Thread: waste tank
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Old 10-11-2018, 06:12 PM   #10
Dougcole's Avatar
City: Carrabelle, FL
Country: USA
Vessel Name: Morgan
Vessel Model: '05 Mainship 40T
Join Date: Jan 2008
Posts: 1,170
I just finished installing a new 1 1/8" vent on our 400. I was inspired by Jeffery, Peggie and Don. Same deal, I was getting a puff of very foul air from the vent with every flush.

Here is a detailed description of what I did, the vent is accessed through the plate in the floor just aft of the master bed.

1. Cut the old 3/8 inch vent line and cap off. Would be better to remove it, but that would be a pain to access. Using a pipe wrench to unscrew the old vent fitting from the tank.

2. Replace with a threaded/barbed fitting. The closest I could find was a 1 1/4" fitting, but I couldn't find a 1 1/4" through hull, so I necked it down to 1 1/8 using an adapter. Attach the hose, you need about 13 feet. I used sanitation hose.

3. Slide the hose Fwd under the floor under the bed. Slide the mattress back and open the plate underneath it. Climb in and scope out the area under the FWD bulkhead. You can see where the anchor locker drain and the drain for the Fwd AC come out under there.

4. Hardest part. From outside the hull, drill a hole through the hull just aft of the anchor locker drain. I did it from my tender. Install an open through hull there, not a holding tank vent. My hull was cored there, so I coated it with epoxy and then sealed it with 4200. Climb back in to the hole under the bed and attach the fwd end of the hose using appropriate hose clamps.

Easy Peasy. I hope it works.
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