Mast step truss, inevitably:(

[MarkRyan1981]

My surveyor has been down to assess the truss and he has given it a thumbs up, so I can finish glassing the sole back in and bolting the mast foot back in.

So the time has come to start writing up the process, I have started with an explanation of the problem below.

http://www.albinballad.co.uk/about-the- ... ast-truss/

Any suggestions for anything I should add to it?

Peter, Ivan, I hope you don't mind me quoting you? Next I will write up the repair in full from soup to nuts...

[prjacobs]

Mark,
That's great .... quote me all you like. What a great site you're creating for people looking to buy a Ballad, and surveyors who can use the information for assessing a boat's condition. Sharing this kind of first hand experience helps to dispel any hearsay info floating around that may not apply to all Ballads.
Glad you are done with the problem!

[Bob McGovern]

So its out! Eh, I reckon I could have had another two or three seasons out of,... maybe... err

Holy cow, Mark! That's even scarier than our truss. Sorry if this job cost you a season's sailing, but you did the right thing. Nice looking repair, too. Sorry to vanish for the entirety; medical issues have monopolized all our time and energies.

[MarkRyan1981]

Thanks Peter, I need to find some time to write up the fix in full.

Don't I know it Bob, it made my blood run cold when I extracted it. The hull just above the crack right through the hull and just below was 70% split also and looked like it had been that way for some time (the crack was stained with rusty water). So thanks for urging me not to put it off earlier in the year - could have ended very badly. All the best with the medical issues Bob, our thoughts are with you. Let us know when you get back to sorting your truss out sir.

[MarkRyan1981]

I've been emailing another Ballad owner (Ken, who used the old Ballad owners site) to find out about his truss replacement experience. He noted he also had to replace the transverse mild steel beam in the bulkhead forward of the truss! I have sealed mine up completely, so no water or air should be able to reach it, so hopefully it will not rust.

"When I do get back to you I’ll tell you about a follow on problem from the mast foot repair, namely needing to renew the transverse stiffener just forward of the mast which you step over to get to the heads/forepeak."

I think any solution used probably shouldn't bolt through that bulkhead or rely on it structurally.

edit - a bit more information from Ken on the issue:

"Briefly, the beam was a separate project. The mast foot repair solved the bow crack and that worked well. A couple of years later (I think it was just after the YM Triangle Race followed immediately by the Round the Island Race) I found the rigging going slack. I tightened it but very quickly it slacked off again. It soon became apparent that either the mast was going down (it wasn’t) or the chain plates were going up. Effectively the sides of the boat were being pulled up. I stripped out much of the interior, cut into the transverse beam and found another bit of very heavily corroded/disintegrating mild steel encased in the fibreglass. The MS was wing shaped, about 900mm long. My solution was drastic. A sheet of 18mm marine ply cut into 3 much wider wings (c 1800/2000mm) glassed onto the hull and together as a laminated beam. The existing ply bulkhead was bolted to the new beam. I used what was left of the ply to make a couple of smaller bulkheads forward of the heads."

[MarkRyan1981]

Ken managed to dig out the Photos! Full account is here:

http://www.albinballad.co.uk/about-the- ... erse-beam/

Now that IS a big crack, vindicates your decision to extract Bob - does make you wonder about that transverse beam though.

[MarkRyan1981]

Right, the start of the truss write up is here:

http://www.albinballad.co.uk/how-tos/fi ... ast-truss/

With a full explanation of the problem here:

http://www.albinballad.co.uk/about-the- ... ast-truss/

Any and all comments welcome

[dahlke]

I must have been living under a rock I only just came across this thread.

Long story short I had a look at the mast step truss aboard Obelix (#332). I can't see any corrosion above the big blob of thickened resin. I have none of the other signs (visible rust). I wonder why my mast step truss appears to have no corrosion? Of course, I have no idea what state the steel is in inside the big blob of resin but above the blob it looks perfectly fine.

Based on my visual inspection I'm leaning towards not replacing the truss. What would you guys do?

[MarkRyan1981]

Hello Mads,

It looks like Obelix has always been very well loved and never had standing water in her. That truss looks very good indeed! As you rightly say, you can't know what is going on beneath the resin pour, however, if there is any corrosion (and looking at the top of the truss, I would hope there was not) down there, the process of the hull splitting is actually a very slow one and will become apparent long before any failure. The real 'catastrophic' fail point is if that top, visible part of the truss fails as that will fail in a sudden way. I might be tempted to probe your truss with a screw driver as I did, if nothing 'flakes' off, walk away, count your lucky stars, and get sailing.

Triola had a period where she was standing with rain water in her, unloved, the problem manifested itself at that point I think.

I was given some great photos from Shebeen I have published here: http://www.albinballad.co.uk/about-the- ... erse-beam/ - Note her truss didn't LOOK that bad above the resin pour, however, the rusty water gave it away! So you should get plenty of warning if you ever do have the problem (and if no water gets in there ever, you shouldn't!).

I've written up the hull repair here too: http://www.albinballad.co.uk/how-tos/fi ... your-keel/

All the best!

[Bob McGovern]

Good info on the transverse beam, Mark (& Ken). What should we call it -- a clavicle? Ours has some surface rust but lots of sound metal remaining underneath:



After touching up with a wire wheel:



I think we'll just leave it be; the beam is 1/4" (7mm) steel, and we have now joined our main bulkheads and upper beam sandwich to the overhead with epoxy and glass tabbing. The hull is not likely to flex much in that area, even if our clavicle did fail.

Anyhow, our local welder called (out of the blue) to say he'd gone and fabricated the new truss out of stainless steel. I had been leaning more toward Aluminum lately, but he would not know that. So I picked it up yesterday. It is heavier stock than the original mild steel truss and quite a nice bit of work:




Set in place:


Probably will locate and drill it this Autumn, but won't epoxy it into place until Spring. Too much else happening right now. This truss is 316L stainless, a fat 3/16" stock (probably 5mm true dimension). Welder bought a roll of 316 MIG wire just for this; will have other jobs for him. Total cost was $375 US (€340): $200 delivered cost for the steel, and two hours labor.

Mads: your truss looks pretty clean. The lack of corrosion on the machine bolts is a good indicator it hasn't been sitting in salt water. How some Ballads have un-corroded trusses & some look like ours or Mark's is a real mystery. At the very least, every owner should scope their truss, just for peace of mind. The bad ones can be really bad!