C34 mark 2 chain plates leaking - Chainplate flix

[Mike Hall]

I am currently looking at buying a C34 MK.2 , Hull no. 1330 , "Sereno" located at Auckland New Zealand. I have read some postings on problems that can occur with the chain plates. I have inspected the chain plate fixings inside and they all look well sealed, with no evidence of leaking. On the deck some silicone has been used on several  chain plate fixtures. The  questions I have are : is the deck area where the fittings go through composite ? i.e plywood sandwich & grp or solid grp like the newer models ?.
Also is this problem wide spread on all C34,s ? . I look forward to some owner feedback, regards Mike Hall.

[cmainprize]

The area around the chainplates is cored.  A half decent survey should tell you if the area is suffering from any water intrusion.  My personal project this winter is too remove all fittings and seal the deck core wtih the standard drill oversize, fill and re drill method.  My rough count was almost 250 holes to do.

[Stu Jackson]

It appears that my PO sealed the deck openings.  This is my forward lower, port side opening.  I just rebedded this one last week with butyl tape.

If your core is dry, you needn't drill it out and epoxy it, just epoxy over the plywood with a couple of layers.

The "crap" you see on the inside of the deck was from my improper bedding last time --- I sealed inside, too.  BIG mistake.  Don't do it.  Just seal the outside.  If it leaks down below, you NEED to know it.

I'm simply the "test bed dummie" for these kinda things.  FWIW, the very good chainplate rebedding article in the wiki is also wrong - sealant is shown inside, too.  NOT!

[mregan]

I just did last week what Stu suggested.  Removed the plates, oversized the bolts holes and filled with epoxy then drilled out correct size.  In the rectangular slots, used small brush to brush on epoxy to seal the core.  Then used butyl tape only on the exterior.

[Mark Sutherland]

mregan, what type/brand of epoxy did you use?  Thanks

[mregan]

I used the West System 2 part.  I'm usually not doing too much epoxying so I'll buy these 4oz bottles below and mix a little at a time for whatever I need.

http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=14974&catalogId=10001&langId=-1&storeId=11151&storeNum=50218&subdeptNum=50219&classNum=50220#.ULgLkIXXqHA

You may also want to look at the Six10.  Comes in a caulk gun tube.  Might be easier to fill the bolt holes.  I find when using the 2 part above, can sometimes get messy trying to get it into the plastic syringes to squirt in the holes.  After you fill the holes with the Six10, you could probably squirt a clump into a small cup and use a brush to coat the insides of the rectangular holes.

http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=14969&catalogId=10001&langId=-1&storeId=11151&storeNum=50218&subdeptNum=50219&classNum=50225#.ULgMDIXXqHA

[Clay Greene]

The west 610 works great.  I've used it to fill holes when replacing a cabintop winch and when used the same tube a year later when we replaced the starboard line clutch.  I just had to buy a new mixing attachment. 

I think the question about the chainplates is not if they are going to leak but when.  The top plate does not keep the water out.  You are dependent on whatever sealant is used and sealants, particularly silicone, are going to fail.  I rebedded with butyl tape and hope it is going to do a better job.  But you should consider it to be part of your maintenance plan.  The good news is that it is not a hard or particularly time-consuming job. 

[Stu Jackson]

claygr is right.

Here are pictures of the butyl tape "at work."

Held through a tremendous amount of rain the past few days.

When you do them, you should remove the plate below and assure that there is no intrusion, per the earlier picture I posted "looking up" through the hole.

There are simply two avenues for the water to enter:  the long side of the through bolt, and the short side.   

I stuffed the sides with the butyl tape and then slathered the cover plate with tape before I screwed it back in (as well as doing a "Maine Sail" on the bolt head).

I've read many posts on other boating forums about how folks use 5200 for this.  That is simply: Dumber Than dirt.  Chainplates SHOULD move a bit and let the deck flex WITHOUT CREATING LEAKS.  Why?  Look at the design of the chainplate SYSTEM.  The shrouds attach to the chainplates which, in turn down below, are connected to the rods that go even further below to the boat structure.  If the deck can't flex because some a$$hole used 5200 to GLUE the deck to the chainplate, there is more risk for failure at the point where they meet.


[chainplate butyl] [chainplate flix]

[Stu Jackson]

I also removed the long tie rod down below and replaced all the lock washers, which had evidence of water, 'cuz they were rusted!  

You can see the water stains, which I cleaned up after I took this picture.

[2ndwish]

We are in the process of rebedding the chainplates. Most of the thru-bolts on the deck came loose, but two of them are stubbornly stuck. We snapped a 3/8" screwdriver (US made) trying to loosen one. Hit it with blaster last weekend and will try again today. Any suggestions? We may have to cut them off.

Side note- since the bolts had been leaking and turned, we made a temporary seal over and around the screw  heads and washers from butyl tape. It was dry the next day after a heavy overnight rain. Not ABYC, but works in a pinch.

[Stu Jackson]

We are in the process of rebedding the chainplates. Most of the thru-bolts on the deck came loose, but two of them are stubbornly stuck. We snapped a 3/8" screwdriver (US made) trying to loosen one. Hit it with blaster last weekend and will try again today. Any suggestions? We may have to cut them off.

Not sure I understand.  The through bolts are screws that go into the acorn nuts down below.  Could you not get the acorn nuts off from down below?

[2ndwish]

Correct. The acorn nuts are quite stuck to the deck bolts

[Clay Greene]

Did you try heat on the acorn nuts?

[Craig Illman]

An electric impact wrench might give you enough shock torque to loosen the nuts. That's what I used on a couple of mine.

Craig

[2ndwish]

We were concerned about using the torch so close to the interior laminate. Don't have an electric impact wrench- maybe next year.. Ended up using an angle grinder and a cutoff wheel, cutting straight up the nut. About 80% of the way through, the nut came loose. Same held true for both stuck nuts. Likely the heat from the cutting that loosened it. Bedded the chainplate using Butyl tape in much the manner pictured above.

After replacing the top plate, there was much squeeze out. I cut way the excess on the outer part of the plate, but left the excess where the chainplate  penetrates the top plate. I tried to form it into a fillet. Is that how others handle that joint?