Mast failures

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Hi Nonsuch sailors,
I would like to start a thread to collect info on Nonsuch mast failures - I think we all need to be aware. We had one in our weekly Wed night race in Cape Breton this week.

I am trying to help the owner who is not an INA member, to figure out how to deal with this. We have found a salvage aluminum mast, so there is a potential easy solution… i won’t go any farther on this as it is underway with insurance, adjusters and all…

I am interested to know more about other known aluminum mast failures. In my research since my friend’s incident last Wednesday, I found a thread (in our Google discussion group) about a UK owned Nonsuch 30 that had a sudden breakage at deck level, while sailing. Bang, and it was down. No damage or human injury otherwise in either event. (c.2009 I think). In the 2009 incident, insurance company declined to cover, due to fine print: ‘gradual corrosion causing crystallization of the aluminum, due to to contact with Stainless steel clamp that slid off,’… resulting in reduced tension strength… Insurance does not usually cover wear and tear and gradual degradation…etc…

The insurance company cited corrosion of the aluminum due to contact with stainless steel. based on their engineer’s report that cited crystalization indicates reduced tensile strength.

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The failure in the photo here was likely due to unnoticed cracks below the top of the deck ring.

I am not an engineer but I believe that is approximately the location of the maximum bending stress.

If the mast is left installed for extended periods, like on shore over the winter year after year, it will be difficult to see a problem (crack) developing

In the fall of 2000, my Nonsuch 33 suffered a mast failure at the joint. The upper section tore from a bolt hole.

I was fortunate:
The failure occurred on the way to the boatyard for the winter, no injuries to crew.

Towboat US showed up 10 minutes later without invitation (I am a member) and guided us under our own power to a dock where Towboat helped us get the sail off.

I sent the report, photos and estimate for a new carbon fiber mast to my insurance company by email. They replied “okay” 1/2 hours later.

It took over 8 months to get the replacement mast as the designer/builder was transferring the equipment from his place in Concord, MA to the new builder, Moore Brothers in Bristol, RI during COVID.

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Top- Failed mast on arrival at boatyard -Oct 2020
Above- New mast at builder - June 2021
Below - Self transporting on borrowed 8 man rowing shell trailer

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Out of pocket, I happily bought a new sail to fit the new mast bend.

Subsequent to my failure, a 36 at my yard discovered a deck level crack in his mast. As I understand it, after some pleading, his insurance company at least helped him with an aluminum mast replacement. His replacement was from Klacko.

Ward Woodruff
N33 #8 Margery
Niantic Bay, CT

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Hi Greg,
I like your idea of collaborating to accumulate relevant information that would guide our maintenance efforts. Mast & wishbone is an excellent place to start.

My efforts on Soave have been focused on detection and remediation of problem areas, but the effort can be overwhelming. Knowing what I know now, I would approach purchasing a NonSuch differently. Close up inspection of mast and wishbone is necessary to properly assess value because remediation is time consuming and replacement is close to the value of the entire boat.

I’m in the process of purchasing a winter cover and contemplating a $455 option for the flexibility of wintering with mast up or down. I’m seriously considering skipping the option because having the mast down in the winter allows me to see and address many early stage issues. Plus while working on Soave in the yard I could observe the stresses on boats stored with their masts up. A boat in the water moves slightly and heels to dampen the effect of strong wind gusts. On the hard boat doesn’t move and the spars are flapping in the breeze.

Regarding the photos. The failure looks to be in close proximity to the deck collar where the wedges are set. On my NS33 there aren’t any stainless fittings in that vicinity, so I’m thinking the cause of the crystallization would be something other than the effect of dissimilar metal corrosion. Maybe stress fatigue cracks that were missed during inspection.

Rob
s/v SOAVE
NS33 #009
Cedar Point YC
Westport, CT

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Hi All
Studying the picture, I’m curious to know the starting point of the failure. The fact that the mast has the original half moon fairlead collar ( rather than the wrap around style ) indicates an early boat number. It does look like a replacement bottom section (1/4 wall thickness) so that is good.
When we did the mast bottom replacement program, the yards were instructed not to drill through the mast to install the deck pin but rather connect the mast hold down kit supplied. Sadly, some yards did not get the memo. I don’t see the deck pin here in the picture. Another plus. BUT I can’t determine if a hole is not in the mast.
It’s possible everything was done right and no holes in the mast and this is simple fatigue left unchecked by leaving the mast up every year?

Cheers
Mike Quill

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Being a metallurgist, I think the term crystallisation is wrongly applied in terms of the mast failure.

Stainless steel and aluminum galvanic corrosion is often seen in damp areas, especially in salt water environments. During the corrosion process, the aluminum surface oxidises, which is evident as a white powder. Over time the surface becomes rough and pitted. Deep pitting will weaken the mast in that area, and as the mast flexes in normal use, a crack can be initiated. Over time, this tiny crack, known as a fatigue crack, will grow, until the mast fails. The metal in the area did not fail by crystallisation; it become weaker, and susceptible to failure, due to the pitting.

As Mike Quill says, a hole or excessive flexing of the mast, can cause a crack followed by mast failure, This is exactly the same problem as deep pitting; a small crack forms, then grows and brings down the mast.

On a historical note, back in the 1950’s, fatigue cracks were erroneously thought to be caused by the atoms in the metal rearranging themselves into loose crystals, like salt. and becoming very weak.

John Barbour
Nonsuch 26 “Nature”
Toronto

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I don’t have any mast failure info, but in case any 26 owners have a damaged mast, I just came across a mast for a 26. The boat storage place has a NS 26 there that some other members are scavaging parts. There is a mast there. I spoke to the yard owner. He was going to make it a flag pole. That would be a crime. I explained the Nonsuch community. It is in Wilson NY. Anyone interested contact me and I’ll forward his info. I will be putting this info in the INA marketplace but I hope it can stay in this thread since it’s pertinent to the conversation.

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I was talking to Klacko Spars about our masts while ordering a new heel plug last winter. They said they will no longer be making Nonsuch masts. Unless that has changed, then I think we have three options in the future:

  1. Used masts. Unreliable availability and reliability, but much less expensive when you can find one.

  2. Carbon Fiber masts. In a separate posting Bob N. said":
    ”I connected with Composite Engineering a few weeks ago and have been accumulating tools and materials for the job. Ted Van Dusen, the founder there, was a bit hard to reach but extremely helpful. He’s now 80, and has turned over the manufacturing side of his business to Moore Bros Company (https://www.moorebro.co/). So, I guess anyone needing new masts or wishbones should turn to them.”

  3. Aluminum masts. Klacko Spars purchased the “tubes” as they call them from a flagpole company and then build out the masts from there. If one could get the drawings and specifications from Klacko Spars, it should be possible to duplicate that on a custom basis. I contacted one likely looking flagpole company that I found online and asked if they could do it and they said they probably could as long as they had proper drawings and specs. Depending on how much work you do yourself, this may end up more or less expensive than if you could still buy one through KS, but at least you would have an aluminum mast if that is your preference. I’m not saying one is better than the other.

    It seems to me that the INA really should get those drawings and specifications from Klacko Spars before they decide to chuck them out… They probably have digitized everything by now, anyway, but paper copies can be digitized.

    Come to think of it, it seems like it would be smart for the INA to get the same drawings and specs from Composite Engineering, too, if possible. Mainly because having a single source for such a difficult to produce custom part seems risky.

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John, its great to know there is a metallurgist aboard! Thank you for clarifying the matter of oxidation, pitting, fatigue and failure…My comment about the ‘crystallization’ was taken from the 2009 incident, using the insurer’s words, from their response which denied the claim. Seems to raise some questions about the integrity of the insurer.

Greg Silver
Misty Cat 26C #121
Cape Breton

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Hi Mike
Thanks for your reply - as the upper part of the mast is 130’ below sea level now it will be hard to analyze the starting point of the failure. What I know of this boat, which is 30U #236, from the owner: there are two holes through the mast below decks which I assume are for the original pin. He never had a pin. When he got the boat, about 7 years ago, it had a mast hold down ‘stay’ which he says was ‘screwed’ into the mast. He didn’t like that so he removed it. So there was nothing holding the mast down except the wedges and the transverse bolts in the mast step. I do know the boat wintered with its mast up in the first year or few he owned it - that is now not allowed in our marina so mast has been out the past few winters. We don’t know how previous owners managed this.

Greg Silver
Misty Cat 26C #121
Cape Breton

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Brian Godfrey has a great suggestion about the INA trying to get drawings and specs for the aluminum and carbon fiber masts. I’ll undertake to look into that.

By the way, anyone with thoughts about things INA should consider can always drop a note to INA@Nonsuch.org, or click on the CONTACT tab on the www.Nonsuch.org website. Also, one of the neat features of Discourse is that you can tag people to get them notified they’ve been mentioned in a post, which is a nice way to get the attention of people who might be helpful. So, when I type @BobGehrman, I’m asking to Discourse to let the current INA President know he’s being mentioned in this post.

In the meantime, folks might also be interested in material posted on the INA website that bears on mast failures and failure prevention. Under the MEMBERS tab, clicking on the MAINTENANCE tab not only provides the link to free consulting support from Mike Quill. Lower down on that web page, under SPARS & RIGGING TECHNICAL INFO, there are five downloadable documents related to masts. There’s also a brief discussion of some additional issues on page 12 of the New Nonsuch Owners Quick Guide, accessed along with the original owners’ manuals by opening the MEMBERS tab and clicking on MANUALS.

Another nice feature of Discourse is the ability to assemble materials and key discussion thread elements into an advice article. @GregSilver and @Rob , since you’ve expressed interest in pulling together information on this topic, would you be interested in that as a place to put your results? If so, I’m happy to volunteer some of my time to help with that, and ask @jonlewit to consider helping as well.

– Bob

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I ha e always been told that leaving the mast in when on the hard for any extend period is a poor idea. A boat and mast are designed to move together.

It is as mentioned an older mast with several holes near the deck, but no close to the failure. Possibly a defect in the material from the get go.. Maybe a stress event in the distant past.

Mast inspections are a challenge, other visual check and maybe painting blue reviewing liquid in critical areas not much you can do. The mast joint however deserves close inspection as if that join come the least bit loose it will fail and there is a revised attachment method .

As for the older mast with screw in block and sail attachments , maybe they should be up graded to the newer strap configurations.

That said I have need more mast failures on traditional rigs than Nonsuchs’ it a risk for all sailboats.

I think that Klacko has a mast that was never installed in their shop, give Danny a calll

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Mascouche still has her original 1981 mast which was modified when it became clear that one cannot drill into the lower section of the mast. I believe it was found that the lower 10’ should be free of drill holes. All the early Nonsuches were upgraded to having a tie down to replace the pin at deck level. Jorgen Moller and I did replace the bolts at the mast joint with Mike Quills upgrade in 2011. The original fittings were showing wear.

While on a cruise to Whitby, Ont. I was battling the aftermath of a hurricane that produced short steep seas that had the run of Lake Ontario from Rochester. Mascouche was behaving well under the circumstances under a single reef beating to windward. One was very conscious of the “whipping” of the top of the mast. It became too much for the weather vane which flew off. The constant flexing of the mast must eventually fatigue the metal at the deck area. In addition, it makes light air sailing in a swell very annoying. The wishboom tends to rock about spilling what wind there is. I mitigated these issues with the standing gaff rig. The gaff sheet steadies the mast and prevents it from whipping. I see no reason why yachts with standard wishbooms do not add add a backstay. It should add years to the life of the mast. I will leave it to our metallurgists to determine how much longer life one can anticipate. Anyway an inexpensive dyneema backstay should improve the enjoyment of sailing in light airs. Those with boom clearance issues or extended booms might require a bumpkin to provide sufficient clearance for the boom.

An upgrade that should extend mast life would be to replace the heavy aluminium boom with a carbon fiber one.

John Newell
Mascouche 26C1
Toronto

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Photo taken by Doug Farrand on Quetico 30U #368. The “backstay” is actually the gaff sheet which allows the gaff to be trimmed to the breeze at the top of the mast. On Lake Ontario this can be substantially different to what is happening on the water. JN

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Mast failure to comment

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Hello

Hello ,

I rarely contribute but wanted to share my mast failure.

Forever Hours Nonsuch 30 ultra #302 lost her mast at the deck under the mast collar.

The failure appears to have occurred over an extended period of time.the black oxidation shows the failure before the rest gave way .

Insurance only covered half of the replacement (30k of 60k for mast wishbone,sail and rigging).

In hindsight it would have been better to just buy another boat.

John Cousens

Forever Hours 302

Whitby,on

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Very sorry to see this – my sympathies!

I’m guessing from what I can see in the pictures that this was a combination of a failed protective layer between a stainless collar and an aluminum mast, possibly exacerbated by what appear to be several bolt holes or screws?

– Bob

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I like the idea of gathering information about mast failures and gathering specs for the aluminum mast tubes. The specs for the carbon fibre masts maybe a protected trade secret. It costs a lot of money to come up either the design so we might not be able to get that info.

I suspect the frequency of mast failures is no greater for our boats than for stayed rigs although the replacement cost may be greater for us.

I suspect that if we analyze all of the failures we will find metal fatigue alone was not the cause. Improper holes or corrosion probably created a weakness that started the failure process. Removing fittings on the masts and inspecting for signs of problems has long been recommended. In areas where we keep the boat in the water year round the frequency of a complete inspection may not be annual but it should not be once in 20 years. Unless someone can explain why not I think with the mast up we could still loosen the mast collars, slide them out of the way and check for corrosion underneath and make sure the insulation layer between the stainless and aluminum is in good condition.

Holes in the mast should have the edges carefully filed and sanded smooth so that there are no stress points that encourage crack formation. May John B. or Mike Q. can pipe with guidance or directions to articles with recommendations.

Mark Powers La Reina 26C Vancouver, home of year round sailing and salt water corrosion.

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Unless someone else wants to volunteer I can start gathering info from the INA site relating to mast inspections and failures. I will try to collect them into one document. If people want to send their stories, pictures and info to me I can add them as well.

I am out on the boat so it won’t happen until the fall.

Mark Powers

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Mark (@RMP),

I’ll provide some support when you start working on this in the fall.

In addition to the materials on the www.Nonsuch.org website, we might want to see if we can get in touch with Rob Mazza, who used to work with Mark Ellis and is quite knowledgeable about the rig design. He wrote the factory guidance on preparing the boats for offshore sailing, among other things. And, of course,also @mikequill .

Mazza also wrote an article about freestanding rigs for Good Old Boat magazine, copies of which are downloadable from INA website. Here’s a quote from it, which I’ve annotated with italics and bold:

Without question, the Achilles heel of aluminum
freestanding masts has been metal fatigue,
caused by the constant repetition of
alternating loads. Compared to their
stayed counterparts, freestanding masts
are always in motion. With any structure
subject to oscillating loads, be it an aircraft
wing, bridge, or road sign, the ultimate life
of that structure is a function of the loading
experienced, the number of oscillating
cycles encountered, and the stress concen-
trations involved. The higher the loading,
the fewer cycles can be absorbed before
fatigue failure. This inter-relationship
between loading, stress concentrations,
and the number of cycles all has to be taken
into account in designing for fatigue. The
key is to keep the working load below what
is known as the “fatigue limit.” If that is
done, then a long life of well over a million
cycles is pretty well assured.

On a heeled Nonsuch, where the mast is
a cantilever beam in bending, the weather
side of the mast is in tension, while the
leeward side is in compression. When the
boat tacks, the forces reverse. As the mast
pumps in a seaway, the loads fluctuate.
Over time, the sides of the mast alternate
from tension to compression hundreds or
thousands of times depending on how and
how often the boat is used. This is classic
fatigue loading.

Fatigue loading becomes especially
problematic when there are holes drilled in
the lower section of the spar. These holes
introduce stress concentrations—or stress
risers—that can result in fatigue cracks that
then emanate from the holes, especially if
they have rough edges or sharp corners.
A number of early Nonsuch spars failed
due to this problem, with fatigue cracks
emanating from either the hole drilled for
the mast tiedown pin at the mast collar
or from the halyard exit. The fasteners at
the mast splice were another source of
problems, requiring a variety of remedies.

Designers eventually figured out that
the solution to fatigue failures involved
avoiding holes in the mast and ensuring
the mast wall thickness was sufficient to
extend the fatigue limit. It took a while and
involved the redesign and replacement
of a lot of mast lower sections, but now
aluminum freestanding rigs can be assured
of many years of service.

The key questions are whether the cycles Mazza refers to are frequent enough for fatigue to be a factor, or are the primary concerns inspection/detection/remediation of corrosion and cracks from holes?

– Bob

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As I was taught, metal bending and returning is the elastic region. The upper end of the elastic region is “yield”. Beyond yield is the plastic region, much like how a plastic part turns white if bent too far. Beyond the plastic region is failure, self-explanatory. Inside the elastic region, metal lasts a very long time. Corrosion causes local low yield regions by concentrating stress. In normal use a Nonsuch spar never approaches yield. I reef early and often and inspect the mast annually.

Alan & Tracy, NS30C “Corvus” #216, BPYC Toronto

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Very helpful explanation. Thank you, Alan.

– Bob