What Caulk to Use?

[Larry M]

We are painting and re-gel-coating parts of Hobo. In the process, all of the exterior hardware including port-hole o-rings, railings, swim platform brackets, hatches, mast base, dinghy chalks, etc, will be removed (pilot house windows and doors no) When I put things back, what caulk (s) is recommended? How about UV resistance? We have used 3M 4000 UV with poor results. I know not to use 5200. Everything is gasket-ed so I am looking more for a sealant than adhesive. SikaFlex has a good following but I haven't been able to determine which one (s) would be applicable. With the exception of the swim platform brackets, everything is above the water line. So which ones would you use and have had good experience with?

 

[Keith]

I like Boatlife polysulfide for mounting stuff. Been around and used successfully since WWII. I still haven't found anything white that stands up well to UV. That 4000 UV turned to powder after a couple of years here on the Gulf Coast.

 

[RT Firefly]

Greetings,
Mr. Larry M. As a result of my recent "un bedding (UGH) and rebedding" of a hatch, I would be VERY adverse to using anything but Dolphenite (sp). NOT adhesive, flexible, user friendly and CAN EASILY BE REMOVED/REPLACED IN THE FUTURE!!!!!
Sorry, still cursing damn PO for using caulk....

 

[rwidman]

We are painting and re-gel-coating parts of Hobo. In the process, all of the exterior hardware including port-hole o-rings, railings, swim platform brackets, hatches, mast base, dinghy chalks, etc, will be removed (pilot house windows and doors no) When I put things back, what caulk (s) is recommended? How about UV resistance? We have used 3M 4000 UV with poor results. I know not to use 5200. Everything is gasket-ed so I am looking more for a sealant than adhesive. SikaFlex has a good following but I haven't been able to determine which one (s) would be applicable. With the exception of the swim platform brackets, everything is above the water line. So which ones would you use and have had good experience with?

Exactly what were your poor results with 3M 4000 UV?

Why not 3M 4200 ? It's pretty popular for that use.

 

[Marin]

On the recommendation of the experienced shipwrights on the GB owners forum we use Dolfinite for bedding that does not require any adhesive properties and Sikaflex for bedding that does.

The only thing to watch out for with Dolfinite is that it will dry out when exposed to air. So, for example, while we used it to bed the window frames on our boat, after the frame is installed and the Dolfinite has "cured" to a certain extent we run a faired seam of Polyseamseal around the edge of the joint where the frame meets the cabin side. The Poyseamseal prevents the Dolfinite from drying out from the exposed edge in.

We have started on a long-term project of removing the teak grabrails from the boat in pairs, taking them home, stripping them, and refinishing them properly. We are reinstalling them using Sikaflex because we want some adhesion in the bedding.

We have used 3M 4200 with success before we switched to Sikaflex and based on our experience I would not hesitate to recommend it if someone for some reason didn't want to use Sikaflex. I use black Lifecaulk on the tips of the deck screws I reseat but other than that I haven't been impressed with the product, at least as far as deck seams are concerned. Their bedding products may be fine but since we've had outstanding success with Sikaflex we've had no reason to try them.

 

[Phil Fill]

I am down to three:

3M 5200 – Applications I do not want to come apart of plan on taking apart.
3M 4200 - Applications I plan on taking apart.
Boatlife - Teak Deck – For the teak decks.

The other is Epoxy for things I defiantly do not want to come apart and do not intend to take a part.

Every year on the gunnel and rub rail, even the 5200 has failed, so now I first epoxy with 5200 over. Around the salon windows I epoxied so moisture/water could not get/seep in, and used 4200 to set the windows.

 

[Larry M]

...I still haven't found anything white that stands up well to UV. That 4000 UV turned to powder after a couple of years here on the Gulf Coast.

I also have had poor results with the 3M 4000 UV. It doesn't hold up in the tropics. The caulk in the picture is less than 3 years old.

 

[Larry M]

Greetings,
Mr. Larry M. As a result of my recent "un bedding (UGH) and rebedding" of a hatch, I would be VERY adverse to using anything but Dolphenite (sp). NOT adhesive, flexible, user friendly and CAN EASILY BE REMOVED/REPLACED IN THE FUTURE!!!!!
Sorry, still cursing damn PO for using caulk....

RT and Marin: I agree on the Dolfinite for windows and hatches but I'm not sure about things that flex like stanchion bases. I think I'm looking for something that some elasticity to it maybe?

 

[Marin]

I would not use Dolfinite to bed stanchion bases. I would use Sikaflex for that.

 

[Larry M]

... We are reinstalling them using Sikaflex because we want some adhesion in the bedding...

Marin: What number Sikaflex are you using?

 

[Marin]

Beats the hell out of me. It's the only one Fisheries Supply stocks on the shelf. The number 291 comes to mind but I could be misremembering that. I just bought a new tube last week for bedding the forecabin top grabrails but I just picked the tube off the shelf and didn't look at the label other than to make sure it said Sikaflex and Black.

 

[CPseudonym]

I've been re-bedding with butyl tape and am happy with the results. It's flexible and easily removable.

 

[Larry M]

Beats the hell out of me. It's the only one Fisheries Supply stocks on the shelf. The number 291 comes to mind but I could be misremembering that...

Marin: :lol: I found the Sikaflex guide and it sounds like it is the 291. The Sikaflex guide says for bedding SS fittings to use Sikaflex 205 cleaner then use the 210-T primer. From the GB forum and what you have done in the past, is everyone really using the primer and/or cleaner? We only want to do this once.

http://www.bluemoment.com/downloads/sikaflexmarinehandbook.pdf

 

[Marin]

I've never seen any reference to using the cleaner on the GB forum but that doesn't mean people aren't using it. I will pose your question to the GB folks and see what they say and let you know.

 

[Nomad Willy]

I'm using more Dolfinite now.I bedded in a plywood platform on the bow about
1 1/4" x 18" x 22". Put on plenty of Dolfinite and started turning the bolt nuts like the head studs on an engine. Tighter and tighter. There were quite a few holes from bolts in the past. I figured that would be OK. But I thought the Dolfinite was going to set up much more than it did. Months and months later every time the sun warmed up the deck more and more tan Dolfinite goo would ooze out and fall down on the bunk. Had many Dolfinite droppings on our bedding. I should probably take it up, plug the holes and re-install. I'll use the dolfinite though and taking up the plate wo'nt be much of a problem.... because I used Dolfinite. I did make a nice fat bead of 291 Sikaflex all around the base.
I plan on using some Boatlife as I hear it works better than most on teak. Frequently I use Boatlife in the very small tubes just because it comes in the small tubes and numerous sealing jobs only require a very small amount.

 

[Marin]

Dolfinite doesn't cure in the same sense that stuff like Sikaflex, 3M, etc, do. It will dry out over time if air gets to it. But I'm not suprised at the experience you had, Eric. That's kind of what Dolfinite does. Next time, don't give it a way to escape.

On the plus side, if you bed a window frame in Dolfinite and ten years later have to remove that frame to replace a broken pain or deteriorated track, the frame will come right off with no strain or forcing or risk of breaking the frame if it's wood or bending it if it's metal. Which is why we use it for these kinds of applications.

 

[Marin]

From the GB forum and what you have done in the past, is everyone really using the primer and/or cleaner? We only want to do this once.

http://www.bluemoment.com/downloads/sikaflexmarinehandbook.pdf

Here is an answer to your question from Bob Lowe, founder of the GB owners forum and probably one of the most experienced shipwrights and yard owners around.

"If you want it [Sikaflex] to stick to the surfaces then the cleaner and primer will help. However when I want to achieve this I just coat the surfaces with CPES. Works great."

 

[FF]

Eveey thing on a boat needs rebedding in time ,DOLPHINITE.

If the stanchon bases wiggle , reinforce them , or the deck or install proper blocking.

What doesnt get rebedded often enough will leak, the big reason for punky decks and PH on so many TT.

 

[Larry M]

I've been re-bedding with butyl tape and am happy with the results. It's flexible and easily removable.

I hadn't thought of the butyl tape and for some of our hardware I can see where it would be a good application. Compass Marine does a nice little write up. Thanks.
http://www.pbase.com/mainecruising/rebedding_hardware

 

[Larry M]

Eveey thing on a boat needs rebedding in time ,DOLPHINITE.

If the stanchon bases wiggle , reinforce them , or the deck or install proper blocking.

What doesnt get rebedded often enough will leak, the big reason for punky decks and PH on so many TT.

I don't have enough guts or believe Dolfinte should be used on everything. I will still use a polyurethane type caulk maybe some butyl tape where I want some adhesion and a sealant.

 

[psneeld]

I don't have enough guts or believe Dolfinte should be used on everything. I will still use a polyurethane type caulk maybe some butyl tape where I want some adhesion and a sealant.

i think bedding compounds are great for wood...but where thing constantly work...an adhesive caulk is usually preferred. I wouldn't worry about using something like 5200 on things like railings and cleats (rarely removed) that are metal...you can always add a little heat to help break the bond when you do have to remove them.

I forget which naval architect recommends it...but one of the popular ones (read prolific writer too), but he recommends all deck hardware to be epoxied down with the same thought in mind...spreading the load to more than just the fasteners and heat will release the epoxy when the time comes.

I'm redoing my windows and I think I'll do the butyl tape route...I think it will be the neatest...

 

[RT Firefly]

Greetings,
Mr. Larry M. Your fasteners SHOULD be the primary means of affixing anything to your boat as Mr. FF states. The bedding material is only there to prevent water ingress and NOT IMHO to add strength in holding stanchions, ports, mast base etc. If your fasteners fail, I wouldn't place much faith in ANY adhesive being able to do the job of intact fasteners. For sealing mating edges of house and deck or seaming teak decks, for example, YES a good caulk is the way to go but as I stated earlier, I'll NEVER use caulk for bedding EVER!
That being said, I have only recently become aware of butyl tape which I will consider using in future specific applications.

 

[psneeld]

Greetings,
Mr. Larry M. Your fasteners SHOULD be the primary means of affixing anything to your boat as Mr. FF states. The bedding material is only there to prevent water ingress and NOT IMHO to add strength in holding stanchions, ports, mast base etc. If your fasteners fail, I wouldn't place much faith in ANY adhesive being able to do the job of intact fasteners. For sealing mating edges of house and deck or seaming teak decks, for example, YES a good caulk is the way to go but as I stated earlier, I'll NEVER use caulk for bedding EVER!
That being said, I have only recently become aware of butyl tape which I will consider using in future specific applications.

while I agee the fasteners should have the strength...if they work loose...you are adding a dynamic in there that weakens the system.

 

[RT Firefly]

Greetings,
Mr. psneeld. If you're saying that Dolphinite is the dynamic that weakens the system, that's exactly my point. If the fasteners work loose, tighten them up. I do NOT feel adhesive/caulk adds to the overall strength that justifies it's use. As Mr. FF correctly pointed out, pretty well everything will fail after a time and have to be renewed. As I mentioned in a previous thread, I wished to save and re-use teak moldings around a hatch and had the devil of a time breaking the failed bond of previously applied caulk/adhesive and removing the crap that had adhered to the moldings prior to re-bedding with Dolphinite. My repair currently does not leak as it did before and I feel confident if it ever does, and I'm sure it will, I'll be able to easily remove and rebed said moldings.

 

[psneeld]

Greetings,
Mr. psneeld. If you're saying that Dolphinite is the dynamic that weakens the system, that's exactly my point. If the fasteners work loose, tighten them up. I do NOT feel adhesive/caulk adds to the overall strength that justifies it's use. As Mr. FF correctly pointed out, pretty well everything will fail after a time and have to be renewed. As I mentioned in a previous thread, I wished to save and re-use teak moldings around a hatch and had the devil of a time breaking the failed bond of previously applied caulk/adhesive and removing the crap that had adhered to the moldings prior to re-bedding with Dolphinite. My repair currently does not leak as it did before and I feel confident if it ever does, and I'm sure it will, I'll be able to easily remove and rebed said moldings.

No Dolphinite doesn't weaken anything...it just doesn't hold the components as securely as an adhesive...so things work loose and loose things have higher loads on them.

Even West Systems epoxy suggests and shows how to bed marine hardware with epoxy....they have been around the block on this one.

I would use a soft bedding compound for small wooden trim around a hatch also...but for railings, mast/davit bases, and all other constant cycle and high load joints I would use an adhesive sealant as long as the hardware was metal....so I could use heat to help soften the bond when the time came to redo/repair.

I know both sides of the coin...so I use what I think will last the longest and do the best job...but I'm sure we all have experiences that have led us to our opinions because the manufacturer's claims have fallen short of our expectations.

Plus...to tighten some hardware up...getting a tool on the backside requires that trained boa constrictor and I can't find him in the yellow pages anymore!!

 

[FF]

For folks working on their boat , one simple solution to very high stress fittings is quite simple.

Raise the sealing surface so standing or modest water will not even see the sealing.

We use GRP from a scrap boat or part removed , sometimes 1/2 thick can be found.

A removed transom may be REALLY! nice and thick.

Simply cut a pad larger than the fitting and epoxy (thickined) the pad to the deck on the outside.

Drill up from under to relocate the fastening holes from below.

Now with the item raised 1/2 or 1 inch from the deck surface , your choice of sealing goop has very little to do, till the standing water is over that 1/2 or 1 inch.

Cheap, simple and works every time!

One caution is really modern fittings stuck in with calking tape should be re bedded just with the tape.

Its cheap and a snap to remove , and really fast to R&R.

FF

 

[HopCar]

I'm with psneeld on the issue of 5200. I just installed a couple of rod holders and bedded them in 5200. It is very unlikely that I'll ever have to remove them but if I do, I'll just warm them with a heat gun or propane torch and they'll pop right off. I don't use 5200 for added structural strength, I use it because it is superior at keeping out water for long periods of time.

All joints on a boat move to some extent. My rod holders will expand slightly faster than the fiberglass deck as the sun warms them. The 5200 will adhere to both the deck and metal but will flex enough to with stand the expansion and contraction of the joint.

I do use 5200 as an adhesive in place of fasteners as well. My teak boat hook holders are glued to the fiberglass with 5200. They've been there for many years now with no screws.

 

[CPseudonym]

I hear a lot of folks talking about sealing leaks. Was taught re-bedding should be a preventative task. If the joint is leaking it sounds as though you are at least 2 seasons behind on maintenance.

If re-bedding was handled regularly to begin with there would be fewer soft decks and dry rot to deal with. I'll stick with butyl tape done skillfully, with care and look further into this Dolphinite.

Adhesive has no place on my boat for anything above the waterline that may need removal. JMHO/YMMV

 

[psneeld]

I hear a lot of folks talking about sealing leaks. Was taught re-bedding should be a preventative task. If the joint is leaking it sounds as though you are at least 2 seasons behind on maintenance.

If re-bedding was handled regularly to begin with there would be fewer soft decks and dry rot to deal with. I'll stick with butyl tape done skillfully, with care and look further into this Dolphinite.

Adhesive has no place on my boat for anything above the waterline that may need removal. JMHO/YMMV

Why would anything below the waterline require adhesive??? Or is there no place for it there either????

 

[stevensibs]

I am a big fan of Butyl rubber, both in tape form and in a tube. Silverton used it on my convertible 28 years ago, and when I removed all the deck hardware and bow rails to Awlgrip, the stuff was still soft and pliable, so I chose butyl to re-bed everything. You must not tighten down the hardware too much for a few days, to give the butyl time to set. Then after, you can re-tighten. It comes in grey and black 1/2" tape, 100' rolls, and tubes for caulking guns.