CD30 Holding Tank Vent

[Steve Laume]

You could do the smaller tank without a direct discharge if you tee into the pump out and install an overboard discharge pump. This gives you the option of overboard discharge but not on an immediate basis. If your tank is close to the head this would be easy to do with the existing seacock.

Raven has a spare, board mounted, diaphragm pump. It could be used as an emergency bilge pump but is usually used to pump out the holding tank while offshore. It has a discharge hose long enough to hang overboard. The intake hose has a fitting that will screw into the pump out with a cam lock connection to fasten it to the hose.

Screw the fitting into the pump out, cam lock the hose to it, throw the discharge overboard and start pumping. Disconnect, drag both hoses overboard and pump for a while. Then drag the whole pump for a bit and you are done. I don't enjoy or indeed, do this very often but it is nice to have the option, Steve.

[Ben Coombs]

Thanks for bringing the heeling up, Stan... I had been wondering about it. I read on another boat forum that the 1" vent helps with the blockage that heeling can create.

I was looking at your photos and was curious if you cut away any hull liner to fit that system? There are about 10 different dimensions for each size tank--something to fit any space. But I thought if I cut out some liner and framed it in, there would be room for a larger tank.

Currently we are using a 2.6 gallon porta potti... two nights can fill it up (mostly because my daughter can get carried away with the flushing). Our cruising range and available time for cruising would be ok for a 6 gallon capacity, as we normally are close to lot's of pump out spots on Casco Bay. But a 12 gallon tank would be great!

[sfreihofer]

You are very astute, Ben. Yes, because of the curvature of the hull, I did cut away a triangular section of the hull liner to allow me to set the tank deeper at the forward lower corner. The triangular section is slightly larger than it needed to be, so the edges of the liner would not abrade the tank.

I used a Dremel Multi-Max to make the cuts. I then filled the cavity between the liner and the hull with Great Stuff Polyurethane foam, and pressed the tank into place while the foam was wet. The foam will not stick to the polyethylene tank, so it made a nice 'corner pocket' of foam cushion to mitigate any minor movement of the tank and avoid abrasion.

I'm sorry I didn't take a photo of it, but I'm not about to pull it all out to take a photo now!

I assume you're not talking about a CD25 installation like mine. There's no way you'd get a 12 gallon tank in there! My tank is 9 gallons, with about 6 gallons usable.

I would assume most solids will sit at the bottom, and thus help avoid clogging the vents if heeling is severe... but then again, sometimes there are 'floaters'.

Stan