[C320-list] Holding Tank Flooding

[sailor3952 at charter.net]

	Thanks Jeff and others for your informative wisdom. I will simply
keep the thruhull for the macerator CLOSED. End of problem. Your
comments and advise have been most helpful. This group is awesome!
Wish all of you were in the same marina! Thanks

	Kaare & Mary

	-----------------------------------------From: "Jeff Hare" 
To: 
Cc: 
Sent: Tue, 19 Jul 2016 21:11:04 -0400
Subject: Re: [C320-list] Holding Tank Flooding

 Nope I don't believe so. That anti-siphon is only for the head hoses
that
 come from the thru-hull under the sink. There's no anti-siphon
between the
 macerator pump and the holding tank. There's no check valve either,
it's
 only the macerator pump impeller that slows the water into the
holding tank
 unless the macerator pump happens to be above the water line, don't
know for
 sure.

 -Jeff

 -----Original Message-----
 From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On
Behalf
 Of jbrown5093 at yahoo.com
 Sent: Tuesday, July 19, 2016 8:45 PM
 To: C320-List at Catalina320.com
 Subject: Re: [C320-list] Holding Tank Flooding

 Wouldn't the anti siphon loop in the head cabinet prevent siphoning
in
 either directions?

 Jim Brown

 Sent from my iPad

 > On Jul 19, 2016, at 6:26 PM, Jeff Hare  wrote:
 > 
 > I would not be surprised if you could sink your boat this way
depending on
 how the hose leading from the head to the tank is routed and how good
your
 head's duckbill is. If you pump out with the macerator thru-hull open
and
 the head vent is at all clogged, the vacuum will pull seawater in
through
 the macerator pump and water out of the head and could set up a
siphon and
 will likely slowly fill your tank to the water line. I presume but
don't
 know whether the rim of the head is above the water line. If not, the
boat
 can be sunk this way.
 > 
 > Bottom line is that the macerator line does not have a vacuum
breaker in
 it, so it can never be left open. When your tank is being pumped out
 through the deck fitting, I believe you always want that valve closed
 anyway.
 > 
 > -Jeff
 > 
 > -----Original Message-----
 > From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On
Behalf
 Of Kaare Wold
 > Sent: Tuesday, July 19, 2016 4:25 PM
 > To: C320-List at Catalina320.com
 > Subject: [C320-list] Holding Tank Flooding
 > 
 > Skippers, Recently we noticed that our holding tank fills with
water when
 at rest at the dock. At first, thought our dock attendants failed to
pump
 out. We have an AccuGage digital monitor on all tanks. Love that
setup! 
 > We had the tank pumped, while we were present, and as the tank was
being
 pumped out, I could see the AccuGage digital level drop from 3/4 to
1/2 down
 to empty. A couple days later, it was back to 3/4 full without any
personal
 use whatsoever. The macerator thruhull had been open all the time,
although
 we never use that device. All thruhull are opened for winter layup
and I
 never closed it after spring launch. I now closed the thruhull, had
the
 tank pumped out again and.....bingo..., the tank remained empty. Any
ideas

 > from our knowledgeable group??? Could there be a check valve in the

 > macerator pump that is leaking? Looking for some suggestions or
 comments 
 > from someone that may have experienced the same problem. Thanks to
all
 for your comments.
 > Kaare & Mary Wold
 > Sheet Music, #945 Sturgeon Bay, WI 
 >