F30 Holding Tank Set Up Question

Fresh/Waste Water Systems, Watermakers, HVAC, Refrigeration...
MarcHudgins
Posts: 19
Joined: Sun May 01, 2022 9:26 am

F30 Holding Tank Set Up Question

Post by MarcHudgins »

Hello! New member here and the new owner of a 1987 Mull F30. Apologies in advance for the amount of questions I am likely to be posting as I get to to know the boat.

First up: I seem to have a relatively complex waste management system and I'm trying to sort it out and see if these were stock or if someone got creative.

What makes it complex is that it seems to have a manual pump for dumping the holding tank overboard. I believe the surveyor improperly identified it as a manual bilge pump, but the hoses only run between the holding tank and the overboard seacock. It's located under the v-berth along with the rest of the connections from the toilet. The system seems designed to find as many ways to get effluent overboard as possible, which is not my need given that my primary cruising area is the Chesapeake Bay.

One of the reason I ask is that the pump has come come unattached from the hull (it seems it was glued in place) and I'm trying to figure out if I even want it still.
PXL_20220429_194022749.jpg
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bad
Posts: 184
Joined: Sat Jul 09, 2011 11:14 am

Re: F30 Holding Tank Set Up Question

Post by bad »

If you don't want to empty your holding tank manually overboard, then you don't need the pump. If you can make your boat simpler, that's always a plus.

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newt2u
Posts: 236
Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: F30 Holding Tank Set Up Question

Post by newt2u »

Hi Marc,

You may want to look at the page below for various layouts of heads tank, through hull and deck pump emptying. I had to do some pipe tracing to understand the setup I had on an earlier boat and found this quite useful. As you can see most setups have a valve that diverts waste either into the holding tank or directly to the through hull. Most then have a Y connector taking both the heads output and pumped output from the tank to the through hull. The writing on the Hull seems to say you have a valve (not shown) that selects either from the holding tank or from the heads to your through hull. However I think the label may be misleading and probably selects heads to tank or heads to through hull. Anyway here is the link:

https://www.tek-tanks.com/sanitation-sy ... d-layouts/
Rockin - F21 twin drop keels - located Whitehaven, Cumbria, UK

MarcHudgins
Posts: 19
Joined: Sun May 01, 2022 9:26 am

Re: F30 Holding Tank Set Up Question

Post by MarcHudgins »

Thank you. I've attached some pics wit the rest of the story, though they are hard to assemble into the complete picture. I'll be going down to the boat on Saturday and hope to sort it out better. Meanwhile, I'll check out that reference.
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PXL_20220429_194015513.jpg
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newt2u
Posts: 236
Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: F30 Holding Tank Set Up Question

Post by newt2u »

Yes difficult without seeing more. The second pic seems to be the trough hull for the heads. If that is so the writing next to it does not make much sense. Presumably head OB means the heads goes out directly to this through hull so it should be open. Not sure why you need to close it for tank OB. Unless the holding tank is only emptied through a deck fitting. My best guess is that the Y valve takes the heads and diverts to either tank or through hull and the tank is emptied through a deck fitting. But then you would not need the manual pump, so there is probably more to the picture.
Rockin - F21 twin drop keels - located Whitehaven, Cumbria, UK

MarcHudgins
Posts: 19
Joined: Sun May 01, 2022 9:26 am

Re: F30 Holding Tank Set Up Question

Post by MarcHudgins »

In case anyone is curious, this is my first best guess at tracing the general flow of the system. Essentially it has the standard head to overboard or tank, but is also set up to send the tank overboard via the manual pump in addition to the tank to pump out.
MSD Flow.png
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bad
Posts: 184
Joined: Sat Jul 09, 2011 11:14 am

Re: F30 Holding Tank Set Up Question

Post by bad »

Them a lot of Y valves...🤔

MarcHudgins
Posts: 19
Joined: Sun May 01, 2022 9:26 am

Re: F30 Holding Tank Set Up Question

Post by MarcHudgins »

You read my mind, lol. Something for every occasion. It seems if you randomly dialed each one in you could get into trouble.

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newt2u
Posts: 236
Joined: Wed Sep 11, 2019 11:24 am
Location: UK

Re: F30 Holding Tank Set Up Question

Post by newt2u »

Yes that would work but you have at least one thing missing. The valve on the through hull, without closing that you would get flow to both OB and tank. Also you had another two way valve in one of your pictures (PXL_20220429_194015513.jpg), perhaps that was to stop the pump backfilling the heads, which you would not want!!
Rockin - F21 twin drop keels - located Whitehaven, Cumbria, UK

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RadioZephyr
Posts: 259
Joined: Mon Jun 27, 2016 10:04 am
Location: Boston, MA

Re: F30 Holding Tank Set Up Question

Post by RadioZephyr »

This isn't exactly on topic, but I figured it might be of interest. My boat had an upgraded holding tank setup that added a new 30 gallon tank under the v-berth and reused the original 12 gallon tank to hold "fresh" water to flush the toilet. The problem was, I wanted a way to discharge directly overboard from the head for when I go offshore, instead of relying on the macerator pump to discharge the tank. It took a bit of engineering, but we were able to do it with a minimum of Y valves.

Plumbing system diagram - upgrade 2.0 vs. original.png
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Josh
Sunset Spy
F38, Hull #152
Boston, MA

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