Mast step truss, inevitably:(

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Sanlen
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Re: Mast step truss, inevitably:(

Post by Sanlen » Sun Mar 09, 2014 5:00 pm

Bob McGovern wrote:You shall have to change the name of the RJ-85 to Polymer. :lol: We also own a Buccaneer18 racing dinghy, sadly neglected. Together they are Grannia, Diarmuid, and Fionn. It's nice to have the entire love triangle, but three sailboats is one too many.
Great names! Monomer is the original name from 1978. I always keep the name or change it back to original (if it can be found) sInce I am little superstitious about boatnames :roll:
Best regards,
Jan
#547 Sanlen
Owner since 1993

Bob McGovern
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Re: Mast step truss, inevitably:(

Post by Bob McGovern » Fri May 23, 2014 4:02 pm

Wheee. I've pulled out the suspect mast step truss. Tried an air impact hammer, which was useful for cleaning up the sides, but ultimately it came down to a 3# sledge hammer & some driving points & chisels. If you lack chisels long enuf, a simple length of mild steel 1" x 3/16" bar stock can be ground down & the tip (only the tip!) heat-tempered & does a fine job, with periodic re-sharpenings. The extraction took about 2.5 hours split over 2 days. Here is the truss:
Image
Image
The metal has thinned or eroded completely at the line where water sat on top of the polyester fill. Perhaps most worrisome is the complete disappearance of the lateral stabilizing fins at that level, no doubt accelerated by fatigue & stress riser formation.

Failure was not too far off, I think. And while the mast might not have plunged thru the boat bottom, the foot could certainly have begun thrashing around the cabin -- causing untold damage, possible injury, and probable rig loss. :shock: I will take this truss and a plywood version of a replacement around to a couple of welders & see if any of them can fabricate one in stainless or aluminum. If not, I think oak and/or phenolic plate is the way forward.

If you have never inspected this item on your Ballad, I urge you to do so at the earliest opportunity. Ours seems to have lived most of its life in cold fresh water, with half the year spent on land. Yet this important structural part was near death.
Last edited by Bob McGovern on Fri May 23, 2014 6:08 pm, edited 1 time in total.

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prjacobs
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Re: Mast step truss, inevitably:(

Post by prjacobs » Fri May 23, 2014 4:19 pm

Bob,
That's quite a shock ... so how would one inspect the step without a lot of demolition work?

Bob McGovern
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Re: Mast step truss, inevitably:(

Post by Bob McGovern » Fri May 23, 2014 6:31 pm

prjacobs wrote:Bob,
That's quite a shock ... so how would one inspect the step without a lot of demolition work?
Yeah, I was expecting some thinning, some swelling, but not quite to this extent. BTW, the bolts attaching this strut to the main bulkhead are stainless and in good shape; the nuts are mild steel and have lost almost half their metal to corrosion. Couldn't even put a wrench on them.

Can you get your hands on an aperture camera? The kind contractors and home inspectors use to peer inside wall cavities and heat ducts? Harbor Freight has them for ~$90:

http://www.harborfreight.com/digital-in ... 67979.html

Maybe a builder friend or tool rental place? Some hardware & auto parts stores have rental tools, too. That would be the least-invasive way to inspect. A 2" hole saw, flashlight, and dental mirror may work also. If you search eBay or Amazon.com for inspection camera or endoscope or borescope, you'll find lots of options as low as $11 for a scope that plugs into a laptop USB drive. I'm sure the last thing you want to do right now is tear into Bennath's guts. :| Hopefully your boat has a later iteration of this truss.

Ivan Christiansen
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Re: Mast step truss, inevitably:(

Post by Ivan Christiansen » Sat Jun 28, 2014 12:29 pm

Bob McGovern wrote:After months of patiently spraying the SS machine screws on the mast step plate and tapping with an impact driver, I got nasty today and drilled the screws right out. I wanted to inspect the mast step truss, which many people have had corrosion issues with. This is what I found:
Image
Okay, that has to come out.:( I've reviewed Temptress' photos on the Knowledge Exchange but still have a few questions. Is the entire cavity around the truss filled with thickened resin? Or is it just one layer near the top & hollow beneath?

What have other Ballad owners used to fabricate a replacement truss? Stainless steel? Aluminum? I'd really like to use composite if possible, just so corrosion or galvanic welding would never, ever be a problem again. Do you think a box section or I-beam design would be better than the odd, stepped gussets of the original?
Hi Bob, and everybody else
I am the happy owner of Ballad hull number 5
I had the frightening experience, my mast step support completely collapsed during sailing in quite bad weather and rough seas. The front of the keel could not handle the pressure and as a result of that water came in to the boat trough tiny cracks at the front of the keel.
I had the boat cut open (a very big opening, you could actually go into the boat through the opening) and tock the mast step support out in several tiny bits. I had a new one made I stainless steel and then rebuild the entire area including the front of the keel. I had professionals to do the job.
This was 13 years ago, and I did speak to several Ballad ovners at the time, and even the Danish Ballad club, and try to tell the story, but no one would listen to me and just told me that this was only my Ballad that was build that way, and all others Ballad was fine.
Today we had seen quite a few boats with these problems in Denmark, and some of them with high hull numbers, but most not as dramatic. And I now for a fact that all Ballads build by Albin in Sweden is build that way.
Some is trying to rebuild without removing the entire support, I do not know how those boats are sailing. For my part, it was like having a completely different boat, the stiffness were back, and the boat is still sailing and is sailing good.
Feel free to write if you have questions.
Best regards
Ivan

juhapaas
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Re: Mast step truss, inevitably:(

Post by juhapaas » Fri Aug 15, 2014 12:34 pm

Edit: post removed
Last edited by juhapaas on Thu Sep 18, 2014 7:40 am, edited 1 time in total.

MarkRyan1981
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Re: Mast step truss, inevitably:(

Post by MarkRyan1981 » Tue Sep 02, 2014 10:17 am

Hello Bob,

Cracking post, thanks for sharing. Our Ballad is #50, so based on your experience, I have some concern about my mast step - it appears solid, no rusty water, movement, cracking or sagging or anything like that, what made you suspect yours? Any suggestions for how to test it with an endoscope and where to drill the inspection hole?

Image

Mine is above, we have a 2 year old and another on the way, so we will be doing no wild bouncing sailing for a few years, however we have had her out in forty knots plus in the past and she has remained solid (even with a bit too much canvas up! :D ).

Thanks ,

Mark

Bob McGovern
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Re: Mast step truss, inevitably:(

Post by Bob McGovern » Tue Sep 02, 2014 4:00 pm

Congratulations on the impending nipper, Mark.:) Anywhere right around the base of the GRP 'cap' should give you access to the truss cavity. You can see in the photo of the truss with the cap cut off there is a large hole drilled near the stbd corner. I did a simple visual evaluation thru that & saw enough rust flakes to carry on with the dissection. If using an endoscope with its own LED light, you could drill a much smaller hole. The top of the truss is roughly level with the cabin sole; then there's a thick layer of putty; then the GRP sole; then the mast step plate. You might also get at it from the bilge compartment behind the truss, through the thin bulkhead there. Would spare you a hole in your floor. :oops: We knew major cabin sole surgery was in prospect anyhow, so I was not worried about marring it.

FWIW, there were few visual clues our truss was corroding to this dangerous level. Only stories like Ivan's, and a few documented overhauls by other Ballad owners. We can see, on the front edge of the keel, a few spots of iron oxide peeking thru the bottom paint, just about level with the bottom of the truss cavity. I suspect that was standing rusty water moving thru the laminates & reacting with the copper. You wouldn't notice it nor guess its source if you weren't looking for it. Will get a photo or two today, of the rust spots and a prototype replacement truss. I've found a welder who is willing to fabricate a new one. We are leaning toward aluminum, perhaps as thick as 5/16" (8mm). We'll likely add a few layers of biaxial cloth to shore up the keel structure just in front of the truss foot -- just in case years of water have weakened the GRP.

Bob McGovern
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Re: Mast step truss, inevitably:(

Post by Bob McGovern » Tue Sep 02, 2014 9:39 pm

Measured down from the hull/keel transition, some blisters/weeping that sure look like rust stains and may be connected to the rotting truss:

Image

Peek-a-boo, light shows thru:

Image

Prototype new truss:

Image

The foot is larger for more bearing surface; angles are better; extra lateral stabilizers; and the truss reaches all the way back to the bilge divider/bulkhead, to which it will be attached for extra stability. It won't be poured into a block of polyester resin like the original! When we've got the real thing made up, I will put together a measured diagram so anyone interested could fabricate a replacement truss in advance, saving downtime. If you had a replacement in hand, the changeover could be done in two days.

MarkRyan1981
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Re: Mast step truss, inevitably:(

Post by MarkRyan1981 » Wed Sep 03, 2014 9:04 am

Thanks Bob, we are breeding our own crew! Thanks for the photos, I don't get any shadows or bubbles coming through on the front of the keel although that may be hidden by our coppercoat. It looks a pretty drastic surgery, although a lot less drastic than ending up with a hole in your hull at the front of the keel!

What does the foot of the truss sit on at its lowest extremity, the keel moulding? The actual lead of the keel? And you say you would not fill the area again with resin, I suppose the resin would have served no structural purpose to distribute forces of the rig to the hull? It'd certainly make inspection of it easier! Would you effectively make it another part of the bilge then and put another bit of saloon sole over the top of it? So many questions! :D

As you say, a schematic of the replacement would be cracking and documentation of the steps you go through to complete the replacement would make the job a little less daunting and be a great asset to the Ballad community as a whole.

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