[C320-list] Repurposing head thru hull

[surprise thompson87.com]

I did it differently in part because of concern #3 and in part because I didn't think it was a good idea to have a hose running below the waterline all the way to the bow. I added a thruhull to the port-side compartment in the v-berth and put the pump in the same compartment. This resulted in less complexity and shorter runs for both the plumbing and wiring.

Hose from the pump runs up to a hose bib high in the anchor locker. You only need a siphon break if the run end is potentially below the water line. That's an issue for the head (at least when heeled) and for the shower sump, but not for the top of the anchor locker.

A tip: You probably want higher capacity than you initially think. I wish I had gone bigger.

Scott


-----Original Message-----
From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of Troy Dunn via C320-list
Sent: Saturday, February 4, 2023 7:44 PM
To: C320-List at catalina320.com
Cc: Troy Dunn <troutwarrior at gmail.com>
Subject: [C320-list] Repurposing head thru hull

I'm finally getting around to installing a washdown pump on Wonky Dog.   On
many hulls in the 400-600 range like Wonky Dog there is a single forespar marelon thru hull beneath the head sink that has two barbs.  One of the barbs is connected to the shower sump pump via a anti siphon and check
valve.   The other was originally connected to a anti siphon and then the
head.   We removed the seawater flush when we installed an electric head.
So now I have a "spare" barb.   I want to repurpose this barb to feed a
washdown pump.   I have two questions (well, maybe three).  1) Has anyone
else repurposed one of these inlets? 2) If I’m going to a washdown pump do
I need an antisiphion?  3) how does the two barb thru hull work?!   Why
doesn’t the head suck wind as opposed to lifting water through the seacock, is it because the shower sump pump has enough resistance to not allow air to flow through the pump?  Or is there some other reason I can’t think of and will a 5 gpm pump overcome said resistance and function poorly?

Regards

Troy Dunn
Hull #514