Installing a New Vent for Waste Tanks

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I just found a vent that I think will solve my waste holding tank non-venting issues for my 34 Mk II at Catalina Direct.   It looks like it will work fine--it's one that is now being used on a variety of Catalina sail boats: C-28, 320 and C-42's.  Has anyone else added one of these vents to increase air circulation for their holding tank?   

CD's suggestion is to mount the vent just below the rub rail--I'm figuring on that location and virtually inline with the existing stanchion at about the "stripes level."  Does anyone know how thick the hull is at this point?  I'd like to have an idea how thick the hull is before I start drilling it out and installing the new fitting.

Chuck Philips
#1725 AMB Marina,Long Beach
Chuck Philips
"Forever Young"
2005 Catalina 34--#1725--Anniversary Edition


I did this exact thing on my '89 Mk1 last year.  i don't know how similar the hulls are.  on mine the strip under the rub rail is pretty thick, but it was semi hollow.  it was about an inch if i recall correctly.  i believe (at least on the mk1's) this the strip is the lower edge of the shoe-box joint between the upper and lower hull molds.  i bored the hole out with a hole saw and filled the small void with thickened epoxy.  it was super scary to cut the hole, but seems to have worked out
1989 Cat34 #856, original m-25xp

Dave Spencer

I added a second holding tank vent in 2012.,6861.msg45888.html#msg45888
I think there are some other projects like this documented on the site... do a search and you'll likely see a few samples.  Some have suggested running the hose farther forward into the chest of drawers in the V berth but that seems unnecessarily complex to me (plus I didn't think of it at the time.) 
Good luck with your project.  Let us know how it turns out.

Dave Spencer
C34 #1279  "Good Idea"
Mk 1.5, Std Rig, Wing Keel, M35A Engine
Boat - Midland, Ontario (formerly Lion's Head)
People - London, Ontario

Stu Jackson


From the 101 Topics, which is why they are there. :D

Second Holding Tank Vent,6861.15.html
Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  Cowichan Bay, BC  Maple Bay Marina  SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."