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Author Topic: Holding tank repalcement  (Read 1799 times)

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mitch brown

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Holding tank repalcement
« on: July 30, 2001, 09:51:57 AM »

Excuse me if I have already posted this question, but if I did, I don't think I ever received any replies. Everything all at once seems to be going to s--t at the same pun intended. My macerator quit working (keeps blowing fuses), the holding tank hoses are very brittle and calcified (I'm guessing that they are probably severely resricted), and the flappers and valves on the head are shot (everything from the holding tank is flowing back into the head). As you can imagine it wasn't a pleasant experience after 5 days at Catalina Is.!!!
 Here is my question...I want to replace everything from the thruhull to the holding tank (except the toilet, its relatively new). The odor has gotten to be a real problem (even with the holding tank filter). I assume that the waste hose even though it is supposedly impermeable......isn't anymore! Has anyone replaced their holding tank? Should I go with a replacement tank from Catalina if there is one? Is it necessary to cut into the port bench seat to get the tank out or the new one in? And if starting from scratch, do you think a Y valve should be installed to pump straight overboard? It is illegal to do so here in So. Cal, and you are required to have it wired shut, so I'm thinking of doing away with it. Any help would be mostly appreciated. Bu the way, does anyone in So. Cal. know of a pumpout station that is working?!?!??
 Mitch Brown
 #282 Sea Vu Play
 Long Bch CA


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Holding Tank Replacement
« Reply #1 on: July 30, 2001, 11:29:30 AM »

 Remarkable timing for your post.  I boarded my boat on Saturday to find that the holding tank  had backed up into the head, and the odor was less than terrific.  Then when we woke up Sunday AM, there was some disgusting discharge in the bilge.  The only source was flushing the head a couple of times. So here is what I found out:
 When the holding tank is overfilled, the pumpout may not have the oomph to clear the vent line and allow air back in.  The same may be true for the macerator.  The vent line ran athwartships from the vent in the center top of the tank, over the edge of the tank, to the underside of the outboard edge of the opening.  When the tank is full, and bloating just a bit, I noticed the hose is pinched between that cover and the edge / corner of the tank, and that the hose is below the level of the top of the tank for about 2 feet as it runs aft to where it rises to the stanchion seat.  I had tried pumping out last weekend, and thought it seemed like an awful short time to pump an entire tank, and it turns out it was where the pumpout could no longer overcome the vacuum force caused by the plugged vent line.  Now I know better what to look for.
 The water in the bilge was from a different place in the system.  To your point, the rubber hose between the macerator and the thru-hull was actually cracked, and weeping waste water.  It was able to do so because it was actually pressurized, with the tank bloating just a bit, and trying to force the waste out to the closed thru-hull.  The pressure forced it right through the hose walls.  It was also trying to come out of the head (we could hear it "wheezing" like any pressure bottle with a small leak under the cap).
 The first thing I did was clear the vent line by blowing air into the tank, with the deck fitting open, and the pumpout pumping.  I made sure it remained clear, then pumped out and rinsed the holding tank as best I could (both from a hose topsides, and pumping water in from the head).
 I then re-routed the vent line to run from the outboard vertical point to the inboard edge of that opening along the aft edge of the tank, then run forward along the top of the tank inboard.  There was at least 1/2" more room over the tank inboard edge than there was over the outboard edge.  This eliminated the pinch point on the vent line.
 Since the great lakes do not permit macerator use (I don't believe), I disabled it, disconnected it from the tank fitting, cleaned it out, and put a 1 1/2 inch threaded cap into where the macerator used to connect.  If and when I sell the boat, I'll re-install it with a Y-valve that locks (a requirement to lock it out on the inland lakes).
 I looked at the tank, and thought about what I would do if I had to remove it.  My guess is that if you removed the aft end retention (a piece of plywood glassed into place), you could slide the whole tank aft, and it would lift out of the existing opening.  Then upon replacement, just glass in a new piece of plywood.  They sell cutter wheels (small circular saw blades on a shaft) that can go into a drill to cut away at the edges of that plywood.  Safety glasses and a dust mask are a must!  The macerator and plumbing would have to be off, but that's a necessity if your replacing it anyhow.
 Sorry it's so long winded, but that is my s--tty story. I can definitely sympathize with you!


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Everything about sanitation and then some
« Reply #2 on: July 30, 2001, 02:16:56 PM »

Check out this website.  Go to the page from Peggie Hall (Head Mistress).  She is an expert in MSD's.  Extremely helpful information.
Roc - "Sea Life" 2000 MKII #1477.  Rock Hall, MD
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