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39 minutes ago, Bunyip Bluegum said:

I did not contact Corsair about it. My boat has lived at The Multihull Source for many years. Neither Bob nor Ira has suggested that F28 beams would work. I specifically asked Don Wigston that question and he agrees that they would not work.

Perhaps they could work with extensive "remodeling", but it would be a lot of work, probably not worth the effort.

I really do wish you well but you are getting lots of bad counsel here IMHO. The boat is now "outed" because of the F-boats post and the simple reality of that is you will never get fair market value for it even with beams off another F27, never mind professionally repaired existing broken beams, or worse yet a DIY repair.  You have a good and knowledgeable source in Bob and Ira and I would defer to them.  I would be shocked if they were saying anything other then take the totaled insurance check, buy back and then resell (I would bet a Corsair dealer prearrange to buy the boat from you for the parts) the boat from insurance for a small profit, and then use all that cash to simply go buy another used F27.  Now if your boat wasn't insured or not insured for full market value then you are sort of screwed and have to pick the lesser of the evils in terms of a path forward.  But if fully insured this really is a no-brainer (unless Bob or Ira say otherwise... they will have more insight than I).

No disrespect intended or implied but kinda baffled why you are here.  You clearly know and have access to the best counsel you could have.  I can only guess you didn't like their recommendation but I can't imagine why as you have repeatedly acknowledged their well deserved expertise.

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Bob and Ira SELL multihulls, they are SALESMEN, why would they know anything about DESIGNING, BUILDING or REPAIRING them? 

Gee Thanks for dismissing the knowledgable, well meant and FREE advise offered here as bad council - how would you even know if it was or not, do you have any idea whatsoever of the loading, engineering and construction of that beam.

 Thank goodness Bunyip Bluegum did share his misfortune and "out" the inevitable as these boats age - fortunately nobody was hurt. 

Guess What - Insurance companies are in business to make money and they are not stupid. They would certainly "out" this incident so don't be surprised if they decline you coverage after the totalled insurance check gets cashed.

OR those beams could be repaired, certainly stronger than "a nice set of used ones" or better than new - if access can be had to the original drawings and layup details.

 

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Ah - waiting on some magic from an insurance assessor - Good Luck with that one.

His job is to steer the insurance company to fulfill it’s obligation a minimum cost - then the risk analysis team step up  and that’s when either underwriting costs increase or the option disappears for these type and age vessels.

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Last December there was a F27 beam crack (sustained during a long upwind bash in the Pacific) repair thread on the F boat forum that got 47 posts. They were all on topic, and many of them seemed helpful (owner was most grateful, very Japanese of him). A year ago, right after I got my F27, I posted about cracks in one of my float bulkheads around the chainplate, and got exactly zero responses. So OP, you're ahead of me. Either way that forum has to be the best chance for locating a used beam that the dealer network hasn't already heard about.

This incident is a reminder of how much Ian Farrier is missed in the F boat community. I never knew or even spoke with him personally, but from reading many of his forum posts, its hard to imagine that he wouldn't sooner or later personally inspect the OP's boat, advising him on what to do, and explaining what it might mean for the rest of us F27 owners. 

Any experts out there that can chime on whether any insight can be gained on what the layup of a new beam might look like based on IF's procedure for temporary fix of a cracked beam ("F-27 Beam Repair" pdf attached): two layers 18oz knitted cloth with epoxy, six layers 9oz carbon uni-directional, two more layers 18 oz cloth, repeat on bottom side?
crack.JPG.3b169b1ead71e17f355febdfababd494.JPG

 

I came across the "F-27 Features and Options" brochure from August, 1990 (month before my hull) and found this ... "The advanced construction techniques and high safety margins allow a 15 year structural warranty for the hulls, beams, and folding system." So we are now past two complete warranty periods, and thousands or millions of cycles on the beams. It's interesting that if OP's beam failed with a vertical crack across the beam occurring before the horizonal separation of the forward flange (that's definitely an "if"), then it was in about the same location as shown in the Repair doc. Should this be the primary area of concern of the rest of us, esp for boats that have already had the flange bolts and screws added? Maybe the owner wanting to reduce risk could could get away with pre-emptively reinforcing just this area as described in the Repair doc? Wouldn't have to fuss with the folding mechanism that way.

boardhead is of same mind as Farrier on this point. A poster on the F boat forum wrote "fixed her issue by grinding down the outer flaps and completely wrapping the beam as the ultimate fix. I had brought this up with IF and he said something like...that's the thing to do if you don't want to worry about it again".
  
However boardhead you do the Corsair dealers a disservice when you call them salemen alone. They are a lot more than that and I think most in the F boat community agree.

The last sentence of the Repair doc says "replace with a new beam", something that was possible when the doc was written. IF also posted "home built beams use the exact same specifications as the production beams, but being flangeless there has never had a failure, but they are also very time consuming (expensive) to build." So I can offer you this OP. If, as suggested earlier, you can find a small company willing to set up an F27 beam production operation, I would gladly contribute $100 to them via a Kickstarter, if it means I might someday have the ability to buy a new replacement beam I hope to never need. Can you find another 100 F27 owners? Have no idea if that would make a dent in set up costs. 200 owners? $200? This is pretty much the opposite of just taking the insurance check and buying another F27, but it would be doing all of us a great service ;) 

Again, good luck getting back on the water.

F-27 Beam Repair.pdf

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I build my beams with carbon (no glas) for my F32. It was the project I started the build of my F32 because of the limited space needed. I finished them in one year inclusive sailing and racing on my other boat during the summer. The cost were a +/- 5000 Euro on material and that was for special strong beams for foils in the floats.
The weight is 26 kg a piece, I think for the F27 they can be lighter.

I think if you can make a mother mold from the remaining beams you can build quicker and I can give you the laminating scheme of the F32 and how to build them.

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  • 4 months later...

At this time, I have acquired a forward beam. I have located a rear beam, but don't actually have it yet. The repair plan is to just replace the beams.

The surveyor said it was "fatigue failure", and therefore it is not covered by insurance because they say that is "normal wear and tear".

I don't quite understand how a foam core composite structure fails from "fatigue". Neither I nor anyone I know has ever heard of this happening on any other F-boat.

If fatigue is a legitimate "thing", I wonder if I should be concerned about a similar occurrence on the starboard side.

Thanks to everyone for all the information supplied here. It has given me some insight and external perspective into this highly unusual event.

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I don't quite understand how a foam core composite structure fails from "fatigue". Neither I nor anyone I know has ever heard of this happening on any other F-boat.

I though beam delam was a common thing.....   I've repaired one.

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Yeah that's bullshit on the surveyor. Tell him how he knows it's fatigue and not a latent defect in the F-27 beam construction... oh wait.

Unfortunately latent defects are not covered either. It sure looked like the beam failed due to the pieces separating due to a latent defect.

Fiberglass does fatigue. It's a known thing. CF is much better for fatigue properties. But I do not know of a way of determining fatigue in composite structures. Just not my area of expertise. It's easy to tell in metals.

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You may want to look on homebuild glider and aircraft forums, it’s long been known about fatigue failure with composites, but when I stopped gliding back in the early noughties that learning curve of when to sign an aircraft as beyond its fatigue limits, the glass and carbon aircraft time limits were simply being extended by often 3K hours as there were no failures.
 

Perhaps you could do a bit of “foruming” and ask a few questions as there’s some really talented builders and designers that are 20 years of track ahead of the likes of the Farriers.

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21 hours ago, Bunyip Bluegum said:

I don't quite understand how a foam core composite structure fails from "fatigue".

I used to work in fatigue test at a major Connecticut helicopter manufacturer.  We definitely did fatigue testing of composite coupons and parts.  The S-N curves are a lot different than metal.  

No idea if your beam failure was fatigue or something else.

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I think the fatigue issue is obvious if the beam had blow foam in it to stop oil canning. Do they then rely on the waterlogged foam in later years?
IMHO structural foam glassed into the laminate would have stopped this thread from existing?

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My guess is that a fatigue failure is highly unlikely. The paper that MultiThom posted clearly shows that, if you design in enough safety margin, fatigue limited strength bottoms out at around 1M cycles. The quality of the bonding material is very important though. As Wayne wrote, production gliders have their fatigue life continually upgraded. Most older gliders to 12000 flight hours now. Design limit of a glider is generally 5.3G, with added safety factor, while a glider in normal use hardly ever is loaded more than 2G. Factor in 2 landings per flight hour and you are way below 1M cycles.
 

The beams that Ian designed are quite strong. He did however acknowledge that production beams sometimes have issues as the beams are basically two halves, glued together. One glitch in the glue line can cause delamination problems ( which are virtually non existent in home build beams ) and this can cause a crack to grow over time. When sailing with production beams a periodic inspection is not a bad idea.

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I *think* airplanes/gliders are actually easier to design than boats in some ways. Much more weight sensitive but the LOADS are often well understood.

Boats jumping up and down in waves puts loads on hulls and beams that are very variable.  It's one thing to design for the fatigue strength of glass if you know the stresses but you really don't. And the load spectrum is all over the place. Best you can do is guess.

But in this case I agree; it wasn't fatigue. It was a build method that had some variability and future problems down the road.

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11 hours ago, Zonker said:

I *think* airplanes/gliders are actually easier to design than boats in some ways. Much more weight sensitive but the LOADS are often well understood.

Boats jumping up and down in waves puts loads on hulls and beams that are very variable.  It's one thing to design for the fatigue strength of glass if you know the stresses but you really don't. And the load spectrum is all over the place. Best you can do is guess.

But in this case I agree; it wasn't fatigue. It was a build method that had some variability and future problems down the road.

Hi Zonker
Can you elighten me, re a structural failure years down the road but its not classed as fatigue? (assuming the boat didnt do something its not done before)?
Or are we saying it was design that was at 99% for years then it went to 101% load?
Polyester is not as stiff when old as new, is that an issue?

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23 hours ago, Zonker said:

I *think* airplanes/gliders are actually easier to design than boats in some ways. Much more weight sensitive but the LOADS are often well understood.

 

I used to work at Schweizer, well after they stopped making gliders.  For light aircraft, you mostly design for static loads with margin.  When you make them stout the fatigue loads are usually small in comparison. 

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12 hours ago, Sailabout said:

Can you elighten me, re a structural failure years down the road but its not classed as fatigue? (assuming the boat didnt do something its not done before)?
Or are we saying it was design that was at 99% for years then it went to 101% load?
Polyester is not as stiff when old as new, is that an issue?

I guess I'd say it wasn't a "classic" structural fatigue. 

I had thought this failure was one that started when the glue joint separating the upper and lower halves of the beam failed. The glue joint probably didn't fail due to fatigue (which is long term structural damage where a material gets weaker and weaker). The glue bond failed and because the seam is near the neutral axis of the beam (where you have neither tension or compression, just shearing forces), the glue joint doesn't have to be very strong.

I don't know why the glue joint failed (enviromental degradation/wasn't quite right at the factory etc etc) - but it probably wasn't fatigue.

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Thermal expansion and contraction, possible (even soft) collision damage, crystalline salt and also ice action gnaw away at any flaws or cracks which develop particularly as the resin ages and becomes more brittle. 

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I would ask WHO'S SURVEYOR the corpRATS  ?

PERHAPS ONE PAID BY YOU WOULD DIFFER ?

I would defiantly question the mans multi sailing and CF experience

BUT ALSO THINK THE BOLTS ARE AN UNTOLD STORY 

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