Adding a head macerator pump––need vented loop, or is valve OK?

[OpenRange2025]

Hi all! Lauren here––new Beneteau owner. I'm prepping my 1990 Beneteau M500 for a Pacific crossing. I want to add a macerator pump and plumb a holding tank to dump overboard, but want to make sure I don't sink the boat when I do it!

The old owners (who circumnavigated) removed all but one head holding tank. However, the holding tank's only discharge is to a waste pump-out plate on deck. When offshore at a legal distance, we would like to be able to dump our tank straight overboard so we are not tethered to places with pump-out services. Therefore, I'm looking into adding a macerator pump and wye-ing it into our existing thru hull. That said, the thru hull is below waterline, and the tank is at roughly the same level, perhaps slightly higher, so I want to be careful about siphoning/backfilling the tank.

I think my plan may best be understood with diagrams. I've attached a diagram of the current setup and a diagram of my proposed setup (new additions in green).

I have 2 main questions to make sure I don't sink!
1. I have read @Peggie Hall HeadMistress previous threads on adding vented loops to these tank dumping systems to prevent ocean water siphoning back into the tank. Can I replace a vented loop with redundant diverter valves that will remain closed at all times unless actively dumping out the tank? The tank is vented, but there are currently no vents in the hoses.

2. I currently plan to put an open Y connector at the tank discharge fitting (with a few inches of hose on either side––no hard on hard!). However, I'm wondering if this needs to be a valve instead of an open connector so that the macerator pump duckbill valves, etc don't get suctioned and inverted with tank pressure or pump-out suction. Are the pumps able to withstand that suction, or do I need valves to close off the pump on both sides?

Final question... the current hoses are all black corrugated sanitation hoses. What are the best connectors to cut and re-connect these to valves, etc? I worry that hose clamps might not get a good seal given the corrugated bumps. Links to buy connectors appreciated!!!

THANK YOU ALL!! Any help appreciated!

- Lauren

 

[JoeWhite]

Here is my setup

Macerator Pump | Sail La Vie

mei1970.org

The installation is much simpler. The Y valve goes on the output of the holding tank. From Y valve one hose goes to pumpout and one goes to macerator. After macerator hose it goes to a throuhull valve. No siphoned loop is needed.
See my link above and view the album photo.
Use Grocco bronze Y valve. Use plastic 1 1/2" sanitation hose. There is no permiation of unwanted odor. Use hair dryer to soften the hose to form the curves.

 

[Peggie Hall HeadMistress]

An alternative suggestion: Put a y-valve in the head discharge line that creates a choice between pumping into the tank or overboard. You'll prob'ly have to come in for water and/or provisions at least once, most likely Hawaii, maybe Easter Island too, depending on where you depart...those should be the only times you'll have to pump into the tank..Pump out and rinse out the tank last thing before leaving each time...switch to direct discharge as soon as you're in open ocean again. You'll need a vented loop in that line, but you eliminate the need for a macerator pump that's sure to fail at the worst possible time, leaving you with a full tank without any way to empty it. However vented loops do NOT replace the need to keep below-waterline thru-hulls CLOSED except when in use...y-valves are not an acceptable alternative.

--Peggie

 

[Ralph Johnstone]

I think you'll find @Peggie Hall HeadMistress 's suggestions are about the best you'll get anywhere.

However, I did happen to notice this one item :

What are the best connectors to cut and re-connect these to valves, etc?

Can't say I've ever seen a sanitation hose of any repute which looks similar to your hoses :

The one unacceptable flaw I see is that the hose requires a rubber coupling to fit it on to a barbed adapter, either plastic or metal. The rubber coupling requires that the hose be screwed into it which is a leak waiting to happen given sufficient time. Also a little nerve wracking if the thru hull is accidentally left open when the boat is closed up. The correct connection to a barbed tank fitting or valve would be as shown below :

Large dia. fittings, small fittings, the hose is clamped OVER the barbed fitting thereby ensuring no leaks. The vent line has only one gear clamp due to a stubby barbed adapter. I'm scheduled to change it "someday."

Larger hoses require both heat from a hair dryer and a non-petroleum grease to install the hoses and ensure they come off again, years down the road. As far as the hose slipping off because of the grease in the joint, get a small party together to try it once the gear clamps are on. Any means, any tools.

 

[Peggie Hall HeadMistress]

The industry has always recommended dish washing liquid to lubricate hose connections...I've always recommended K-Y because it's a water soluble surgical jelly that's a lot slicker than dish washing soap, making it lot easier to install and remove hose from fittings, and readily available from any drugstore.

-Peggie

 

[Peggie Hall HeadMistress]

Can't say I've ever seen a sanitation hose of any repute which looks similar to your hoses :

That's because they're corrugated hose using rubber cuffs, which haven't been used in sanitation systems for at least 40 years. The first sanitation hose--flexible PVC # 148-- was introduced in the mid '80s...the ONLY specifically "sanitation" hose until the early-mid '90s when Trident introduced their double walled rubber 101--the first hose to have warranty (5 yrs) against odor permeation...SeaLand Technology soon followed with their more flexible "OdorSafe" hose. Ronco Plastics was still selling corrugated hose when I became a distributor for them in the late '80s. I'd already become a distributor for Trident and was selling their flex PVC. It was an interesting time to be the only company to specializ exclusively in marine sanitation--the least "glamorous" part of the boating biz, I had -0- competition for the first few years! Surprisingly the the only sexist comment I ever got was from another woman...I'd just conducted a seminar at a boat show and a couple followed me back to booth...the wife greeted with, " the whole time you were talking I couldn't help wondering why an attractive women would choose to be in your field!" My reply: "Cuz it's fun, profitable, and a great way to meet a lot of men!"

(Here ends my late night rambling)

--Peggie

 

[sailme88]

Personally I'd got with a MSD... That aside, prepare for the worst. In the worst... the macerator fails. Our macerator is isolated. Directly out of the tank is a sewage rated gate valve. Next is a sewage rated union and then the macerator. From the out flow of the valve to the macerator there is about a pint and a half of black water. If I need to swap out, a disposable aluminum foil casserole pan will easily fit and capture everything but the odors..

 

[jssailem]

2. I currently plan to put an open Y connector at the tank discharge fitting (with a few inches of hose on either side––no hard on hard!). However, I'm wondering if this needs to be a valve instead of an open connector so that the macerator pump duckbill valves, etc don't get suctioned and inverted with tank pressure or pump-out suction. Are the pumps able to withstand that suction, or do I need valves to close off the pump on both sides?

When you are beyond the 12 mile limit, the pumping of effluent overboard is less than a pod of dolphins swimming by, leave in their wake.

It seems more simplistic to me (fewer hoses) to have all black water pumped into the holding tank. That way, no one forgets to close the dump overboard hose. I think a diaphragm pump provides more system longevity than a macerator pump. I found the Whale Gulper TP MK2 to be a work horse.
Whale says:

NON CLOG, NO FILTER WASTE PUMP BUILT ON MORE THAN TWO DECADES OF MARKET LEADING PUMP TECHNOLOGY. PUMPS UNMACERATED TOILET WASTE.​

It is an open-water option that is not used in inland waters. The hose system and pump can be flushed clean and shut when not in use. With a solid, well-maintained through hull and Y Valve, you have a controlled system in all waters.

 

[Ralph Johnstone]

That's because they're corrugated hose using rubber cuffs, which haven't been used in sanitation systems for at least 40 years.

That fits as the boat's a 1990 model. I guess the corrugations presented too much of an irregular surface to allow for slipping the hose OVER the barb and still expect to get a good seal, hence the idea of screwing the hose INSIDE the cuff provided a better seal .................... until it didn't.

The ABYC puts out all sorts of recommendations for thru-hulls such as :

- double clamping hoses
- corrosion resistant thru-hulls
- metal fittings to thru-hull be able to withstand given moments of torque without failing
- and other such safeguards

But when it comes to screwing a corrugated hose into a rubber cuff at a thru-hull "Meh, it'll be fine."

 

[NYSail]

I have. 423. Got rid of all mascerater pumps and plumed the holding tanks to gravity discharge. Nothing to go wrong. Open through hull and away it goes. It’s a nice attribute. Less valves, less hoses, less to break.

any questions let me know

good luck!
Greg

s/v Souleil

 

[OpenRange2025]

An alternative suggestion: Put a y-valve in the head discharge line that creates a choice between pumping into the tank or overboard. You'll prob'ly have to come in for water and/or provisions at least once, most likely Hawaii, maybe Easter Island too, depending on where you depart...those should be the only times you'll have to pump into the tank..Pump out and rinse out the tank last thing before leaving each time...switch to direct discharge as soon as you're in open ocean again. You'll need a vented loop in that line, but you eliminate the need for a macerator pump that's sure to fail at the worst possible time, leaving you with a full tank without any way to empty it. However vented loops do NOT replace the need to keep below-waterline thru-hulls CLOSED except when in use...y-valves are not an acceptable alternative.
--Peggie

Thanks @Peggie Hall HeadMistress ! Confirming that even if we keep the thru hull shut, and have a closed Y-valve that shuts off the thru hull to the tank discharge hose, and have second closed Y-valve at the tank discharge fitting, we still need a vented loop?

Assuming we do, can the loop go downstream of the macerator pump (between the pump and the thru hull)? I've seen from your other posts that the height should be 6-10" above waterline at any angle of heel. Diagram attached of proposed location of vented loop in the system. I think the only problem might be whether or not the macerator pump can pump uphill several feet. It seems that many top out at 4'.

Is a product like this appropriate for the vented loop?

Thanks for your expertise!
- Lauren

 

[OpenRange2025]

I have. 423. Got rid of all mascerater pumps and plumed the holding tanks to gravity discharge. Nothing to go wrong. Open through hull and away it goes. It’s a nice attribute. Less valves, less hoses, less to break.

any questions let me know

good luck!
Greg

s/v Souleil

Thanks Greg! Love the simplicity here. Is your thru hull below the waterline? And is your tank significantly higher than the thru hull? My tank is roughly at the waterline, so I'd worry about backpressure from the thru hull sending water back up into the tank.

 

[OpenRange2025]

That fits as the boat's a 1990 model. I guess the corrugations presented too much of an irregular surface to allow for slipping the hose OVER the barb and still expect to get a good seal, hence the idea of screwing the hose INSIDE the cuff provided a better seal .................... until it didn't.

The ABYC puts out all sorts of recommendations for thru-hulls such as :

- double clamping hoses
- corrosion resistant thru-hulls
- metal fittings to thru-hull be able to withstand given moments of torque without failing
- and other such safeguards

But when it comes to screwing a corrugated hose into a rubber cuff at a thru-hull "Meh, it'll be fine."

This all makes sense... I was absolutely scouring the internet for any intel on these hoses, but given that they are out of date and out of regulation it makes sense that I couldn't find anything! I think when doing this project, it definitely would be prudent to replace the overboard hose (which, to your point, appears to be leaking) with proper marine sanitation hose and double hose clamps. Bummer, as I have a ton of leftover corrugated hose from other areas in the boat, but won't be too expensive I think!

Do you have a brand of hose you like that allows for a lot of sharp bends? It's cramped down there!

 

[Ralph Johnstone]

Do you have a brand of hose you like that allows for a lot of sharp bends? It's cramped down there!

I was advised by @Peggie Hall HeadMistress a while back, in no uncertain terms, that Raritan Saniflex hose is
the only hose to use in tight spaces :

Hose cuffs: question for H31 ownwers.

The cockpit drains, galley sink drain, head sink drain and anchor locker drain all use hose cuffs with spiral wire hose on my boat. Are these fittings original? Does your H31 use them? The guy at West Marine said the use of hose cuffs is to be discouraged because they aren't marine grade...

forums.sailboatowners.com

See post #9.

I had recently installed all new Trident Premium Sanitation hose when exchanging my Jabsco head for a new Raritan PH Superflush head. I found that this afforded one of the best workouts I'd had in a long time and yet mine was a pretty straight run to the holding tank. Peggie tells me she had been preaching the advantages of Saniflex hose for years prior to my doing my job but it just hadn't registered on me. Both hoses carry a 10 yr. guarantee against odour permeation, if I'm not mistaken. The only decision here is a broken bank account or a broken back. Money can be replaced, your back ........... maybe not so much. Trust me, go with the Saniflex. You won't even remember how much it cost a week after it's installed.

 

[Ralph Johnstone]

The only decision here is a broken bank account or a broken back.

Bit of an update here. I was curious as to HOW much more Raritan is compared to back in the day when I ran a comparison. Either Trident has increased their price for 1-1/2" hose or Raritan has very significantly dropped theirs :

Use the very best and save yourself $1.03 if going through Defender.

 

[jssailem]

I sourced Fisheries Supply June 2024
Of course, that is USD. For qualifying orders Over $99 they ship free.

RARITAN
1-1/2" Sani-Flex Sanitation Hose -Per foot
SKU: 390090
Item ID: RAR SFH
Per ft or 50ft
$16.80
Qty: 15
$252.00