Testing/reglueing 40 years old mast

[germanreader]

Being a long time reader of this forum, this is my first thread:
Our sitika spruce box section mast is 40 years old now. Glue ist probably "ordinary" wood glue, of semitransparent white color on failed glue joints. The glue joints already failed about 8 years ago within 2 metres above deck level: once the spinnacker boom stove in the forward side, once the main boom the back side. Both damages could be repaired by scarphing in new spruce or reglueing the original wood. No problems since.
Can I trust the rest of the glue joints?
What is the expected life time for a heavily dimensioned mast?
How can I check the condition of the rest?
Is ist possible, that the spray close to deck level was the reason for glue failure there, and the rest further up is trustworthy?
All I know is that up to date the mast works fine, so it would be difficult to take it apart for reglueing. Any ideas and first hand experiences appreciated.
Detlef

[Ian McColgin]

I may be misunderstanding your problem but it sounds as if there were only two problems, both caused by external damage and not glue failure and both have been fixed.

Or maybe you have some new cracks you are worried about.

Or maybe I am confused at the reference to 'white' which sounds like it's observed in the glue near the other two (or more) problem areas but not elsewhere.

It might be that the white is a different glue - someone's prior repair effort - or might be the old glue showing either fatigue or moisture or it might be nothing meaningful.

More information needed.

My general approach to a delaminating mast - which included Goblin's 60 year old hollow masts - has been to first see if the delam can be spread gently and cleaned (fingernail file) and then reglued with epoxy, often applied with a syringe.

Sometimes the crack will spread out from the glue line, and sometimes you have other messes that make this approach fail.

It helps to identify a place a little above the run of the failure and drill a fine hole in the seam at that point. Then split up to the hole and glue up, treating the hole like any screw hole to be filled.

[Bob Cleek]

Ian's right. If you make up some narrow wedges and gently tap them into the crack, you can spread the crack gradually. If the glue is bad, it will come apart very easily as the wedges go in. When the glue seam starts tearing wood away, rather than splitting along the glue line, you know you've got good glue holding. Clean up the open seam and epoxy it. Simple as that. 40 years is plenty to get out of a glued mast before the glue goes... Back then they didn't have epoxy adhesives, which ought to last a lot longer.

[germanreader]

Thanks for the immediate reply. I'll try to give some additional information:
I am worried, because the experts in this forum stated, that the maximum lifespan of a glued mast is about 30 years due to brittlenes of the glue. We want to install an new track this year, and I don't want to invest new fittings, when the basic mast is no longer trustworthy.
I don't know the type of glue the mast was built with, but definitely it is not epoxy, and also not recorcinol (which I would trust). Rather it is sort of standard wood glue. In German we refer to standard wood glue as "white glue", which can be bought in every do it yourself shop, and which is water-soluble before it is cured. Afterwards it is waterproof, but only to a certain degree (e.g. not boil proof). Sorry, but I don't know the chemical composition. In order to illustrate, I described the surfaces of the failed glue joints in the lower portion of the mast.
The damages we had, as well as a little delamination at the top of the mast (under the top fitting), were caused by glue failure. The thrust by boom and spinnacker boom only revealed the problem.
But as I said, the rest of the mast looks fine. I only wonder whether there is such a thing as life expectancy of glue joints.
If I could, I would therefore like to take all glue lines apart, and reglue with epoxy - but they hold together pretty well.
Or is it a case of "never touch a running system"?
Detlef

[Ian McColgin]

I don't know of a reliable way to determine glue life for much of anything since there are so many many many other variables and even when you think you have the answer you often don't.

Age is not a reliable guide. There are too many glue joints that are quite old still in good shape. For example, it's an indoor bit of furniture but my folk have a chair from the 1840's that we know has never been repaired. The mortice and tenion joints that were never glued anyway are a tad loose but the seat, which is just two planks butt glued - no scarf and no under the seat reinforcement - is just fine. I've seen seats of that general construction from the 1960's that have already failed. Go figure.

Similarly, I've know masts even older than Goblin's that were in whole or in part standing up fine and masts not even a decade old failing.

Sometimes a varnished mast fails sooner as the glue (you'd think just the edgoe of a seam couldn't matter and maybe it's a myth but they say . . .) was exposed to more UV than on a painted mast.

But the painted mast fails sooner as you can't spot the failure before it gets big enough to be catastrophic.

Or there might be moisture causing rot at a compression block inside the mast.

Or moisture traveling in through a fastening that happens to be proxomate with a seam.

I think that if you keep a good eye on a mast, fixing what needs fixing and not fixing what's not broken, your odds will be better than average.

[Barteld]

I have a wooden mast of about the same age with about the same problems. It's also heavily dimensioned, and looks quite allright. The delamination at the top is so insignificant I don't worry to much about it. However the delamination at the bottom was a bit more serious. Luckily, it was limited to the part below the mast bolt (is that good english?), so this part doesn't take any or very little stress.

This was caused by water seeping in the hollow mast and accumulating in the bottom. Might that be the problem with your mast? I don't expect a little spray could cause the damage you describe.

A small piece of wood was rotten, luckily, it was the piece that was already scarfed in over twenty years ago. So i simply replaced it again, and expect to get at least 10 more years out of the thing.

The boom also had delamination problems, fixed it with epoxy and an injection needle (Bending it on a rig to open up the seams).

Being in the Netherlands, I expect roughly the same glue was used. I don't worry about it. If it feels firm, and the seams haven't grown much in the last few years, I wouldn't worry to much.

my €0,02

Barteld

[Bob Cleek]

Well, like I said above, if you start driving wedges into the open seam, "leap frogging" one ahead of the other as the seam opens, you will very quickly be able to ascertain the holding power of your glue. If the glue is shot, it will pop open rather easily. If this is the case, disassemble the whole mast, clean the faying surfaces, soak her in penetrating epoxy, epoxy her back together and varnish her up... good as new. BTW, it's also a good opportunity to renew or add wiring inside the spar!

[Mike Field]

That "white glue" sounds to me like polyvinyl acetate (PVA.) I wouldn't use that stuff anywhere on the outside of a boat. And not on too many places inside one either.

If that's the original glue (which it could well be -- forty years ago it was the newest wonder-glue, the epoxy of the 60s,) then you should consider the whole seam suspect. Definitely do your best to open it up as suggested, and keep going even if it means disassembling and regluing the whole spar.

My £0/0/2. ( smile.gif Sorry, couldn't resist.)
.

[skuthorp]

I have recently rebuilt a 16ft, 2 part laminated mast built in 1954. Originally a repair to the sail track, I found that only the hardware was holding it together. Originaly glued with hot amimal glue, it just came apart with slight pressure and the original adhesive was just powder. Fixed it with epoxy, good as gold now. Trouble is the rest of the boat was probably built with the same stuff!

[Buddy Sharpton]

In the back of my mind I keep hearing, "If it ain't broke, don't fix it!" but... A clue might be the previous glue failures. Were they perhaps in response to the thrust of the spinaker pole and boom compression loads overwhelming either too small a glue line or too weak a glue. This might be you head's up the rest of the glue lines are more lightly loaded, thus have survived so far, but are perhaps without much margin of safety. Certainly easier to open up and wonder glue the same size glue lines with the benefit of 40 year's progress in chemistry than to reclaim splinters. How about starting your probe at the spreaders and headstay attachment points, just beyond where there's solid blocking inside. This might be the location of some extra stress, and early distress.

[germanreader]

Many thanks for all comments. Unfortunately, I am less sure what to do than ever. I will do a close inspection later that year, maybe using a fine bladed japanese saw.
If I can't find any gaps at the seams, I will leave the mast as it is. For the next years, no atlantic sailing is intended, just holidays in the mediterrranen.
BTW, there is no solid blocking inside, not even at spreader level. Nor there is solid wood at the base, therefore the mast crushed its side fibres at the base for a couple of years, loosing length about 1/4 inch every year. As the exit of the internal halyards is close to the base, there also is no place for it. After scarphing on new material, we had a stainless base fitting built that forms a kind of "shoe with a sole" which solved the problem.
Thanks
Detlef