johnalison
Well-Known Member
Another Specsavers failure I'm afraid
How to mount stanchions?
- Thread starter coopec
- Start date
lustyd
Well-Known Member
Hopefully never, but I assumed based on the original post that there was a hope these would do more than hold fenders up and dry towels. The extra length of these stanchions gives them extra leverage so all being equal they are more likely to rip out of the deck if they become the last line of defence. I know I could rip three bolts through with a 1m crowbar, so ply and plastic are not sufficient if strength is required.
Keith-i
Well-Known Member
I’ve just recently refitted the stanchions on my balsa cored deck after some intensive repairs. I placed a grp pad rather than ply at each high load attachment point. For sealant I used butyl tape. It compresses somewhat and oozes out but maintains a waterproof seal. I also countersunk the holes to give a bit of space for the butyl.
coopec
N/A
I have just spoken to the fiberglass expert at Kirkside Products regarding backing plates for the stanchions and he says to use glass cloth (which I already have) and do a lay-up using polyester or epoxy.
He says he would use polyester resin as it would be stiffer than a lay-up using epoxy. He says two layers should be quite stiff but if I need it stiffer to do an extra layer. I think that's the way to go.
He says he would use polyester resin as it would be stiffer than a lay-up using epoxy. He says two layers should be quite stiff but if I need it stiffer to do an extra layer. I think that's the way to go.
geem
Well-Known Member
On my boat, every day. I lift the dinghy each night. We bring it alongside. I fasten the dinghy lifting bridle to the spinnaker halyard ready to lift. I climb up the side of the boat using the lifelines. They get my 75kg pulling on them. The solid aluminium stanchions flex. You can see it. Nothing moves as they are bolted to a substantial aluminium toerail.
geem
Well-Known Member
I think that is exactly how I would do it. We have a couple of fittings on our deck that have leaked and rotted the ply set in the core. I suspect they had been leaking for years.
We removed the ply and filled with solid glass.
Daydream believer
Well-Known Member
He would do though, wouldn't he, because he would be biased, being a fibre glass expert.I have just spoken to the fiberglass expert at Kirkside Products regarding backing plates for the stanchions and he says to use glass cloth (which I already have) and do a lay-up using polyester or epoxy.
He says he would use polyester resin as it would be stiffer than a lay-up using epoxy. He says two layers should be quite stiff but if I need it stiffer to do an extra layer. I think that's the way to go.
If you asked an aluminium expert, I expect that he would suggest aluminium plates- because that would be his expertise.
I do not mean the above to be disrespectful to them, but to point out how they might be most likely to think.
Try asking someone with a wide ranging set of skills & you may get a more balanced reply.
Sticking fibreglass over one's head in a confined space under the side decks will be hassle & you will , possibly, drip resin so have to be careful about protection. Head (hair) protection will be a must. I would expect that you would still have to distribute the load around the nuts with some large washers or plates.
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Daydream believer
Well-Known Member
I am very careful about such things. When coming alongside I often get helped by outsiders (which I usually appreciate) but I do ask them not to push on the guard rail if I see them pushing it ( unless it is a case of a panic due to my mess up). I do explain that it is to avoid flexing the stanchions, so they know why. When climbing aboard I do so using the shroud for leverage. Being tall I find it much safer as well.
My stanchions are fixed to the aluminium toe rail as well as the deck, but I see no point in tempting fate.
geem
Well-Known Member
I bought my boat to use it.
D
Deleted member 36384
Guest
It has been reported on YBW that backing plates less than 3mm or penny washers will bend and appear cupped, as the thinness is not stiff enough to resist yielding. Apparently for stainless backing pads, 3mm is the minimum thickness required to distribute the load. I think it was Thinwater that posted this a while ago, maybe based on Practical Sailor tests.
coopec
N/A
NO! NO!
I know the guy at Kirkside very well and he would be quite genuine. How much money is he going to make out of this job?
This afternoon I found a sheet of heavy plastic 6ft X 18in. X ¼in. and laid it on a flat surface. Then I cut 6 strips of woven glass cloth 4ft X 1ft. Tomorrow I will use polyester resin to to laminate them on top of my large sheet of plastic. Once I get them to the desired thickness/stiffness I will cut them to size and drill them. (I think x3 laminates will be fine)
I will use butyl and I like Keith's idea of countersinking the holes. But I'll use "O" rings as a previous commenter has suggested.
D
Deleted member 36384
Guest
The picture of your stanchions, are they solid bar, or tubes with a cap welded on?
coopec
N/A
"3mm is the minimum thickness required to distribute the load."
If the strip is narrow (3in.) It may bend but if the strip is 6in. wide it would be a lot harder to bend.
If I think there is a possibility it may bend I'll laminate another layer. (I don't think it would be necessary- we'll see)
coopec
N/A
D
Deleted member 36384
Guest
It’s a shear load, if too thin it will yield, which was the point. It’s not about width.
Graham_Wright
Well-Known Member
For what it is worth, my stanchions at a similar length (one metre) sit in 100mm long SS sockets which have a through-deck stem threaded M20. The underside is backed up with a stainless steel plate and the socket has a 100mm diameter base.
I think that is super strong!
I think that is super strong!
coopec
N/A
What is your yacht constructed of? Steel?
geem
Well-Known Member
I would suggest 6mm minimum for glass backing pads. I have made sheet epoxy/glass for jobs on my boat. It will take about 6 to 10 layers of heavy glass to get to 6mmNO! NO!
I know the guy at Kirkside very well and he would be quite genuine. How much money is he going to make out of this job?
This afternoon I found a sheet of heavy plastic 6ft X 18in. X ¼in. and laid it on a flat surface. Then I cut 6 strips of woven glass cloth 4ft X 1ft. Tomorrow I will use polyester resin to to laminate them on top of my large sheet of plastic. Once I get them to the desired thickness/stiffness I will cut them to size and drill them. (I think x3 laminates will be fine)
I will use butyl and I like Keith's idea of countersinking the holes. But I'll use "O" rings as a previous commenter has suggested.
coopec
N/A
Geem
How do you know what weight glass cloth I am using?
. I don't think I need anything like 6mm (¼ in.)I'll start laying up and continue until I think the strength is adequate.
I could of course lay it up in a "U" shape which would give it extra strength.
PS (Addition) Maybe I should be using Chopped Strand Matt (CSM) and Woven Roving (WR).
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Daydream believer
Well-Known Member
Clearly you have already decided on what path to take - that is your perogative- so further comment is only creating unnecessary animosity.NO! NO!
I know the guy at Kirkside very well and he would be quite genuine. How much money is he going to make out of this job?
This afternoon I found a sheet of heavy plastic 6ft X 18in. X ¼in. and laid it on a flat surface. Then I cut 6 strips of woven glass cloth 4ft X 1ft. Tomorrow I will use polyester resin to to laminate them on top of my large sheet of plastic. Once I get them to the desired thickness/stiffness I will cut them to size and drill them. (I think x3 laminates will be fine)
I will use butyl and I like Keith's idea of countersinking the holes. But I'll use "O" rings as a previous commenter has suggested.
I would make the point, however, that the question of money never crossed my mind. It was certainly not meant to create a dispute, Only point something out that may have been missed.