[C320-list] Holding Tank Flooding

[Jeff Hare]

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 <Catalina at thehares.com> 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 
>