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Butyl tape vs SCS Silpruf for bedding chainplates

I am currently in the process of replacing standing rigging.  While the rigger prepares the new rigging I plan to re-bed the chainplates while the rigging is removed.  I have read most of the past posts on the forum on this topic and the Maine Sail detailed article on the benefits of butyl tape and the downsides of silicone.  However, my rigger has traditionally used SCS2000 Silpruf (a GE product) preceded by a thorough cleaning and application of a special primer (acetone plus some other nasty stuff), and says he’s never had a problem with it.  So I’m inclined to follow his lead as a well established and knowledgeable rigger.  

BUT. ...  Two questions:  1.  Does anyone have an opinion on the choice of bedding sealants?   2.  Since stainless can corrode in the absence of oxygen, would it actually be better not to fill the void below the chainplate with sealant?  I.e., is this another argument for butyl tape just under the chainplate cover and between the cover opening and the chainplate?  I guess the assumption is that sealant filling the whole cavity will prevent water from getting into an oxygen delpleted area.  

Thanks for any advice.  

Chachere's picture
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I have been using Mainesail's butyl tape for the past 7 years or so, and have NEVER had a leak from a bedded component where I used it.  It is easy to apply, doesn't leave a mess, and avoids having half-used and now hardened tubes of other sealant lying around.

The only caution is to make sure to follow his instructions about the incremental tightening. It WILL continue to squeeze out over time; I've seen the butyl sealant slowly migrate out even a couple of years later, so one needs to keep on top of that. 


Matthew Chachère
s/v ¡Que Chévere! #466
1985 C36 MKI tall rig fin keel M25
Homeported in eastern Long Island, NY

Catboat Willy's picture
Catboat Willy
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I second what Matt said above. GE's SCS 2000 is a pure silicone product and there are many discussions relating to silicone and ultra-violet light and the charteristics of ageing of silicone in ultra violet light (the sun). Butyl tape has many advantages plus (IMHO) much easier to use than a tube of silicone in a squeeze gun. Like Matt, I've never had a failure of any bedding project with butyl tape. You can check a discussion on Mainesail's web site for further information.

Bill Dolan 1990 Catalina C-36 MKI - Hull #1041  'Williwaw'
Std. Rig, Walk Through, Wing Keel
M35, Oberdorfer Conversion,
Home Waters; Port Charlotte, FL
'You are never out of work if you own a boat'

Siler Starum's picture
Siler Starum
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Posts: 55

I would have a look to one of the better sealant products (no silicone and also no tape) like SIKA-product together with use of a proper primer to ensure proper "adhesion" between the sealant and the (stainless steel) material. Each its self respecting sealant product has its own primer for use to different materials for achieving the best result. 
And having applied the primer to the stainless I would fill the void spaces complete with sealant to ensure that no water or moisture can collect.

Durk Nijdam
Catalina 36MKII - 2001 / hullnr. 2013
Stavoren - Holland
Last seen: 1 month 6 days ago
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Thanks very much for the replies.  I also saw a lengthy post by “three Fools” on the subject with detailed instructions.  The article recommends routing out a shallow area in the plywood between the top and bottom laminates and filling that with WEst Marine EPoxy (system 105, 205, 406).  After it cures he goes with butyl tape .  I guess the idea is to create a barrier in the wood cavity so that if there were a leak it would not migrate laterally in the deck area adjacent to the chainplate fitting.   Any comment on that?

 Also when people say they use butyl tape do they fill the cavity with it too or just the underside of the chain plate cover and the space between the cover and the chain plate as it exits the deck opening?  

Incidentall I have purchased the Catalina Direct “upgrade” to. Chainplate covers which add a short rectangular stainless wall around the chainplate opening.  I assume that get filled with bedding compound.  HOw does this idea fit with using butyl or does it?  Thanks again for any advice.

TomR's picture
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I also just bought the Catalina Direct upgraded chain plate covers. I figure they're filled to the top with butyl tape to make sure there is a tight seal in the rebed process. If anyone has rebed using these covers I also would appreciate some advice or helpful hints.


Tom Runiewicz
ObLaDi ObLaDa
Catalina 36 MkII, Wing Keel, Tall Rig
Hull #1998
North East, MD
Waxing Moon's picture
Waxing Moon
Last seen: 1 month 3 weeks ago
Joined: 2/15/17
Posts: 16

I recently noticed some rust along the plastic steps on my swim ladder. I had planned to remove the plastic steps and clean/derust.  Upon inspection I found that the steps are riveted and that water is able to enter the steal tubing which is likely the source of the rust. It looks like the only remedy is to drill out the rivets, wash out the salt, dry thuroghly, and reinstall the plastic steps. Now, rivets vs. tapping with screws?

Waxing Moon
Catalina 36 MK II # 2105
Port Charlotte, FL


Captain Moon
Waxing Moon
2002 C36 MK II #2105
Port Charlotte, FL
Maine Sail
Last seen: 2 days 8 hours ago
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Posts: 321

Please keep in mind that Bed-It Tape is not a straight butyl tape. The word "butyl" is used only because folks are familiar with the general consistency as well as to keep competitors chasing their tails. (wink)

Bed-It Tape is a hybrid product specifically formulated for bedding deck hardware. 


-Maine Sail


Last seen: 7 hours 22 min ago
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Posts: 62

Maine Sail: Bed-It Tape is a hybrid product specifically formulated for bedding deck hardware. 

And it's the Bee's Knees. ;-)

Last seen: 1 month 6 days ago
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Posts: 7

Thanks again to all who replied.  You may gag but I did go with my rigger's recommendation and used the SCS 2000 Silpruf and the Catalina Direct upgraded chain plate covers.  He was pretty persuasive that this works really well.  I gooped it heaviliy on top of the tie rod fittings before pushing them through the deck and covered the area from top of the chainplate cover "tent" to the bottom of the two chainplates extending trhough the deck. I will post a report sometime down wind and let you know how it turned out.  

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