Catalina 27 Hull/Deck joint leak

Kopite

.
Mar 11, 2015
110
Catalina 27 Monroe MI
Hi,
My 1984 boat has a leak at the joint, near midship on the starboard side. Water shows up in the pocket behind the seat cushion, not on the top shelf. The water coming in is crystal clear, ( no wood stain ) and shows up after rain. I did a quick test by adding food dye above the rub rail on a rainy day, and sure enough the water coming in shows the dye. Of course it might not be leaking at the point where it shows up, it might be forward or aft of there, but I can see it running down the hull behind the liner. It's not really a huge concern as the incoming water is nicely corralled in the pocket, and I just sponge it out after rain, but I'd like to fix it if I can. However, I'm not about to go pulling the rub rail off. I appreciate that the shoebox joint design implies the leaking water has to flow upwards, but it could also come through one of the through bolt holes. The boat does also have a small impact "dent" in the rub rail and some surface stress cracks just aft of where leak shows up, which might be an area where the seal has been compromised/damaged. I've purchased some capt tolleys and am thinking to apply to the area near the damage, ( from above only ) to see if that helps. If no change, then complete the treatment all around the boat.
Are there any other ideas, or concerns with my approach ?
Thanks, Andrew
 

caguy

.
Sep 22, 2006
4,004
Catalina, Luger C-27, Adventure 30 Marina del Rey
I have the same problem for a couple of years before figuring out it was coming in from behind the rub rail.I sealed it be above and below the rub rail with butyl caulk. Mine was coming in when the boat was heeled.
 
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Kopite

.
Mar 11, 2015
110
Catalina 27 Monroe MI
Thanks, I'll look at the caulk if the cptn tolleys isn't enough.. I was thinking just to keep the rain out, but I might need something a little more substantial when I sink the rails. ( I only got the boat recently, and haven't seen much breeze yet..)
 
Jan 12, 2013
114
Catalina C27 - Tall Rig Door County, Wis
it can come from so many spots, windows, bedding, or glass seal,or deck hardware too!
 

Kopite

.
Mar 11, 2015
110
Catalina 27 Monroe MI
Update to the post. I carefully applied a small amount of Captain Tolleys crack sealer all along the upper hull/aluminum rub rail interface, and in most areas it would sit there and dry. In one area I found it would disappear - I think it is where the boat has hit against a dock post or something. For that area a few days later I applied a very small bead of silicon, overlapping onto the area where the Tolleys would sit. That stopped my leak. A more thorough way would be to remove the rub rail and reseal all the bolts, but that would be a big project. Mine has been leak free for a while now 4 years with this "fix".
 
Oct 10, 2009
982
Catalina 27 Lake Monroe
I just sealed my stbd rubrail with Life Calk after reading this. It appears to have worked; thanks for the report!
 
Mar 14, 2021
1
Catalina 27 Standard Reefpoint Marina, Racine, WI
When caulking the rub rail did you just caulk the top, bottom to both?
 
Oct 10, 2009
982
Catalina 27 Lake Monroe
I also just did the top, figured it's pretty difficult for water to run uphill. From what I observed, it seemed like there were a couple likely spots where water was coming in; one was a deformed area of the rubrail which looked like a collision from long ago, the other directly beneath the little scupper near the forward part of the cockpit. Water just pours there directly onto the top of the rubrail.
 
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