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Irrationally Exuberant
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I've been surprised and pissed to find that Beneteau used silicone to bed pretty much everything on my 13 year old boat. First I found silicone under the winches and just figured they were the work of a lousy dealer equipment install. Same with the windlass. But now that I've run into the dreaded stuff bedding a dorade vent and water deck plates, it looks like this was the company's practice. Have other's noticed this? I didn't think any boat builders used silicone. BTW, my particular boat was made in France.
 

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Some even bed their portlights with it. One can make a case that silicone is inexpensive, stays flexible, and is easily replaced when need be, without the need to use a crowbar to unmounts the equipment (like 5200 might require.)

I'm not saying it is the "best" material, just that it isn't totally crazy.
 

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It's cheap and easy. No surprise, just disappointing.

At least I found beveled deck holes under my stanchions as I've been replacing the silicon with buytl.
 

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Irrationally Exuberant
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Discussion Starter #5
Ah, so you've got silicone on your Jeanneau, then Minne?

One good thing on the Bene is that the stanchions and some of the hardware, such as the winches, were installed over solid fiberglas, so a leak wouldn't cause a core problem. And I have to say, I've seen no evidence of leaks anyway. Which I figure makes this a good time to look at the stuff that is through core--before I see some depressing core moisture.

Good point HelloSailor, though there are plenty of choices in between silicone and 5200!
 

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Discussion Starter #7
Thanks for the jolly wishes, xymotic! :) I've heard of that problem. What kind of boat do you have? Personal experience with that?
 

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The only place i think that i have found it is in my stanchion bases. But; i haven't verified that's what it is. No leaks so far so i really don't take things apart. I do plan on rebedding my winches soon just to make sure. Maybe there is some there? Replaced most of the thru hulls all ready ;)

'93 Oceanis 400
 

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Ah, so you've got silicone on your Jeanneau, then Minne?
I did. Most of the stanchion bases have been redone in buytl now.

some of the hardware, such as the winches, were installed over solid fiberglas, so a leak wouldn't cause a core problem.....
Same here, however, water would constantly find its way to the bilge whenever it came over the rail, it rained or we washed the boat. Wasn't a big deal, until a leak found its way down the electrical patch panel. :eek:
 

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Certainly the winches on a Beneteau or in any other boat are not put in place only with silicone. Silicone is there, as in all other places that have other kind of fixation to warranty the water is not coming in.
There will of course be fastenings but silicone is the worst possible sealant. It isn't as permanent as was originally thought and leaves a residue that other sealants will not stick to - even new silicone. It is very hard to remove, sanding often being the only way.

5200 is a lousy choice as well, for the reason that it adheres too well, often pulling up gelcoat when the item is removed.
 

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Silicone is a pretty good bedding material. The down side is it's hard to get off when prepping to paint. The boat won't need painting for 30 years, so what's the big deal?
 

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I would argue no worse than some of the others. I wouldn't use it except for plastic parts, but I can see why the builders would use it.
 

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I would argue no worse than some of the others.

The point is you (we, anyone) can argue - because it is not the best choice for bedding of deck hardware. It's cheap, it's easy, it does not have a stellar life span (5-7 years) and it's very hard to get cleaned up and removed if you want to change from it.

Folks that buy boats in the modern era EXPECT them to be built using modern materials especially when they come with modern prices.
 

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There will of course be fastenings but silicone is the worst possible sealant. It isn't as permanent as was originally thought and leaves a residue that other sealants will not stick to - even new silicone. It is very hard to remove, sanding often being the only way.

5200 is a lousy choice as well, for the reason that it adheres too well, often pulling up gelcoat when the item is removed.
mitempo, I am talking about silicone as a generic name for a vast range of products, the ones that are soft and serve as sealant. Some have no silicone at all.

I believe that when the OP talked about silicone he used the term in a generic way.

Regards

Paulo
 

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mitempo, I am talking about silicone as a generic name for a vast range of products, the ones that are soft and serve as sealant. Some have no silicone at all.
Paulo: You might be the only person I've heard of who would use the term "silicone" to describe all soft sealants. No one would consider Polysulfide (Lifecalk) as a silicone.

Silicone (and silicon-family products like Lifeseal) do have an application for bedding plastic. That doesn't apply to stanchions or winches though, and butyl seems like a better choice.
 

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What's bad about silicone? Please educate me.
Biggest issue with silicone is that it has "oils" that leach out of it and are extremely hard to clean off. This residue makes it very difficult to get anything else to seal. This residue is very chemically inert, and does not clean up even with harsh solvents. So you are left with a surface that will not take any other sealant, not even new silicone. You wind up having to sand it off in most cases.

The other issue is that it does not have a very long lasting bond, and often starts leaking in as few as 4 or 5 years. So if you still own the boat, you are in for some serious work to get a good seal when you have to re do it. They market it like it lasts for ever, even offering a lifetime warranty on some home stuff. I have never figured that out.

There are some exceptions and that would include Dow (don't remember the number now) that is actually a structural adhesive as well as sealant. This is the best choice for Acrylic ports. But otherwise there is not much place for silicone.

I can see why it is used on a production line, first of all you are really only looking for it to last longer than the warranty, this will likely be the case. It is very quick to use coming out of a bulk fed gun. Much faster than cutting butyl, though not a lot of difference when DIY as you are likely only doing one or two stanchions at a time. Poly sulfide is a good alternative as well because it cleans up fairly easily but does not seem to have the elastic properties that butyl has.
 

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Irrationally Exuberant
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Discussion Starter #20
mitempo, I am talking about silicone as a generic name for a vast range of products, the ones that are soft and serve as sealant. Some have no silicone at all.

I believe that when the OP talked about silicone he used the term in a generic way.
Paulo, as Alex suspected, I definitely was not using "silicone" in any kind of generic way to mean "bedding goop." Polyurethanes, polysulfides, butyl are fine, silicone not. Silicone has those nasty features that others have pointed out, the worst being that while it doesn't last forever as a sealant, its residue does last forever and resists subsequent sealing.
 
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