Mfgr Says Use Only Silicone! WTH...Everyone Here Says Don't Use Silicone.

[boatsail]

I'm ordering portholes from defender and the mfgr says to use silicone. Every time I read something on cf, I hear that you should NEVER use the stuff on a boat. I'm confused. What are your thoughts. Is there something you would use instead?
Here is the porthole
Beckson Newport 4 X 14 Opening Port / Self Drain

"Note: Only silicone caulk is recommended"

Most Beckson Ports come with Standard 1" or 2" Spigot Lengths. Beckson 3 x 10 / 310 Models have a 1-1/4" Spigot. The spigot is the integral part of the port's frame, which passes through the cabin wall. Spigots should be trimmed flush after installation for best drainage. Note: Only silicone caulk is recommended

[model 10]

Why would you ignore Beckson and trust this forum?

[boatsail]

Originally Posted by Guy

Why would you ignore Beckson and trust this forum?

That was my thought, but to be honest, I see a reason for no silicone and there are knowledgeable people even boat builders on here who have opinions and reasons behind the opinions and alternatives. Was really wondering if there was a sound solid set of logic behind an alt to silicone and what that alternative was and application. If I did not get something that sounded logical, then no doubt I would use silicone and go with it. Sometimes there is something better than mfgr.

Just kind of made me think as I hear the no silicone thing on here all the time. Figured I would ask knowlege from someone other than me, because if I had no other information, silicone all the way, no questions asked.

[kthoennes]

It's because once you use silicone the first time, it's very difficult to get anything to adhere well to that surface ever again. If your portholes are perfectly installed and will last the lifetime of the boat, and will never have to be re-bedded go ahead.

[boatsail]

Originally Posted by kthoennes

It's because once you use silicone the first time, it's very difficult to get anything to adhere well to that surface ever again. If your portholes are perfectly installed and will last the lifetime of the boat, and will never have to be re-bedded go ahead.

That was my understanding. That being said, what is the alternative that I should use for bedding my windows?

[goboatingnow]

Originally Posted by boatsail

That was my understanding. That being said, what is the alternative that I should use for bedding my windows?

Why not drop them an email and ask why they only suggest using silicone

Dave

[MarkJ]

I have never heard a No Silicon thing on here.

Do you mean no 5200? The adhesive silicon used to bond decks to hulls? People often put that on places they shouldn't, like portholes etc. one shouldn't use 5200 on portholes because if you ever need to change it you have to dynamite the boat.

[boatsail]

See. the no silicone

http://www.cruisersforum.com/forums/...ail-95982.html
reply #2
" Silicon should never be used on boats."

http://www.cruisersforum.com/forums/...0-a-98876.html
reply 6
reply 7
number 10 "I have a rule - no silicone on the boat."
number 14 says
"BUTYL tape is what you need. 4200 is an adhesive, NOT a sealant, don't use it. Silicone should only be used on Beckson portlights because that's what the manufacturer recommends. Silicone is not a great sealant.

Try this, great source for butyl tape:

Bedding Deck Hardware With Bed-It Butyl Tape - SailboatOwners.com
__________________"



I have been researching everything that I can find. Only the mfgr recommends it. others seem to recommend other things from polyurethane caulks to butyl.

I have been putting a lot of time and money into the boat and just want to make sure I do the right thing. I don't want to have issues in the future from a job I could have done better.

[boatsail]

Typically, I go with mfgr rec. I will be taking the advice and emailing or calling them tomorrow. I have just heard not to use it enough times and the logic behind not using it seems, well, logical. This is the internet, sometimes we have to much information!

[kentobin]

Paint won't stick to silicone and from what I've read anything that every had any silicone on it. Everyone has a favorite and I like butyl tape but you have to find a good supplier. I bought some on Amazon and it wasn't very good quality. I'd recommend looking at Need Butyl Tape ?? Photo Gallery by Compass Marine at pbase.com which has some very good photos but it's not what I'd call cheap.

[kthoennes]

I used a polysulfide adhesive marine sealant called Life-calk to seat the new bow hatch. Not silicone, and according to the specs it's a composite so it doesn't attack plastic like old polysulfides. It's also not polyurethane based so it doesn't take a Star Wars laser beam to remove it later - I cleaned off some stray set globs with a sharp hard plastic scraper.

[Paul Elliott]

Originally Posted by MarkJ

Do you mean no 5200? The adhesive silicon used to bond decks to hulls?

Mark, 5200 is a polyurethane adhesive -- it is not silicone-based.

I've been told by people who do gelcoat repairs for a living, that once someone has used silicone sealer (or any silicone product) the only way to patch that area is to grind out the contaminated surface. Gelcoat, epoxy, or polyester resin won't adhere to it otherwise.

For what it's worth, 3M also has "4200" which is also a polyurethane adhesive / sealant that is easier to remove than 5200. I've used it and it seems pretty good.

[captainjay]

DAP Dyna flex 230, as a former contractor I have used hundreds of tubes of this stuff. I used it to re-bed a large round hatch on my boat a couple of years ago. Plastic framed two foot round hatch. It worked great and hasn't leaked a drop. I know it doesn't say marine on the tube which means it sells for less than $10 a tube. I wouldn't use it below the waterline, but I would have no problem using it on cleats, deck plates, hatches port lights etc.
http://www.dap.com/docs/tech/00010001001.pdf

Jay

[Blue Stocking]

Next time you walk past a tall commercial building that's all glass, look at the joints. If its the type where there are no metal strips covering the joints, the glass will be held in with butyl tape and the seams filled with silicon up to 5/8" wide by 1 5/16" deep.
That ought to tell you something about the tenacity of these compounds.
Here in Bermuda, we often design for about 155 mph.

[Adodero]

The PO of my boat used silicon to bed a lot of hardware. It held up OK in most areas as the coring is dry in a lot of places where he rebedded the hardware (e.g. cleats on cabintop, etc). I've since rebedded most of it and there were no signs of water intrusion around -MOST- fittings...

That said, the areas that had large amounts of water on a frequently basis showed signs of core rot. Fortunately for me, the area is very small and will be easy to repair, but it is still there. The leaky fitting was on the floor of the cockpit, where water tends to build in significant amounts. I've noticed similar "performance" from silicon with fittings along the water drainage path on deck, they also leak. Note this bedding was in place less than 2 years.

The worst part about silicon is what you are doing to the next owner. Whoever wants to rebed the hardware next will have to sand and drill to use anything but silicon.

TL;DR: If the fitting is exposed to water on a regular basis (particularly if it's standing for any amount of time), don't expect silicon to hold up. It's a pain to remove once you have used it.

IMO there is no reason not to use butyl tape. It's easier, cleaner, and more effective.