Solar vent bedding/sealant

centerline · May 27, 2014

considering it is not a device that is going to be bedded forever, but only until it needs to be replaced again, I would use the silicone.
remove all the old sealer and clean the area well, fit the new vent to insure it all falls into place ok, then remove it, apply the sealer and screw it down...

there are other bedding sealers that would work also, but properly done in this application, the silicone seal will outlast the lifetime of the vent.

IStream · May 27, 2014

I would stay the hell away from silicone. Butyl tape is ideal for this application. You're in the right place to learn more about it if you need to.

centerline · May 27, 2014

IStream said:
I would stay the hell away from silicone. Butyl tape is ideal for this application. You're in the right place to learn more about it if you need to.

yes I might agree with you, but only if a person doesnt know how to use silicone.

like paint, if the prep work isnt done correctly, it wont last and you will have a bad experience with it, and wont like it any more.

windows have been sealed in boats with it for the past 40-50 years and some of them are still holding fine.... very few other sealers of that era can make that claim.

its not the product, but the person using it that usually is the cause of the failure.... but understandably, it IS still a failure.

and even though I will not tell anyone to stay away from the butyl tape, because it IS good stuff in the right applications, I recently had a very messy failure with it while trying to use it to bed the beckson portlights in my boat.
I ended up cleaning everything up, and prepped them for an install using silicone. and it sealed up the first time and without any issues so far.
if this silicone portlight install lasts for another 37 years in this boat like the last one did, I will highly recommend that the new owner of the boat at that time use silicone again when the portlights need replacing

you MUST clean up the old before applying new.... there is NO WAY around it to insure success.

Stu Jackson · May 27, 2014

centerline said:
and even though I will not tell anyone to stay away from the butyl tape, because it IS good stuff in the right applications, I recently had a very messy failure with it while trying to use it to bed the beckson portlights in my boat.

cl, I'm really, really, really disappointed to hear that. I know you're here a lot, but don't know if you read everything. In many, many discussions about bedding stuff, I have repeated: "...butyl tape is best but the ONLY place on a boat for silicone are for Beckson portlights. It's what Beckson recommends and is the ONLY place on my boat I use silicone anymore."

cl, that alone isn't a reason to recommend silicone to the OP.

To the OP, don't use silicone use butyl tape.

Edit: to cl --- I'd limit your use of silicone on your new boat, too.

IStream · May 27, 2014

I feel about silicone the way many feel about 5200. Except for the specific use case of bedding (some) portlights, I stay away from it. Once you use silicone on something you can never use anything else in that location without resorting to extreme measures (e.g. removing the surface layer of the base material). Even silicone on silicone requires pretty meticulous prep.

John Nantz · May 27, 2014

Was silicone used previously?

If it isn't known what was used on the old vent then there is probability that silicone may have been used.

If silicone was used previously then using it again probably won't result in a leak-free seal. However, if you can sand or file down the surface to get rid of the old sealant then the new stuff, silicone or butyl, should stick, or at least stick better.

Not using silicone is a good idea but the alternatives are limited. Like everybody says, use it once and if there is a leak problem it can be a lot of work to use anything else, silicone included.

For what it's worth, I've used silicone on my Beckson ports and haven't had a problem, but then I've put a LOT of effort into making sure the surfaces are prepped well and that means completely removing all the old material, providing a surface with some tooth, and using the sealant as a gasket instead of as a glue.

Stu Jackson · May 27, 2014

John Nantz said:
For what it's worth, I've used silicone on my Beckson ports and haven't had a problem, but then I've put a LOT of effort into making sure the surfaces are prepped well and that means completely removing all the old material, providing a surface with some tooth, and using the sealant as a gasket instead of as a glue.

John, OP and cl,

I did, too, but I wasn't half as careful as John was, and the 3 (of 8) I have reinstalled are all leak free. Beckson recommends it bears repeating, again, and again...

One doesn't need a glue, as John says, it should be the gasket he mentions, which butyl tape is great for, except on Beckson ports.

But I don't wanna be repetitious...

Chief RA · May 28, 2014

There are definite places to use various sealants. If the craftsman is knowledgable he/she can usually make that decision. We can advise but acting like absolute authorities is not wise. I use silicone more than is advised on this forum. Difficult removal of silicone is the main reason I don't use it even more. If you know the item will have to be replaced, then be cautious using silicone as a sealant for that item.
I just removed a large 15 yr old area of silicone on my boat stern yesterday by using a sharpened putty knife. Light 600 sanding and acetone bared the surface to reapply silicone.

Chief, Ind. Eng.

kito · May 28, 2014

I used butyl tape to bed my solar vents and did a great job of sealing. It will make it easier to replace down the road if needed. I also used butyl tape on the inside flanges of my Grey portlights but used Dow 795 to fill the exterior gap. Butyl tape is not a good choice for filling large gaps imo. I use the stuff MS sells. I would like to know the kind of butyl tape Hunter used on my H30. That stuff is still oosing out from under my toe rail when it's hot.

centerline · May 28, 2014

Stu Jackson said:
cl, I'm really, really, really disappointed to hear that. I know you're here a lot, but don't know if you read everything. In many, many discussions about bedding stuff, I have repeated: "...butyl tape is best but the ONLY place on a boat for silicone are for Beckson portlights. It's what Beckson recommends and is the ONLY place on my boat I use silicone anymore."

cl, that alone isn't a reason to recommend silicone to the OP.

To the OP, don't use silicone use butyl tape.

Edit: to cl --- I'd limit your use of silicone on your new boat, too.

we can please some of the people some of the time, but we cant please all of the people all of the time.... and all I know for sure is what works for me.

I know im young compared to some, but ive had many many fixer upper boats over the past 40 years and I have had to learn how the get the best performance from the products that were available to me (which means extremely affordable because I was born very poor)...

since then I have prospered and discovered newer and better products for certain applications, but silicone is still kept in the tool box. it has never failed me. but there ARE different types of the stuff, and that DOES make a difference, so maybe that is the problem with a lot of silicone failures... the wrong type was used.

but it doesnt really matter how successful i have been with it, your point is well taken. it may not be the better choice for everyone.

and no, Ive not read everything that may have been posted against the use of silicone or other products, and I havent seen and done everything, nor do I know it all yet, but I AM very active and still learning and maybe someday soon i will

, but in the meantime all I can do for people that ask is recommend what ive learned from my personal experiences, and i think im a pretty demanding person when it comes to product performance.

Stu, I mean no offense and take none, but i got a chuckle and had to respond....

Ron20324 · May 28, 2014

I have 8 years on two solar vents in hatches with no problems with silicone. Had to replace one vent, and was easy-out and easy-in.

Stu Jackson · May 28, 2014

Ron, had Maine Sail begun his distribution and promotion of butyl tape that long ago?

IIRC, I bought my two rolls less than five years ago, and while I was not the first, it might have been only a year after he started.

Ron20324 · May 29, 2014

Stu Jackson said:
Ron, had Maine Sail begun his distribution and promotion of butyl tape that long ago?IIRC, I bought my two rolls less than five years ago, and while I was not the first, it might have been only a year after he started.

Tape is not necessarily a magical cure-all, and there is always more than one way to address any problem. As a wise old sage once said, "Your boat, your choice". After a number of replies say it has worked for them, please don't trash the silicone believers just because it's not a product you would choose.

Send me a roll of tape- gratis- and maybe I'd speak well of it, but not badger the nay-sayers.

woodster · May 29, 2014

if what your bedding has mechanical fasteners.... bedding compound is in most cases(99.8%) the sealant to go to...... but if you are setting plexiglass,plastic ports or lexan that depends on a good strong bond...dow 795 is your best choice...it is a silicone based sealant but not 100% silicone in composition like RTV silicone...and bare in mind that 795 is a 30 day cure process to be full strength it is the only silicon i know of that has 50% elongation process this due to the expansion and contraction of the dissimilar materials in the joint make up ie. lexan to fiberglass and gives a very strong bond.....the beading compound is more flexible in the joints and never hardens completely thus always staying resilient and flexible under stress and strain ......they both have there place on a boat the trick is knowing where there place is and proper application

IStream · May 29, 2014

Ron20324 said:
Tape is not necessarily a magical cure-all, and there is always more than one way to address any problem. As a wise old sage once said, "Your boat, your choice". After a number of replies say it has worked for them, please don't trash the silicone believers just because it's not a product you would choose.

I don't think anyone is trashing anyone else. The point of these forums (fora?) is to get information about best practices, watchouts, etc and I think that's what's happening here. I avoid silicone but others love it. That's fine, but people should understand the ramifications of its use. Same thing for 5200, which I use often but others avoid like the plague.