How do you fill small screw holes in fiberglass?

[Leah]

I want to fill some small to medium size screw holes What's the best method? I want it to look as pretty as possible thanks Chuck

[Tim]

Depending on the location of the hole, often the best method is to just install a screw or bolt. Gelcoat repairs are an exercize in frustration and bad looks, and usually look worse than the raw hole, leaving you wondering why you bothered.

Use a panhead or ovalhead screw or bolt to provide a finished look. Use a washer only if absolutely necessary, and install the screw or bolt in plentiful sealant. This usually looks better than any other kind of repair, and sure is a cinch.

[rshowarth]

Hi Tim-

What kind of sealant would you recommend?

[Tim]

I generally choose polysulfide--something like 3M 101.

NEVER use silicone. Never, ever, ever, ever. This is a quiz, now class: what is the forum mantra for silicone?

First person to answer correctly gets a kewpie doll!

[dasein668]

Silicone is the work of satan.

[rshowarth]

Tim and Nathan-

I've got it. 3M 101-Yes

Silicone-Never, ever, ever, ever...

[Matt B.]

Tim and Nathan-

I've got it. 3M 101-Yes

Silicone-Never, ever, ever, ever...

Seconded. A PO used silicone to seal all of the hardware on the WyldSide... I don't know who they were, and right now they should be glad of that.

I'm particularly "amused" by the inch-thick ring of silicone inside the sidelights.

[dkall]

Silicone has a place in the boat. Where you want a water tight seal but don't want a glue. Where you're putting glass in a metal port. Where you're putting rubber to plexi. On the mast between dis-similar metals with a polycarbonate divider.

I don't believe in silicone on any parts that have any stress.

One old philosopher said; "Never say never".

I'm sure I'll get slamed some for the above and if anyone wants specifics I'll be glad to provide them. So bring it on. :)

[dasein668]

That's great... I just hope you never have to remove it. I would (and have) choose butyl for the applications you suggested.

[bcooke]

I'm sure I'll get slamed some for the above and if anyone wants specifics I'll be glad to provide them. So bring it on. :)

And they say I am the crazy one. I would rather post nude photos of myself than try and support the use of silicone on this forum :-)

-Britton

[dasein668]

And they say I am the crazy one. I would rather post nude photos of myself than try and support the use of silicone on this forum :-)

And I would definitely prefer if you didn't! hehe

[Tim]

I would rather post nude photos of myself...

Does that have to be the only other option?

[Tim]

Silicone has a place in the boat. Where you want a water tight seal but don't want a glue. Where you're putting glass in a metal port. Where you're putting rubber to plexi. On the mast between dis-similar metals with a polycarbonate divider.

I don't believe in silicone on any parts that have any stress.

One old philosopher said; "Never say never".

I'm sure I'll get slamed some for the above and if anyone wants specifics I'll be glad to provide them. So bring it on. :)

No, we don't slam people here.

The thing with silicone is that it tends to adhere so tenaciously in a thin film, and therefore is next to impossible to remove completely. It manages to resist scraping, solvents, and sanding; and, of course, all of these activities, if employed, will tend to spread the contamination around to a wider area. This can lead to difficulties with future adhesion of new sealant, paint, fiberglass, or just about anything else.

I advise against silicone as a matter of course because of these difficulties, and because I feel that there is always another choice of product that will work as effectively, or more so, than silicone in any application on board, but without the potential difficulties involved with silicone.

There is no single sealant product that is perfect for every job on board; a selection of several is required, at a minimum. But I feel that silicone, given its limitations and the problems described above, doesn't need to have a place in this arsenal, and that it's better to choose something else that will avoid the pitfalls.

[tikvah59]

I feel that there is always another choice of product that will work as effectively, or more so, than silicone in any application on board, but without the potential difficulties involved with silicone.

Tim,

I thought silicone was the recommended choice when sealing acrylic or especially lexan ports. Do you use butyl on on your large fixed ports, or something else?

[dasein668]

I used butyl to seal my ports. 2.79 a tube at Ace Hardware, white. Messy to install (right Britton?) but cleaned up well. If I had made that kind of mess with silicone I'd probably have walked away from the boat and never returned.

After one season the butyl has been great. I have one deadlight which needs to be reinstalled, but it leaked from day-one due to incorrect installation. Silicone wouldn't have fixed that...

Hey Britton, what are you doing in early May? hehe

[Jason K]

I used butyl to seal my ports. 2.79 a tube at Ace Hardware, white. Messy to install (right Britton?) but cleaned up well. If I had made that kind of mess with silicone I'd probably have walked away from the boat and never returned.

I used butyl as well on all of my ports. It was an incredible mess, but it cleaned up easily enough. The only leak I have is in one the large deadlights, but that's because the screw isn't long enough to grab the threads on the outer frame. I keep meaning to fix that...

As Nathan says, if I'd have had that much silicone excess, it would have been an absolute nightmare. I had my share of removing silicone when I pulled all the hardware off last year. That was quite enough, thank you very much.

The problem (OK, well one of them) is that even after you've cleaned up 99% of the goop, it leaves behind a that thin film residue that is a bear to get up - even with powerful solvents, paint scrapers, and colorful language. You can't paint over it, you can't sand it off and, if you leave it, it'll just spread over the whole boat.

It seems to me that this is a no-brainer. I just can't see any advantage to silicone, particularly for portlights. When compared to butyl, silicone is (1) more expensive, (2) less effective, and (3) near impossible to properly clean up. Why use it?

[Tim]

I feel that there is always another choice of product that will work as effectively, or more so, than silicone in any application on board, but without the potential difficulties involved with silicone.

Tim,

I thought silicone was the recommended choice when sealing acrylic or especially lexan ports. Do you use butyl on on your large fixed ports, or something else?

You can't use polysulfides on these plastics, as there is a chance of a reaction with the plasticizers in the lexan or acrylic. This has led many people to choose silicone, as of the "big three" marine-type caulks, this would be the only suitable one. But butyl is a better choice here. Either the hardware store variety, or, if you can get it, the good stuff used by glass shops. Butyl is good because it remains nice and pliable, and can be removed later without the problems associated with silicone.

By way of full disclosure (and it's on my website on the appropriate project page as well), I admit that, 6 years ago and for reasons that I still don't understand, I sealed my ports with silicone. We all have room to learn. I regret using the silicone, though none of the ports leak. I will never use it again, and I dread the day when I need to remove and rebed my ports for whatever reason.

It was at the end of my first season post-restoration that I formed my now strong opinions anti-silicone. The project was coaming removal; I had used small dabs of silicone at the screw locations, and removal was a nightmare. The silicone spots are still in place on the backs of the coamings and on the fiberglass bearing surfaces.

[Tim]

I feel that there is always another choice of product that will work as effectively, or more so, than silicone in any application on board, but without the potential difficulties involved with silicone.

Tim,

I thought silicone was the recommended choice when sealing acrylic or especially lexan ports. Do you use butyl on on your large fixed ports, or something else?

You can't use polysulfides on these plastics, as there is a chance of a reaction with the plasticizers in the lexan or acrylic. This has led many people to choose silicone, as of the "big three" marine-type caulks, this would be the only suitable one. But butyl is a better choice here. Either the hardware store variety, or, if you can get it, the good stuff used by glass shops. Butyl is good because it remains nice and pliable, and can be removed later without the problems associated with silicone.

By way of full disclosure (and it's on my website on the appropriate project page as well), I admit that, 6 years ago and for reasons that I still don't understand, I sealed my ports with silicone. We all have room to learn. I regret using the silicone, though none of the ports leak. I will never use it again, and I dread the day when I need to remove and rebed my ports for whatever reason.

It was at the end of my first season post-restoration that I formed my now strong opinions anti-silicone. The project was coaming removal; I had used small dabs of silicone at the screw locations, and removal was a nightmare. The silicone spots are still in place on the backs of the coamings and on the fiberglass bearing surfaces.

[Matt B.]

The thing with silicone is that it tends to adhere so tenaciously in a thin film, and therefore is next to impossible to remove completely. It manages to resist scraping, solvents, and sanding; and, of course, all of these activities, if employed, will tend to spread the contamination around to a wider area. This can lead to difficulties with future adhesion of new sealant, paint, fiberglass, or just about anything else.

So, for those poor suckers like me who are cleaning up the silicone left by a previous owner (flippin' navy, think they'd know better!) - what's a body to do? I think cutting out and patching the areas of fiberglass seems a little extreme, but the stuff is under most of the hardware I just got done pulling off, and not all of it's going back on.

[Tim]

All you can do is try! Scraping is your best bet, as it is least likely to spread the stuff around. Sanding is the worst, as it tends to press the silicone into surrounding areas.

Good luck with it. It's a miserable chore.

[bcooke]

bcooke wrote:
And they say I am the crazy one. I would rather post nude photos of myself than try and support the use of silicone on this forum :-)


And I would definitely prefer if you didn't! hehe

Does that have to be the only other option?

What's the matter guys? Don't you think I'm Sexy?

flippin' navy, think they'd know better!

They did. They sold the boat to you rather than deal with the problem :-)

It is not just the Navy though. Silicone is everywhere. Tritons are held together with the stuff. I developed my own aversion to silicone when working as a mechanic. It seemed to hold well and then inexplicably let go all at once.

The big issues in the boat world seem to be from silicone contamination with the painting and glassing process. I suppose if you had good gelcoat or otherwise weren't going to paint and the structure was sound and no glassing was ever going to happen in the vicinity then silicone could be used with success. Most of the posters on this board however will be painting and glassing which may explain the strong negative reaction to silicone. I don't like the stuff personally but I can see how some people decide to use it.

Hey Britton, what are you doing in early May? hehe

I ask again. Do you not think I am sexy?
Since I will be boatless this next summer perhaps we can work out a deal :-)

-Britton

[kendall]

I don't like silicone in any form, and try to stay away from it as much as I can, not always possible because there are some apps where it's just the most functional.

I have found that when removing it what works the best is to either keep it wet with good soapy water while sanding, or keep a steady water flow going, to flush it away as soon as it's freed up and keep it from redepositing, but if it's draining somewhere that it's going to pool up you just move the problem.

scotchbrite type pads work great for scrubbing it off.

Ken.

[Tim]

scotchbrite type pads work great for scrubbing it off.

As long as you're not concerned about the condition of the underlying surface! If you have a surface in good condition and are trying to remove silicone in this way, you could easily scratch or damage the finish. For use during part of a rebuild project, scrapers and Scotchbrite are the way to go. Of course, the Scotchbrite pads also run the risk of transfering the contamination to surrounding areas, just like sandpaper.

[dkall]

In addition; I remember; although my brain is begining to fog sometimes; that you there is a silicone removal product and there is a product you can put into paints like awlgrip that will help keep any orangepeeling from silicone. It isn't the best solution but it may help.

[Robert The Gray]

This is conjecture based on imagination rather than any direct experience. I wonder if one way to use silicone safely on a boat is to let it cure fully before application. With the appropriate use of a mold, one could create custom gaskets that when fully cured might leave no residue on the mating surfaces. When cured I think silicone is quite stable. Is the key to not let any uncured silicone come in contact with the boat?

On my WC triton main salon ports I switched from ten 1/4" bolts per large 3/8" polycarb port light to 19 3/16" bolts per 1/2" acrylic port light. I have also bedded them in silicone. o joy and rapture. Who knows what awaits me in the future. Needless to say I dislike this method and feel it is crude and lacking in refinement. The bronze frames of the east coast style are beautiful and add a touch of history and permanence. I feel some times like I am at the helm of a 1960 Impala. A clean one, tricked out and classy but still a Chevy Impala.
Any waaay I was thinking that if I was to do it right I could fabricate custom gaskets, four from the same mold, out of silicone for use in these port lights. I can clean then every year.....yea, I could.....

hmmmmmm.....

One obvious advantage to choosing this course of action is that I would once again gain questionable mastery of some obscure fabrication method at great expence to both my self esteem and finacial liquidity. I am thinking the situation calls for caution. Guide me great masters!! Is this course the way of madness and chaos? Am I beam reaching on the false breeze of cranial flatuence? Am I being drawn exorably into that eddie of boat nerdery where one is trapped and left spinning, lost and adrift, independent of the wind and tide? Can well cured silicone be used on a boat?

humble in the face of boat mystery

R

[Jason K]

Can well cured silicone be used on a boat?

Interesting thought, but I'd say nope. It needs to cure in place to provide a water tight seal. It's used because it is both adhesive and works as a gasket that can expand and compress. Without the adhesion, you'll never get a water tight seal and all you would have would be a sub-par gasket.

Just go with butyl when you rebed those portlights.

Good luck cleaning the old silicone up. It sucks, but is certainly doable; I did it with a lot of acetone first and then with the Interlux solvent wash, which worked much better than regular acetone. I got as much up as I could with a scraper and worked on the residue with the Interlux and a lot of those thin scotch-bright pads (the ones that are only the rough part). I kept a bag handy to toss the used ones in in order to keep contamination to a minimum.

[rshowarth]

I was going to remove and refasten my portlights because they did not look presentable. I am having an extremely difficult time trying to remove them. So much so, I will probably seal them back up, and if they do not leak, leave them alone.

I suspect silicone.

I have removed a seat locker cover and it's frame, scraped the old sealant and am planning on rebedding it.

Should I use polysulfide or butyl?

Also, please recommend a brand and name for the butyl.

Thanks,

[Jason K]

I have removed a seat locker cover and it's frame, scraped the old sealant and am planning on rebedding it.

Should I use polysulfide or butyl?

Polysulfide. I only use butyl for portlights and polysulfide for bedding hardware, etc. It's a little bit easier, a little bit cleaner, and I have a hard time finding white butyl.

Also, please recommend a brand and name for the butyl.

You can find it at any Lowe's/Ace/ Home Depot type store. A lot of times it's labeled for gutters and flashing. Read the somewhat fine print to be sure it's butyl.

I was going to remove and refasten my portlights because they did not look presentable. I am having an extremely difficult time trying to remove them. So much so, I will probably seal them back up, and if they do not leak, leave them alone.

They will probably leak if you've put any effort at all into their removal. Why are you having such a hard time? The Mariner (that's the boat we're talking about, right?) has, if I'm not mistaken, just one large portlight on either side of the main cabin. How are they attached?

You'll likely need a large screwdriver or other long tool that will make a good lever and a smaller one that you can use as a wedge. Wedge a small opening between the frames and replace with the larger lever to apply more leverage. Hold the frame and pull on it with steady, constant pressure with one hand and apply a constantly increasing amount of leverage with the other. Once one section comes detached, just continue moving around the frame. You should be ably to pry it off - at least that's what worked on my deadlights.

[rshowarth]

But butyl is a better choice here. Either the hardware store variety, or, if you can get it, the good stuff used by glass shops.

What is the name of the good stuff used by glass shops?

[Rachel]

I've picked up butyl "tape" at a glass store (real working place, not just a "decorator" place) - this was for folks at work re-bedding ports in a C & C.

Not sure how many sizes it comes in, but I got a couple of rolls - one of 1/16" x 3/8" and one of 1/8" x 3/8" - and it came in a dark color (which I didn't want - think it was dark brown or black) and in a light grey. In a big coil with paper to keep it from sticking to itself, like a thick version of double-faced tape. It's flat, not round like rope.

It wasn't too expensive either.

Is that what people here have used? Or are you using stuff from a caulk-like tube?

--- R.

[Tim]

This is conjecture based on imagination rather than any direct experience. I wonder if one way to use silicone safely on a boat is to let it cure fully before application. With the appropriate use of a mold, one could create custom gaskets that when fully cured might leave no residue on the mating surfaces. When cured I think silicone is quite stable. Is the key to not let any uncured silicone come in contact with the boat?

Silicone makes a great gasket material, and using the cured product as a gasket might make sense in some application or another. But I would see this as more of an isolation gasket than as a seal. I don't think that the silicone gasket could be called upon to provide watertight integrity, but if you wanted to build simple gaskets using cured product, say for use in installing mast hardware or some such, I suppose you could.

Still, I don't know why one would! But the cured product is indeed stable, and would not stick in the way that the uncured product does.

I was going to remove and refasten my portlights because they did not look presentable. I am having an extremely difficult time trying to remove them. So much so, I will probably seal them back up, and if they do not leak, leave them alone.

I suspect silicone.

Another unhappy possibility is that the ports were sealed with 5200. This unfortunate circumstance is far more common than we would like to hope.

In general, I think polysulfide is the best sealant choice for anything, unless the material precludes its use (i.e. Lexan, and the ABS plastics from which cheap deck plates are made). 5200, an adhesive product first and sealant second, is reserved for structural, permanent applications only.

In the few applications where polysulfide is contraindicated, I'd go with butyl: either the gross, stringy stuff from the hardware store (effective, but messy), or the butyl tape or caulk from the glass shop. Butyl is very sticky and remains perpetually flexible. One drawback is that it "creeps" over time; that is, the installation may continue to squeeze out some of the sealant as the boat moves or things expand and contract. This is a minor problem and doesn't affect the performance.

The butyl tape is very effective and easy to use, since you can handle it and press it into place easily.