westernman
Well-Known Member
Isn't epoxy a bit too brittle to use on the mast?
Wouldn't something a bit more flexible be better?
Wouldn't something a bit more flexible be better?
Stupid, stupid stupid...
- Thread starter NUTMEG
- Start date
NUTMEG
Well-Known Member
Interesting idea. The repair in question is right at the mast base, so no flexing really. Thanks to all for your kind comments and empathetic statements. Can't believe I could have been so stupid. Age?
westernman
Well-Known Member
Is it a keel stepped mast - in which case I think the most flexing occurs just above deck level. But I would be surprised to have rot at the base - unless your bilges have been left full of rain water or rain water is running down the inside of the mast from a fitting which goes through the mast (e.g. VHF cable).
Otherwise with a deck stepped mast I think the most flexing is about 1/3 of the way up from the deck.
Epoxy has the big advantage as a glue of filling in gaps in a strong way (particulary when mixed with microfibres to make a filler). Most other glues do not have this property and require precise joints and a good clamping pressure.
Amulet
Well-Known Member
I'll eat my hat (or at least 1% of it) if you can get it within 1% even with pumps. One of the nice things about the 5:1 and 3:1 ratios is that you can measure "well enough". btw, I thought that Wests were now saying ratio by weight was OK last I read.
macd
Well-Known Member
+1
Can't beat digital kitchen scales, although it's beyond me why some epoxy suppliers insist on giving ratios by volume or by weight but not both.
NUTMEG
Well-Known Member
The mast in question sits in a steel tabernacle. The rotten bit was the bottom 6 pot so inches. Middle son explained that lack of varnish allowed rainwater to seep in, then gravity moved it downwards in the matrix of tiny pipes in the wood. The bottom of the mast had been painted black so the water 'pooled' at the bottom causing the rot. The replaced scarf section is below the pivot point in the tabernacle.
westernman
Well-Known Member
That explains it. And you are right - not much flexing there.
So epoxy would be OK - and is probably a good choice if cannot be sure of getting a perfect joint and being able to apply sufficient clamping pressure.
NUTMEG
Well-Known Member
Michael, just looked at your website, what a simply beautiful boat you have. My dream boat in every respect (apart from berthing costs). My Mk1 Crabber looks similar, from a distance, with one eye closed and in the right light. That's why I bought her when I went out looking for a Colvic Watson! Yours has the 'proper' keel though, lovely!
Amulet
Well-Known Member
The man's right! Fantastic.
lw395
Well-Known Member
No.
Epoxy is not brittle if used properly.
The best and bendiest masts are made out of carbon and epoxy.
OK 'epoxy' is a whole family of gunge, and it depends on how its cured.
I know from experience that araldite can be brittle if cured at 250deg C, but it is also seriously strong....
lw395
Well-Known Member
Best wishes with the project.
As I see it, you have two choices.
Either pull it apart if it will do so without damage, and glue it again.
Or heat it up and hope it bonds well enough. Technically I do not recommend this, but I have known it work. The excess of one component of the epoxy may make a sticky layer on the surface, which will clean off with alcohol.
From what you say, the glue may not be under much load?
If it is too well stuck to pull apart sensibly, I might try baking it.
William_H
Well-Known Member
The fact that the repair area is below the pivot bolt will not make any difference. The Bolt hole should have enough slop in it that when the mast is vertical all load is taken by the base of the mast and none by the bolt. If the joint is a scarfe repair and the load is end on )and it will be huge) then the 2 parts will tend to slip apart one inclined plane against the other. Ideally it should have a step in the joint to take end load or even a vee shaped to notch type joint. Certainly as said remove the bad epoxy and do again with heat.
good luck olewill
good luck olewill
NUTMEG
Well-Known Member
Now thats weird. Before the mast was removed we had a good poke about the tabernacle and without a shadow of doubt there was at least an inch clearance between the mast base and the deck/tabernacle. I know this cos my hand fitted, palm down, under the mast! We also wondered why it had rotted when it clearly was not in contact with the deck.
Could it have been fitted by a moron?
Should it have a 1" hardwood block wedged underneath to take the weight off of the pin?
I did wonder at the pin taking the weight of the mast but assumed maybe, this was how gaffers worked. that lower stresses than Bermudan rigs meant you can get away with this. Now I am really confused!
This is my first gaffer so struggling to understand!
Steve
Could it have been fitted by a moron?
Should it have a 1" hardwood block wedged underneath to take the weight off of the pin?
I did wonder at the pin taking the weight of the mast but assumed maybe, this was how gaffers worked. that lower stresses than Bermudan rigs meant you can get away with this. Now I am really confused!
This is my first gaffer so struggling to understand!
Steve
VicS
Well-Known Member
My kitchen scales are not precise enough for mixing small quanitites. Steps of 2g at the low end ( 5 grams IIRC above 200)
You need to find some that weigh in 0.1 g, or smaller steps, I think for small quantities .
prv
Well-Known Member
Our gaffer certainly didn't work like this. The foot of the mast was curved so that as it slotted into place while being raised, the load came off the pin. You could have removed the pin with it up (though the mast would no longer be safe). The foot had to be well greased with tallow to help it slide into place, otherwise it jammed when nearly home and you got excessive mast rake.
Pete
macd
Well-Known Member
Fair point, although I rarely need to mix quantities that small. Still beats the much vaunted West System calibrated pump, which supplies 8 fl.oz, or half a US pint.