Broken flange at deck hull joint

[RWarren]

Hey guys,

This is my first post but I have enjoyed reading the other posts here for a couple of months now.  I purchased by first boat, a 1981 CP16, about 6 weeks ago and have been doing some cleaning and basic modifications as I leaned the ropes in light wind on a local lake.  I hope to find more wind along the intercoastal waterway of N.C. next weekend.  The boat seems to be water tight and is in good condition over all but I know I need to clean and reseal the hull joint on such an old boat.  A preliminary inspection revealed that it  has some rivets that have broken out and the flange is broken in a couple of spots that I can see without totally removing the rub rail.  Will 3M 5200 alone be strong enough to make a suitable repair or do I need to rebuild or cover over the broken areas with fiberglass?  I have many more questions, but that is the starting point.  If anyone has experience with this, I would appreciate any advice you may have.

Thanks a bunch!

Ricky

[mike gartland]

Ricky,

I needed to do some repairs to the hull-deck  flange on my CP-23/3 where it was leaking in the vicinity of the starboard shroud chain plates.

After pulling the black vinyl rubrail I found the old white duct tape completely disintegrated and a number of gaps in the hull-deck joint where it "puckerd" in several places.  My flange is bolted rather than riveted.  I decided that the puckering could only be remedied with additional bolts.  I ended up drilling and adding ss bolts at  the midpoints of all the existing bolts in the problem area, then cleaned the exposed outer joint surface with 3M Adhesive Remover, applied a new coat of 3M 5200 along the entire seam, covered that with a layer of Gorilla duct tape (really "industrial strength" stuff) then repalced the vinyl rub rail.  I've had no leaks ever since and that is saying something with all the torrential rain storms we get here along the Gulf coast as well as drenching spray from many good hard sailing days.

I can't speak for the fibreglass repairs as it wan't a problem in my case.  Good luck with the repairs.

Mike

[Paul]

Ricky:

Yea, the hull deck joint will probably be worse for wear on a used CP16 of such age. Yes, 5200 is strong enough for that repair.  Good luck with the rubrail.

It's OK to replace rivets with new rivets.  Just try to match the size.

Paul

[Craig Weis]

On the deck-hull joint I would peel all that stuff off down to the damaged area in order to clean-up the fiberglass and drill out any broken rivets. Are these steel or aluminum rivets? I don't know.

Vacuum the dust and wipe down the area with some denatured alcohol then mix up some two part epoxy resin and brush the area top/bottom/ and if you can inside or between the joint. Drive a wedge in there if you have to split the hull joint apart to open to fill...remove the wedge to let the epoxy squish out. 

Pot life would be about 10 to 15 minutes on the mix. Clean up both sides of the repair before this stuff gets too hard. Redrill the rivet holes through the new epoxy. Re-rivet. Put the rubber back with 3-M trim adhesive contact cement.

Or if you can find it buy a tube of PLEXUS and a hand squeeze application gun. This stuff is like iron. I used it to fill my 'Sampson post' and to secure my stainless steel tube cross piece. skip.

[arw-16]

Great information.  Thanks guys.  I really value this web site resource.  It has already saved me a couple of times.  The thing that really concerns me about my repair is that I think the flange is also broken at the corner of the transom and aft starboard where the bracket and bolts hold the rub rail tight.  The other couple of areas, all on the starboard side, the flange is weak and the rivets have pulled through leaving larger rivet holes.  My initial thought was to wrap the entire joint in a fabric strip with resin after sealing with 3M 5200.  I was however concerned about the possible need for the joint to flex and absorb impacts, so I like the ideas you have posted here better.

Thanks again.

Ricky

[B.Hart]

Skip is right on abuot that plexus. They use it to bond tables in to fiberglass pools.

[Craig Weis]

arw-16 rick,
The idea of the flange between the hull and deck and 360 deg around the whole darn boat is a ridgit flange.

It will not nor was it ever intended to absorb anything but punishment.

No flex, No give. That is the job of the rubber rub rail and the metal corner caps.
So goop her up after a good cleaning with resin and re-drill and re-rivet the thing back together. skip.