[C320-list] Repurposing head thru hull

[ART HARDEN]

Consider the purpose of a thru hull as to how you can use it. If it is a drain, then then it may not work well for a pickup without a means to isolate the drain. Even a pickup is not the best without an isolation or check valve. How I know this is I plumbed the wash down pump on my Capri 26 to the head pickup. It worked but it worked a lot better once I put a Y valve in. 

If you have a dual hose thru hull maybe re plumb the shower and sink together and change the shower discharge to a wash down pump pickup. I am not sure what the discharge pressure is on the shower line so maybe an isolation on the drain line as well. Maybe something as a simple drain plug will take care of any back-flow. 

This makes me think I may re plumb Tortuga when I add a wash down pump. Keep in mind regarding the above, that where the pump is located makes a big difference. If the pump is below the waterline isolating the pickup may not be as critical. 

Just my thoughts. 

Sent from my iPhone
Art Harden
Catalina 320 "Tortuga" E-62
937.885.9380 (o)
937.477.5544 (m)

> On Feb 4, 2023, at 7:45 PM, Troy Dunn via C320-list <c320-list at lists.catalina320.com> wrote:
> 
> 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