What caulk to use, now that 3M 101 is no longer available, to seal the toe-rail-to-deck and hull jo

Jan 2, 2007
131
Morgan 461 St. Thomas
What caulk to use, now that 3M 101 is no longer available, to seal the
toe-rail-to-deck and hull joint (two sides)??

I used 3M 4000UV to caulk my teak toe rail both at the deck and the outside. The already-in-place toe rail sits on fiberglass. The seam of that joint, in and out (there's another on the hull side), is/was, depending on the state of disrepair, 4000UV. I need to replace it; 101 used to be the caulk of choice.

3M's 4000UV 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,
however.

An extensive conversation, at long last after chasing each other around
missing each other, with 3M's head tech guy, Todd Jessen, 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
joint).

L8R

Skip

Morgan 461 #2
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jthaw

.
Nov 7, 2015
3
Heritage W. I. 36 st pete
Skip. please let us know what you decide on.....I am caulking my toerail in same manner as you in the near future...
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
use butyl tape and be done with .....mainesail has a very good brand.....i bed everything with it
 
Jan 2, 2007
131
Morgan 461 St. Thomas
Just to be clear, removing our toe rail will not happen in my lifetime.

I appreciate all the bedding solutions, and will use them elsewhere, perhaps.

But I need to know what to use to caulk an existing joint. That is, one which won't behave as above...
 

jthaw

.
Nov 7, 2015
3
Heritage W. I. 36 st pete
What Skip said......existing toerail....need tube caulking...with UV... can't use butyl...
 
Jan 2, 2007
131
Morgan 461 St. Thomas
I can say without reservation, when I put down 101, it lasted beautifully, and were it not for some minor degradation about 9 years later which, in a fit of 'as long as we're at it, we might as well...' during our 2012 refit, caused me to dig it all out and go with the new, improved model, it would still be there I expect. Certainly all the deck hardware I bedded at the same time has what it started with...
 
Jan 6, 2010
1,520
SG,

When I painted & redid all my thru-deck fittings, I used 3M 795 caulk.

I believe it comes in colors, I used white. It's called a construction caulk but is less prone to cracking & still has some elasticity not like 5200. I would never use 5200 above the waterline or topside because of UV problems or, where I have to re-caulk over time like stanchions etc. Tow rails should not be a maintenance item.

There is also butyl tape but, I have not used this to date but from what I read, this is also good stuff but I'm unsure if this is the correct application.

CR
 
Jan 2, 2007
131
Morgan 461 St. Thomas
I actually HAVE some of that (white 795); I've also used it in black on setting replacement plexi in hatches. I also have it for rebedding ports (it's plastic-tolerant).

However, this is the first time I've heard it suggested as a caulk...

I wonder how it is to adhere to teak (it works fine to metals, glass, fiberglass, stone and maybe some others, but I don't recall anything regarding wood)...
 
Last edited:
Nov 26, 2008
1,970
Endeavour 42 Cruisin
As to using butyl tape for this application...caulk can be squeezed into deep, narrow gaps for sealing. Trying to force butyl into these gaps is very difficult.
Butyl isn't the answer for everything.

Sikaflex?
 
Jul 4, 2015
436
Hunter 34 Menominee, MI; Sturgeon Bay WI
Very disturbing; I just bedded down my seahood and lots of other stuff with 4000UV, work I never want to do again and didn't want to use 5200 in case I do.
So what would you use? Sika what?
 
Jan 2, 2007
131
Morgan 461 St. Thomas
Sikaflex 221 has been recommended by others. The problem I see is that it's in the same strength category as 5200; that would be a disaster if it ever had to come out.
 
Nov 9, 2012
2,500
Oday 192 Lake Nockamixon
I don't believe there is a 3M 795. There is, however, Dow Corning 795 Structural Adhesive. It is a silicone adhesive, which is used to glue windows into buildings, among other things. Know that using silicone will contaminate surfaces and nothing will stick until the contaminated area is physically removed. Still, it is the good stuff to use for fixed portlight installation. DC 795 is commonly available in black, bronze, and white, with many other varied colors available: http://www.dowcorning.co.jp/ja_JP/content/publishedlit/795_color_chart.pdf I swore I had seen 795 at a local hardware store some 3 or 4 years ago. Because this Beckson inspection port I have says "Only use silicone adhesive" which goes against every rule on my boat, except my replaced portlights, I decided to get some 795 for the inspection port. Went to a bunch of places, including that one hardware store, and they did not have 795. Lots of DAP and GE silicone, but no Dow Corning. I broke down and ordered a tube of white from the Amazon.
 

kito

.
Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
I was getting water intrusion from my deck/toerail joint too. First, I tightened all the bolt/nuts that mount the toerail. All of them were loose. I guess I should be spanked but I "caulked" the deck/toerail seam with Wal-Mart's Attwood 7200. I just laid a tiny bead down and smoothed it with my wet finger. It took 20 minutes to do a 30 foot boat. It's been 2 years and not a drop has leaked and has stayed fairly flexible. Maybe UV will take it's toll but it's a half hour job to fix. I do use Dow 795 for most other sealing but wasn't sure how well it would stick to gelcoat.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
it actually sticks very well to gel coat thats what they use and what i used to replace my fixed portlights .....lexan on one side and gel coat on the other side ...it's about a 30 day cure time to be fully cured but starts holding right away
 
Apr 8, 2010
2,090
Ericson Yachts Olson 34 28400 Portland OR
We have used LifeSeal, usually the clear version, for 20 years now for all above water adhesive/sealing.
No leaks or problems.
Other folks will have their own chosen goo proven by experience.... so this question has multiple "right answers".....
:)
About the only stuff I avoid is 5200 (aka "the devil's glue" !)

Loren