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rustylaru

Composite stanctions and bases

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These keen young folks are doing carbon stanchions

https://www.youtube.com/watch?v=rz9S9miKm9g

Please excuse my ignorance in how to embed a video.

I was wondering if any of you  have an opinion on their method.

G10 backing plate. 6" solid fiberglass stub. G10 deck plate with hole slid over stub. Stanchion post over stub.

 

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The 1st time someone grabs one to pull themselves onboard from the dock it's going to break at the lower hole.

Or worse, at sea.

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its all about how you mount the stub to the hull. He just embedded the solid glass rod in the thick wood deck. I would have used a 12" long solid rod, with bottom 6” half filletted and taped to hull side. I don't think his method is very strong. I guess the top plate transfers the load to the deck in shear well.

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I prefer shiny bits.

I also like known qualities in safety items.

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My boat is cold molded and has a substantial beam at the point the the hull meets the deck. One inch id G10 tubes are let into the deck and into this beam at each sanction. The beam has further reinforcement at this point. The stanchions slide into the G10 tubes. After 20 years no problems. The Stanchions occasionally catch on something and bend but no damage to the tube.

 
A friend's boat was built with 7/8" G10 rods to hold the stanchions. The rods are berried a foot and heavily reinforced, stick up 6" above the deck. The stanchions slide over the rods. After 5 years no problems.

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Why are carbon stanchions out lawed in many racing classes? A stainless stanchion bends, a carbon one explodes. 

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some boats use carbon spreaders as stanchions - more aerodynamic!

anyway, i raced on a boat with G10 rods going through the deck into steel stanchions - they broke regularly.

Gunboats i've been on have carbon stanchions - they break when a sheet or something gets caught and the person on the winch doesn't notice

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11 hours ago, Zonker said:

its all about how you mount the stub to the hull. He just embedded the solid glass rod in the thick wood deck. I would have used a 12" long solid rod, with bottom 6” half filletted and taped to hull side. I don't think his method is very strong. I guess the top plate transfers the load to the deck in shear well.

On my boat pulltruded 1.125" rods were bonded though the deck like that. 1.25" SS stanchion tubes over the top. It does not leak, and we tested it by bending one of the tubes without any damage to the pulltruded pin. It took two big guys leaning on the stanchion for all they were worth to do it. 

If you use G10 rods, be careful of the source: many of them are machined out of G10 plate and aren't that strong. The pulltruded ones are mostly uni directional and both strong and tough. 

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1 hour ago, basketcase said:

Why are carbon stanchions out lawed in many racing classes? A stainless stanchion sucks, a carbon one swallows. 

 

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1 hour ago, Slim said:

 

And titanium ones are anal

 

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So on the subject, what's the verdict on the best stanchion attachment?

I had to remove 2 when fitting my new chainplates and I need to refit in a new location. Might as well do it properly. The old bases and stanchions need replacing anyway so may as well do it now its off. 

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If you have access inside, I'd bond the rods through the deck. Carefully done it will do no harm to your deck finish. You need access inside though to tab them properly. This installation will last as long as the boat, will never require rebedding, and will never leak. 

I'd be wary of carbon stanchions. They do not fail gracefully.

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Kudos to their DIYS enthusiasm, whoever is giving them technical advise might retire or find a new hobby.  Little painful to watch, so much work for??? They could have easily fixed or improved what they had for half the effort and gotten a quality end result, looked like they needed bigger G10 plates on top to spread hardware load. Don't really understand the obsession with synthetic lines and fancy composites if you are not racing.  We have dynex lower shrouds and dynema lifelines, it is invariably the first thing people ask about if they walk by the boat on the dock.  They are usually let down when I tell them the only reason was it was way cheaper for me via the job I had than 1x19 SS and I would not do it again because they grow so much with thermal.  When we got tangled with our friends in a storm one of their SS tube stantions folded almost 90 deg with failing.

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Thank you for your comment everyone.

I was mostly interest in deck attachment and not the carbon post. Metal seems like a good choice for the post.

 I have a foam cored deck. I assume that means even for stainless bases I have to make oversized holes, fill with thickened goo, drill small hole x4 for each base x6 per side.

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Yup. And decent size backing plates of glass or aluminium. About 1/2 the diameter of the fasteners = thickness. If you can get the base either side of a bulkhead, bonus points.

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18 hours ago, MiddayGun said:

So on the subject, what's the verdict on the best stanchion attachment?

Good advice above. If going with traditional metal bases here's two good ideas:

* If there is any evidence of deformation of the exterior deck use a G-10 spacer there. Epoxied to deck. A little larger than the base. Common with lighter-weight cored decks. Can also help with preventing water from pooling there. Looks pro!

* You can really improve the situation if the screw heads are welded solid. That is four leaks prevented. Looks better. Good for shorthanded maintenance. Common with chainplates. Lotsa work though.

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I made and mounted a composite pulpit using old windsurfer mast sections, it came out ok, light, no leaks (yet) but it has a bit more flex than I like. I used g10 plates and glassed them to the bottoms of the tubes. This minimized the size of the penetrations and made mounting easier. It bolts onto an overlapping outside flange for a glass/foam deck, theoretically the flange is solid but I think it has abit of flex.

So I don't know if the flex is in the flange, the g10 connections, or the tubes. If I were to do it again I would make it a bit heavier and stiffer in all three areas. The inboard offset mounting bracketing costs a bit of toe space but I think really improves the stiffness/strength at the fulcrum point. Ntm gives the fairlead option for furler lines etc. That looks like a Shuttleworth? Probably foam around the corner so it won't be the stiffest. You could probably go with a an oversized filled hole/backing plate/local deck reinforcement/wide base bracket style and avoid a major penetration. My 2 cts

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On 1/10/2020 at 6:27 PM, rustylaru said:

These keen young folks are doing carbon stanchions

https://www.youtube.com/watch?v=rz9S9miKm9g

Please excuse my ignorance in how to embed a video.

I was wondering if any of you  have an opinion on their method.

G10 backing plate. 6" solid fiberglass stub. G10 deck plate with hole slid over stub. Stanchion post over stub.

 

Umm, so these diy'er's saved money by doing their own work (twice?)?

Ok, fast fwded thru vid, editing apparently a lost art. Those bases look like they flex too much, given the suspect original construction shown I doubt that bonding directly to the deck is the way to go unless a much bigger base were to be used. Ntm the rod to plate connection is the weak link. Also didn't see a sheer pin.

Edited by Bruno
Completeness

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With old windsurfing masts,  mostly made of fiberglass, most of the flex will be in the tubes themselves 

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I've no interest in composite stanchions, with all the weight in plywood and epoxy I've added recently there would literally be no point. 

I've got the option of either a standard metal base, or a stainless stub that goes right through the deck.
Will probably go with the standard base, quite surprised that I can get away with such a small backing plate Zonker. Kind of assumed it would need to be 10-12mm at least G10 bonded into place. 

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4 hours ago, Zonker said:

With old windsurfing masts,  mostly made of fiberglass, most of the flex will be in the tubes themselves 

Yes, the more wavy more flexy. These were some tubes I got from the mainland with a lot of carbon, unused. They`'re pretty stiff over 1-2', and I added braces or stays to reduce spans, corner loads, etc. When I lean on ot a bit I can see flex at the hull deck flange and at the bases, those are where they the need the extra, m8ght add a low tube at the front which will stiffen a bit.

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A backing plate does 2 things - it acts like a big washer at each fastener and it locally stiffens the deck. It doesn't have to be super thick to do either of these. Use 6mm if your deck is lightly built but for average deck laminates you don't need much - 4mm or so. Some production builders just use fender washers which are a leetle on the light side.

Bonding in place is really good because it reduces the local loads at the fasteners. Few do it.

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8 minutes ago, Bruno said:

Yes, the more wavy more flexy. These were some tubes I got from the mainland with a lot of carbon, unused. They`'re pretty stiff over 1-2', and I added braces or stays to reduce spans, corner loads, etc. When I lean on ot a bit I can see flex at the hull deck flange and at the bases, those are where they the need the extra, m8ght add a low tube at the front which will stiffen a bit.

Or maybe some glassed in small triangular brackets at the tube connection/deck connection?

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22 hours ago, Zonker said:

Yup. And decent size backing plates of glass or aluminium. About 1/2 the diameter of the fasteners = thickness. If you can get the base either side of a bulkhead, bonus points.

So you mean to plan my layout so as to miss bulkheads?

I have a bunch of G10 1/4" for backing plates.

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11 hours ago, Bruno said:

That looks like a Shuttleworth? Probably foam around the corner so it won't be the stiffest. You could probably go with a an oversized filled hole/backing plate/local deck reinforcement/wide base bracket style and avoid a major penetration. My 2 cts

Thanks for your 2 cts.

What local deck reinforcement. Could that be another piece of G10 on top of deck a little larger that the stainless base as someone suggested above? 

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6 hours ago, Zonker said:

Or maybe some glassed in small triangular brackets at the tube connection/deck connection?

Right, that'swhat I meant by inboard offset.

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3 hours ago, rustylaru said:

So you mean to plan my layout so as to miss bulkheads?

Just that if place a stanchion base immediately adjacent to a bulkhead (NOT on top of it), the deck will be nicely stiffened up locally. Less stress on the deck, stronger connection etc.

But only if it makes sense of course. Nothing says you have to use exact same spacing between them.

1/4" G10 will be fine.

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