[C38] Head direct discharge and holding tank seacocks. Closed or open when sailing?

[Vassili Valayannopoulos]

Hi Douglas,

I checked the vent hose and stanchion with a wire and it goes all the way into the holding tank. Also U don’t quite understand how opening the direct discharge seacock helps take pressure off the holding tank circuit when the Y valve is switched to holding tank.

Thanks!
Vassili



From: Listserve <listserve-bounces at catalina38.org> on behalf of Douglas Allardyce <doug.allardyce at att.net>
Date: Wednesday, July 30, 2025 at 12:00 PM
To: listserve at catalina38.org <listserve at catalina38.org>
Subject: Re: [C38] Head direct discharge and holding tank seacocks. Closed or open when sailing?
Check the vent on the tank
________________________________
From: Listserve <listserve-bounces at catalina38.org> on behalf of Vassili Valayannopoulos <vassilival.boston at gmail.com>
Sent: Sunday, July 27, 2025 4:28 PM
To: listserve at catalina38.org <listserve at catalina38.org>
Subject: [C38] Head direct discharge and holding tank seacocks. Closed or open when sailing?

Hi Folks

The head on my C38 is connected to a holding tank with a macerator pump and its own discharge seacock and I also have a direct discharge hose with its own seacock. I have a Y valve that allows to select one or the other.

When I want to evacuate the bowl into the holding tank I need to have the direct discharge seacock open otherwise I am getting overpressure in the holding tank that prevents me from pumping (even when the holding tank is empty and even when the holding tank’s seacock is open).

I would assume that with the Y valve switched to holding tank and the direct discharge seacock open the risk of seawater back flow is low when underway but would love to hear your thoughts and how you handle this on your boats. It would be annoying to have to open and then close the direct discharge seacock every time someone needs to use the head.

Thanks in advance!
Vassili

Sailing on Naftaki
Winthrop MA
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