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Chain Plates

Has anyone done a thorough inspection of the chain plates on the C&C 99?  If so what did you find, how did you go about it, problems encountered and solutions developed.

 

Rod

Rod,

Very difficult to "inspect" the chainplates owing to their location.  Ab out 12 y ago, we broke a chainplate while under sail.  Saved the rig by making a v rapid turn into the wind.  Thanks to the big rudder/short turning radius!

Anyway, when C&C came to Hampton to replace both chainplates (under warranty; took them 2 months to get down there though) the inspection showed the the weld between the actual plate and the threaded SS rod was very minimal.  The discoloration made by the heat of welding only reached about 1-1.5 mm into the center of the joint. Hardly sufficient given the loads.

We have had no issues after the replacement which is good news.  No obvious signs of rust on the underside of the deck. That's about the only way to inspect, short of deep X-ray of the joint, perhaps.

I am hoping that after the early versions of the plates were built, that C&C improved the steel and weld quality to obviate such breakage down the road.

D.

Hi Rod,

99 chain plates are stainless steel with coated steel brackets.  Fastened to FRP (fiber reinforced plastic) bonded /tabbed knees.  Look for evidence of any corrosion or leaks.  Not much to examine here except for bonding and tabbing failures.  Hope this helps.

 

Thanks for the response guys I will have a good look around.

 

Rod

Hi Rod,  One of mine failed last year,  and i needed to get them remade locally.   Mine failed where the Rod comes in contact with the steal backing plate. I believe the combination of built up moisture and maybe an external leak which ran down the support( i never saw a leak) cause corrosion right at the baking plate.   I posted pictures last year.  I am not sure I or a surveyor would have found this on inspection.  My recommendation would be to try to look at the backing plate for rust.   when i did remove them i did find hairline cracks where the rod meet the deck plate,  can post pics if any one is interested.

Kevin

 

Thanks Kevin pictures would be appreciated.  Not sure if you posted on the forum if so I couldn't find it. perhaps it was on Facebook.  I just noticed a bit of rust type discoloration on the plate on deck.  It may be just discoloration as stainless does that but I was planning on taking them off and re-bedding but that may be a bigger job than it seems.  No evidence of any leaks though.

Rod

 

 

To all 99 owners,

This past Wednesday as we were sailing upwind in Norfolk Harbor in 14 kn breeze, the port chainplate on Kingfisher snapped and we lost our rig.  No on was hurt thank goodness.  This is the second time in 10 y (see above) this has happened.  Once again, the chainplate shows an inferior weld between the vertical plate where the shrouds attach and the horizontal plate on the deck surface.  After our incident 10 y ago, I routinely examine the chainplates every time I wash the deck, which is frequently.  I saw no evidence of any corrosion.  Sailing colleagues who work as welders at the US Naval shipyard in Newport News have also looked at the broken weld.  They have independently stated the weld was inferior.  There was very little weld material at the joint and according to one the joint was never prepared correctly prior to welding.  There was no way I could see any of this. Ten y ago I was figuring this was a one-off manufacturing defect.  Now I don't think so.  (Fool me once...)

To fellow 99 owners, I have to caution all of you to be wary of these chainplates.  I would hate to hear of any other rigs crashing down and people getting injured.  And I have to imagine that other boats out there may have chainplates of substandard construction.

We have had divers recover the mast, shrouds and broken chainplate in advance of an insurance marine surveyor rendering judgement.

If I can resurrect Kingfisher (and I certainly plan to do so) I am not going to rely on the inferior, welded chainplates supplied by C&C.  Heck, I probably couldn't find any after all these years. I will seek to find another way.

Man...between the keel bolt torques and now this, it just hasn't been much of a season.  Only won 1 race.

Please be wary of your chainplates owners.  Best of luck.

Dixon

Thanks Dixon much appreciated, will try and pass it on.

Additional info courtesy Tim Jackett:

Rod,

 

"From an inspection standpoint;

  1. Look for any signs of corrosion or crevice cracks where the vertical tang is welded to the base plate
  2. The weld should be a 1/4" fillet weld,  if it is less than a 1/4" fillet weld the chainplate should be rebuilt or replaced, sketch attached.  
  3. If building a new chain plate, the spec should include passing the vertical tang through the base plate, plug weld the vertical tang to the base plate on the underside of the base plate and do a full penetration weld on the top side of the vertical tang to the base plate and finish with a full 1/4" fillet weld between the vertical tang and the base plate. 

         Regards,

        Timothy Jackett

        O;  (440)392-2628

        C;  (440)463-2890"

Uploaded files:

More info here: https://cnc99class.com/wp-content/uploads/2021/09/99ChainplateFailurePt2.zip

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