Rebedding a chainplate with butyl rubber - questions and concerns

[Bob K]

It's time to rebed a leaking chainplate, and I'm thinking of using butyl rubber instead of my usual polysulfide with hope that it will last longer.  I'm not sure if this will work though.  I'm looking for tips/ advice for this job. 

I saw Mainesail's excellent write-up on rebedding stanchions with butyl tape, and that seems like a fairly straightforward process.  Chainplates, on the other hand, have a gap surrounding them and the deck cutout.  This is normally filled with polysulfide (or whatever your  choice of goop is) prior to bedding and screwing down the rectangular deckplate.  So what is the best way to fill this gap with butyl rubber?  My plan is to clean out the gap as best as I can and then fill by cramming bits of butyl tape into the gaps until it is filled and flush with the deck (easier said than done?). Then I will bed the deckplate over top of this with strips of tape in a similar fashion as Mainesail outlined for  stanchion bases.  Since there is a also a small gap between the chainplate and the deckplate, some butyl will be visible, and exposed to the sun.  I assume (hope) it is UV resistant, as butyl rubber is used in roofing.

I am concerned that the two screws which secure the deckplate to the deck will not exert enough pressure to adequately squeeze the butyl , and  I may end up with stripped holes.   I already use oversize screws  here.

I am also concerned that the butyl might not stick well to the chainplate, because the pressure is not directly on (orthogonal to) the chainplate, but rather is downward (parallel to the chainplate).

So as I write this, I am starting to convince myself that butyl might not work for this application.  Anyone have any thoughts to share?  Maybe I'll be the guinea pig?

[gwp]

Bob...just finished rebedding  mine as well as other deck hdwr. Maybe butyl is ok but I am a believer in polysulfide..."boatlife" to be specific. I recommend blue taping underside and filling with epoxy and redrilling all holes including bolts and small 2 screws. It is a simple job and make sure you don't seal underside!  If it ever does leak...alow water to freely drain into cabin and not into deck core. All this is covered in tech site. Good luck

[mainesail]

32 years, 6 chain plates, ZERO leaks... butyl rubber....



Zero corrosion too..


Dry after 32 years..


Guess what I re-bedded them with...

[cmainprize]

Hi Bob
I have used butyl tape on the chainplates and everything else I can think of.  I really like it on hardware that is subject to movement, like stanchions, and chainplates.  It stretches and flexes and maintains it's seal.  It's also really easy to work with.  It's important to remember to only seal the outside of the chainplate, I read a post on this site detailing this task and they sealed the inside as well. 
My first choice is always butyl tape, but that's just me. 

[Stu Jackson]

It's important to remember to only seal the outside of the chainplate, I read a post on this site detailing this task and they sealed the inside as well. 

Cory, you're right, the tech wiki shows sealant inside, too.  It's just plain wrong.

[Steve McGill]

Folks,

What is your experience using butyl tape and the suns UV. I ask because I am planning to re-bed my chain plates this year as part of my normal maintenance. Normally I would use polysulfide. As you are all aware we do some have some expose area to UV because of how our chain plates pass thru the deck and the cover plate.

Thanks,

Steve

[cmainprize]

Hi Steve
From my experience, the sun is a non factor.  The stuff never seems to get hard, crack or dry out.  Builders like CS and C&C used it exclusively on all their boats.  We see these boats all the time in Canada and I can attest to how good this stuff is.  A C&C guy got me started on the stuff and I now I try and use it first for everything.  When I did my chainplates, I just packed the tape in and around the chainplate, put the cover on and screwed it down.  Some of it squished out the top opening and I just shaped it with my thumb and have never touched it since.  I use and exacto knife to trim the excess that squishes out the sides.  It is fast, easy, clean, effective and cheap.  I know I sound like a sales rep for the stuff, but I really so think it is the best product you can use.

[Fuzzy]

Who sells/where do you buy the butyl tape??
Thanks, Larry

[pablosgirl]

Hi Fuzzy,

Contact Mainsail by email, he sells the stuff.  Here is a link http://c34.org/bbs/index.php/topic,6031.0.html to another butyl rubber re bedding thread that contains links to how to's.  I bought the stuff and it is a whole lot easier to work with than polysulfied calk.

Paul

[Bob K]

Wow!!!   I'm pleased see others have been successful.    Thankis for all the input.

[togve]

Great post with lots of detail.

I have just redesigned new chain plates for the C34. Have a look at this posting.
http://c34.org/bbs/index.php/topic,6304.0.html

Cheers:

[Bob K]

So far I've rebedded two chainplates and a stanchion with butyl rubber.  Good initial results, though time will tell.  Somewhat tricky to work with as it is so sticky, but after the first one it went easier.  It was nice to not have to clean up the usual polysulfide mess.  Chainplate cover screws were strong enough to compress the rubber, though I will tighten a bit more after summer heat softens the rubber and lets it flow easier.

[Andrew Harvey]

Butyl tape is also available at any masonary supply outlet, it is used for holding stacked landscape brick pavers together.
10 bucks for a roll!

[mainesail]

Butyl tape is also available at any masonary supply outlet, it is used for holding stacked landscape brick pavers together.
10 bucks for a roll!

You need to be careful with what "butyl" you get. Masonry butyl, much like RV butyl is NOT the same stuff that was used by many builders back when butyl was widely used. I have had three rolls of "butyl" sent to me by customers two of which were not even butyl but rather a "putty" and one which was so solvent rich it had melted and deformed in the box. I tested over 14 different sources of butyl from various manufacturers and there is a VAST difference in the quality, elongation and durometer/density rating as well as working temp range. All butyl tape is NOT the same so buyer beware as you may not even get "butyl" of the quality you get may not survive long in the marine environment.

This is just one corespondence with one customer who bought the wrong butyl..

"Hello Maine,

Got the butyl rubber in time. Thanks for making the special trip!

Not that I didn't believe you, but I wanted to check out the two tapes myself. They are two totally different materials. I will be tossing the butyl rubber I bought previously. If you'll excuse the lousy video, I think you'll spot your tape.



https://picasaweb.google.com/rmcgill11/NotAllButylRubberIsTheSame?authkey=Gv1sRgCLDbjJn1-5mVmQE#5606294158195187106

Thanks for the great product and for your technical tips.

Have a great weekend.

Bob"



PLEASE before doing all that HARD work watch the video my customer made. My tape is the stuff on the left the other stuff is RV grade... Like many things in life you often do get what you pay for..

[Indian Falls]

http://www.pplmotorhomes.com/parts/caulks-sealants/48463.htm

This 1'' wide 3/16'' thick whitish color not gray, not appliance white was only 6.08 per 20' roll.  I bought 2 in-case someone at the marina needs a little.

It is intended to be used on white rubber RV roofs.  This stuff will stick to anything and it's not wet, greasy, runny, or anything.  It is just like chewing gum. 

I plan on using it to bed everything and even use it as an alternative to that emasculating ''museum wax''.