode.
My favorite chain plate story was about the guy who replaced his just because they were old even though they looked perfect.
His friend tried to reuse the material from the old plate and in shattered in a shear. It was completely crystallized.

Delezynski 10-01-2013 09:40 PM

Re: Mast Life and When to Replace It ?
GOOD point on chain plates!

I replaced mine late last year. They looked good on the outside. As I was removing one, it broke in half!!! :eek:

Did a Youtube video of the change out.


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