Installing macerator pump out

[Blair Clark]

Hi there,

I may have been mentioned before, but we are planning to do longer cruises and thinking more on creature comforts that will make extended cruises more enjoyable. two systems that I am thinking of installing are 1) replacing one water tank with a water maker and using the space for additional storage and the water maker and the second project is to install a macerator to be able to discharge the holding tank overboard When permitted .

 please offer comments on how to best design the placement of the macerator in our boats. 34+ my holding tank is starboard side between vanity and shower but I have full access to the compartment after having custom work. Currently, my sewage leaves The toilet goes to a Y valve that I can discharge to a seacock or route to a holding tank currently the holding tank only has a pump out hose and a vent hose. Any thoughts will be appreciated including best watermark and best macerator and touting of sewage lines.

Thanks 

Blair

[Tom S]

Hi Blair, Here are my thoughts.  Our 34+ is new to us but on my previous boat I installed a composting toilet and at the first hint of trouble with the head, tank or hoses on Corsair I will remove it all and install a composting unit. Being on the Great Lakes myself I don't think it's a sin to dump the liquids overboard if you are out in the middle of the lake but in a harbour I walk it to the facilities and in the an anchorage I'd row it ashore, just like all the folks rowing their dogs ashore for the same purpose.  The simplicity and lack of odour are the deal makers for me.  Here's a link to Practical Sailors view and while I don't disagree with what he says the negatives aren't the deal breakers for me that they are for him.

https://www.youtube.com/watch?v=dBJ1DHITFpI

Cheers,

Tom S

[Cesar Vallejos]

Hi Blair,

My holding tank is under the sink and routes its discharge in two directions:

1.Upwards to the pump-out thru-deck

2. Aft into the cockpit lazarette, where the macerator pump resides almost all the way back in the lazarette. Beyond the macerator pump is a vented loop and the thru-hull for discharge in open waters.

Obviously you would need new exit from the holding tank.

[shawmacs]

Our 34+ has a Y valve in the exit of the holding tank. One to deck pump out, and one to the macerator pump. The macerator pump is mounted in the starboard lazarette. The hose to the macerator is routed under the shower seat.
I suppose if someone wanted to open up the shower seat and put a hatch in, the macerator might fit under there. As I start digging into the vessel more, I'll have to investigate that. 

Scott

S/V Pacific High

[Harvey Hauschildt]

There are portable water makers that are about the size of a Yamaha 2000. They are easy to store and would allow you to keep both tanks. I explored this option once but for Northwest cruising it would just be another accessory I don’t really need. 

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On Nov 17, 2025, at 4:25 PM, 'shawmacs' via C&C 34/36 Owners <cc-...@googlegroups.com> wrote:

Our 34+ has a Y valve in the exit of the holding tank. One to deck pump out, and one to the macerator pump. The macerator pump is mounted in the starboard lazarette. The hose to the macerator is routed under the shower seat.

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[Chuck Scheaffer]

Harvey, you are making potable water while the others are pumping black water.  Not sure I understand your reference.

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[Francois Rivard]

Composting heads might be fine in colder climes but are breeding grounds for little decomposer flies where it's hot if you're not 100% on top of it 100% of the time. 

One of my liveaboard friends here in GA had one for about 6 months then took it out.  He just couldn't get rid of the flies without getting rid of the toilet...

-François 

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[Chuck Scheaffer]

I hope this isn't too much.  

I will share that I used a bucket pretending I was camping, or sailing in the Vendee Globe during a weeklong cruise.  If you watch the Vendee Globe racers, they always have a bucket lashed bouncing around outside on deck.  Not sure how they handled it when they had mixed crews onboard.  I found two to three inches of water in the bottom was needed before using the bucket.  It prevents things sticking onto the bucket surface.  I was solo and the only boat anchored out in October and the bucket went over the side in a respectful way, so as not to spoil the view from shoreside residences.   I kept the paper separate and put that into a paper towel, and into a ziplock bag and into my trash which was kept till I found a fuel dock or marina.   No smell, very little fuss, and I feel I respected the environment by not discharging any paper.  The paper can be challenging.

C

C

   

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[Blair Clark]

Thanks for the input.

As with many tools they have there application strengths and owner preference. For my purposes at least for now I will not explore the compost option further and am trying to plan a macerator route.

Does anyone know if I can rig a Y valve using the hose that goes to shore suction and a route to use the current hose that goes to seacock. Perhaps that would be too complicated and I will have to install another seacock and through hull.

Thoughts will be appreciated 

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[jsey...@appliedmechanics.net]

Blair,

I installed a macerator a few years ago exactly as you’re contemplating - and it was well worth it.

I really wanted to plumb the hoses as you’re asking – somehow use the existing shore suction hose rather than cut a hole in the holding tank or need another through hull. etc.

 

I was concerned the macerator could provide enough vacuum to lift the waste that high, so ended up cutting a hole in the holding tank as low as I could and installed the macerator under the shower seat, with access provided by a rectangular deck hatch I installed in the seat like a few others here have done.  I was able to tee this into the existing adjacent waste seacock hose (but added a shut off valve), so at least avoided having to drill another through hull. It’s a bit tight in there, but can be done.

 

It's been a great addition, especially when doing extended cruising.  I no longer stress out about having a full holding tank and figuring out how I’ll get it pumped.  Fortunately we frequently sail well offshore, and when we do,  we empty the tank.

 

-John

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