Dougcole
Guru
Sevee,
The holding tank vent on the Mainship 400 comes out of the front of the tank (bow end). It's accessible from the small floor hatch in the V berth. It goes forward on a 90 degree fitting, then goes to starboard, then turns toward the stern under the floor of the bathroom, then goes behind the air conditioner, turns to starboard again, goes up the gunwale to the vent. Makes sense, huh?
I've never seen a more ineffective and poorly designed system.
Remove it all and run a vent forward, straight, no major bends, slightly uphill, 1" line, next to the anchor locker drain.
Here's a picture of what my 90 degree fitting looked like. PLUGGED! The picture doesn't show that it's totally plugged at the bottom. Really really smelled foul!
Jeffrey Guttenberger
R Time
2005 Mainship 400
View attachment 75597
This explains a lot, thank you for posting Jeffrey.
I've been having issues with my tank not properly venting. We get a puff of odor outside the boat whenever we flush. I know it needs more airflow, but I wasn't sure how to do it.
The screen on my vent through hull was clogged/rusted/too small, so I replaced it with an open through hull. I had to put a pie plate in the hull liner in order to get the through hull out. It has helped some but not enough.
I thought the vent line ran to the aft end of the tank but could never find it. I now see why.
Eventually I think I'll do the same as you, run a new line. But I have a big trip coming up in a few weeks, without time to make that change, so maybe I'll just replace the filter to get me through this trip. Was the filter obvious?
Thanks,
Doug