Type of caulking and bedding material

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Oct 1, 2010
We are redoing our teak and have removed some pieces to refinish.* What product do we use when we reinstall the screws and bolts?

There are lots of gaps between the teak trim and fiberglass.* After the teak trim is finished, what type of caulking should we use?

We have teak trim along the bottom of our flybridge.* It is grey and seems to retain some moisture as it is in the path of water (when we hose the flybridge)* Lately it is the driest we have seen it and would like to finish it and caulk so that the moisture stays away from the trim.* Any suggestions would be most appreciated.

We are redoing all our brightwork with Cetol Natural teak.* Our boat is a 1986 Monk36.
Boat Life makes a caulking for teak decking that holds up to the oil in the teak wood and the teak oils. That is what in used *13 years ago when I refastened and re caulked the deck seams.* I used stainless steel nuts/bolts and screws.* To cover the screw bolts you can buy bungs/teak plugs.*

If the screw holes are to big you can fill them with West System epoxy with one of the addtives to thicken.

** Mr. Rusbet.* Welcome to TF.* If replacing teak TRIM pieces, I use Dolfinite** http://www.jamestowndistributors.com/userportal/show_product.do?pid=4400
** It is NOT caulking.* It is a bedding compound which is VERY user friendly and CAN be removed, if necessary, very easily.* SS or bronze fasteners would be the preferred method of attachment.*
* P/F, read the man's question.* He's dealing with brightwork (TRIM, not DECKING).
I use Boat Live teak caulking on trim also as its made to hold up to the teak oils.*and also use 3M 5200*for some applications.* 5200 is easier to work with and clean up as paint thinner will take 5200 off before it dries.* Tape the area and the best applicator is your index finger

RTF, thanks for point it out.**
4200 if you ever want to get the item off again without damage to it or what ever it is secured to.* 4200 is much*the same as 5200 except it is removable.
Yes Dolfinite is great. But mostly only as a bedding compound** ..not a caulk.
Phil Fill,
Thanks re: the Boat Life as I've been wondering if I was in for trouble w caulking and all the linseed oil I've been using.
I've had bad experience w 4200. I use SikaFlex now for most caulking. 5200 when I want to weld it together. Think I'll look into Boat Life.
I use SikaFlex for caulking teak to fiberglass. It has worked out good for me.
For sealing screws and most anything else I use 5200.
(I have always been able to get things apart after sealing with 5200.)
rusbet wrote:

1. We are redoing our teak and have removed some pieces to refinish.* What product do we use when we reinstall the screws and bolts?

2. There are lots of gaps between the teak trim and fiberglass.* After the teak trim is finished, what type of caulking should we use?
1.* We don't use anything when replacing screws and bolts except deck screws through the teak planking.* For them a very experienced shipwright we met advised us to dip the end of the screw in sealant before installing it.* But fasteners that hold things like trim to the boat are sealed by the bedding compound or sealant that is bedding the trim or other component.

2.* Again going on the advice of shipwrights we've met, we use Dolfinite when bedding things like teak trim strips, window frames, etc. to the exterior of the boat.* It makes removal at a later date extremely easy.* It's available in "natural" (tan) or white.* For bedding glass, window track, etc., we use Sikaflex.* One material we NEVER use on our boat for bedding or sealing purposes is silicone except for a few very specific uses in the engine room.

PS.* Eric--- We've used LifeCaulk on our boat for various things over the years and not been impressed with it.* If exposed to the weather, LifeCalk seems to break down over time to the point where rubbing your finger over it leaves long black streaks on the adjacent fiberglass, paint, wood, and your finger.* We find that Dolfinite is best for bedding, Sikaflex is best where a sealant/adhesive is needed, and TDS is superior as a deck plank caulk to anything else on the planet.

I'm talking about applications above the waterline here.* I've had no experience using sealants below the waterline.

-- Edited by Marin on Wednesday 5th of January 2011 12:49:08 PM
A long long time ago I thought silicone was great. I made a plywood self bailing engine well for my big OB boat and caulked it up the best way I knew how. A couple of months later I noticed a little spot where it seemed to have come loose and I gently pulled on it.
The entire caulk job came off w almost no effort at all. Just pulled it all off in less than a minute. It seems silicone only adheres to slick plastics, glass and metal. It's great for making fish tanks but I don't trust it any more.
Moondance wrote:

I'm curious, why not ever Silicone caulk.
If silicone gets on anything, and particularly finish surfaces like paint, gelcoat, brightwork, or onto raw wood it will prove to be almost impossible to repair or redo the finishes on these surfaces in the future without removing a lot of material.* Nothing will adhere properly to a surface that has even a trace of silicone on it.

Given that there are so many other adhesive sealants on the market that perform as well or better than silicone without the finish adhesion problem there is no reason to use silicone as a bedding/sealing/adhesion compound.

The only use we have for it is on impeller pumps (raw water pumps, for example) in case it proves difficult to get a leak-proof seal between the cover plate and the pump body using the gasket alone.* However I believe we've only had to resort to this once.* But outside of this, in my opinion (reinforced by the shipwrights on the Grand Banks owners forum) silicone has no place on a boat.

It's not that it doesn't work as advertised.* It does, although Eric has described an instance when it didn't.* But the side effects of using it can be detrimental.


-- Edited by Marin on Thursday 6th of January 2011 01:52:34 PM
I'm still looking for a good, non-silicone, white outdoor caulk that will stand up to the sun. I tried the UV-xxx silicone that's supposed to work well for that, but it turned to chalk after a couple of years. Lifecaulk doesn't last in the sun. Don't really want to use 4200, but would consider it if it'll work. Any other ideas?

Is this an era of minimalization?
Sikaflex 291? Is that the one? *They also have a fast cure. *The 3M looks good, too.

-- Edited by Moondance on Saturday 8th of January 2011 06:01:45 PM
Yes 291 "adhesive/sealant and bedding compound"

-- Edited by nomadwilly on Saturday 8th of January 2011 06:45:34 PM
RT, that's the stuff that I thought would be the answer, but at least here with the batch I used, it basically turned to chalky crud in about 3 years. You can knock it off with a fingertip. Maybe I got a bad batch, but it's been the worst performer yet.
RUSBET! GREAT see you over here on Trawlerforum!! I think you will love this site! Great folks here.

TF friends- Rusbet and I have corresponded a little bit from another Monk site that I used to be on. I sent her the link and believe it or not, even mentioned you guys are occasionally helpful!!


Welcome to trawler forum Rusbet! Take a look around and this is the type of site I was trying to explain to the MOA....great sense of community and helpfulness here.

-- Edited by Woodsong on Tuesday 18th of January 2011 08:02:29 PM
I used a non-5200 3M product. Can't remember if it was 4200 or 4000 but it was UV.
I do remember that quickly failed. Sikaflex 291 seems to adhere and seal very well.
Sealers and adhesives work like paints and other coatings**** ....only as good as the prep.
I probably used the 3M 4000/4200 where someone had used silicone before or some other thing bad for adhesion and it did'nt stay. Standard prepping procedures probably aren't enough in some cases. Hard to explain Keith's experience though but I'll bet it's probably not the product's fault. Some other variable did it in. But I guess I'm not doing as I preach as I'm using Sikaflex now and not the 3-M.
** Should have said 3M 4000 UV.* I've used it in the past for teak decking to house joints and it "seems" fine.* Stays bright white.

3M ManufacturingÂ*| 3M United States

-- Edited by RT Firefly on Saturday 8th of January 2011 12:59:09 PM

I used 3M 4000UV to caulk my teak toe rail both at the deck and the outside.

It has failed miserably:

Makes a wet residue after rain or washing with plain water, sometimes
feeling about like freshly laid caulk

Peels off in strips, or

Falls off in chunks [segments of the caulk line, complete]

Crazes and chalks, and

perhaps others related to cleaning with water (only) which I don’t recall,
as the admiral does that.

I called the tech support desk; that guy gave me the number for the head
technical guy at 3M; every call resulted in being directed to voice mail,

An extensive conversation, at long last after chasing each other around
missing each other, with 3M's head tech guy established:

My preparation (remove all old caulk, light sand in the chamfered opening I
cut into it for deeper penetration into any gaps under the toe rail, blow
out, scrub with acetone and allow to dry, tape toe rail and deck/hull) was
as good as it gets

Application was perfect (caulk, immediately tool with caulk tool, lift
tape) - I had two people helping in order to do all this while it was fresh)

Cure time and environment was appropriate.

After which, he admitted that they had had a "formulation problem" with
4000UV that they were still trying to sort out.

He said, but has walked back that offer, that he'd provide a form for me to
take to allow a merchant to be reimbursed, and that I should redo it with a
competitor's product.

A variety of emails have passed, attempting to pin him down as to what we
should do about that. He's understandably reluctant to do that, but He
wasn't specific as to what to buy, other than saying he thought Sika had a
good product for that application.

But the fact that he told me not to go back with new 4000UV, free or not,
that they were still working out kinks in the formulation, says volumes.

That I've seen exactly my complaint in many places merely confirms that I am
neither alone, nor inadequate in my use of the product. That he'd go to the
length of telling me to buy a competitive product is honorable in the
extreme, but I'm a bit surprised that he didn’t leap on the chance to have
me present a good-fer (not even a mosquito on an elephant's butt in the
scheme of things for 3M) to make the ultimate tone of this a bit sweeter
("3M Tech Support Rocks! Details at 11!)

So, when we again reach shore, we'll be digging out all that soggy or
brittle stuff, and starting over with something else. At this time, the
'something else' is under review, as not much of anything sounds good or
without problems for the application we have (sealing a fiberglass-to-teak



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I wouldn't recommend 3M 4000 UV also. The stuff does not last in the sun from my experience. I'm not sure what the UV stands for?

Here's a picture of the caulk less than 3 years old.


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I have used a few hundred tubes of Loctite Black PL on the boat and around the house. It is good for outdoors in the sun and rain.
Hdepot sells this for about $5.
Loctite PL S30 Polyurethane Roof & Flashing Sealant from Loctite Adhesives

It is a soft rubber, softer than 5200, totally waterproof, I have used it underwater seams and thru hulls.
I have to someday reseal some teak. I might use this, or I might use Black DynaFLEX 230 caulk. I might use both. I certainly wont use something that costs twice as much which is not twice as good.

Dynaflex comes in many colors. I could get dark brown or light tan. Black is traditional, but does not have to be black.
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I have used TDS SIS440 for all teak deck bedding and caulking, it is slow curing but beautiful stuff to work with. Deck hardware on FG or wood I use a product called permagum which is a wee bit better than butyl, comes in a loaf and be had from most marine HVAC suppliers. You'll get years and most likely decades out of it..........old school, but lasts

As far as 3M? It's ok, messy as hell but ok. Rule of thumb is 5200 below waterline 4200 above.
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I will admit my experience with 3M 4000UV was going on 10 years ago so in light of recent member's experience I would cross that material off the "to use" list.
All boats will eventually spring a leak somewhere.

Around hatches ans windows deck fittings is common.

" I noticed a little spot where it seemed to have come loose and I gently pulled on it.
The entire caulk job came off w almost no effort at all. Just pulled it all off in less than a minute."

This seal then easily peal is Great for temporary repairs .

You can stop the leak and in 6 months or a year when you "getaroundtoit" the repair is easy to clean up .

Not all sealing wants to be "forever".

The same leak could have been repaired with 5200 but a chisel not your fingertips might be needed to begin a real repair.

I LOVE silicone as it expands my time before I must repair a leak.
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