Thoughts on replacing 1-1/2-inch hose with 1-inch hose

Aug 4, 2021
12
Hunter 38 Solomons
2009 Hunter 38, original configuration: The hose coming out of the head (toilet) is 1", makes an odor-trapping loop and runs through a bulkhead where it is coupled to a 1-1/2" hose that runs maybe 9 or 10 feet to the holding tank. The head has an electric macerator the grinds everything (noisily) into mush. Why bother with the 1-1/2" hose? Why not run 1" hose the entire length to the holding tank? I am not trying to be cheap where it counts, but aside from the extra $100 to run the 1-1/2" hose, that hose is going to be holding more of what I do not want stinking up the aft berth. Granted, the new hose will not be permeated for years to come, but still, is there a reason to go from 1" to 1-1/2"? For a more complete scenario (see graphic): The hose running from the tank to the thru-hull (for dumping at sea where allowed) is 1-1/2" for ~10 feet to a second macerator pump, the output of which is a 1" hose. I could see the sludge coagulating at the bottom of the holding tank so can understand the 1-1/2" between there and the 2nd macerator pump. I will note that I plan to make a significant change from the original configuration: the shut-off valve that rarely (if ever) that is to be opened for external dumping will be relocated to the output of the tank at the tank instead of 8-10 feet away at the (2nd) macerator pump--full of sludge. (What kind of logic was that?)
H38TailWindSanitationHoseReplacementPlan.jpg
 
Jan 19, 2010
12,553
Hobie 16 & Rhodes 22 Skeeter Charleston
Makes sense to me but... I don't have much experience with mercerator pumps.
 

jviss

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Feb 5, 2004
7,089
Tartan 3800 20 Westport, MA
I'm by no means an expert on this, but here's my thought, anyway.

First, there was probably a reason they did things originally as they did. For example, why an adapter to go from 1" to 1 1/2"? Well, it could be because they needed the lower resistance of a 1 1/2" hose for most of that run, and 1" worked better for the short piece in the head. About relocating the valve on the output side - I'd do some research before I'd move that, too.
 
Dec 2, 1997
8,924
- - LIttle Rock
Contrary to popular opinion among the over-analytical crowd, there really no real reason to use 1" sanitation hose...there should never be any waste or sludge left sitting in it if it's plumbed correctly and if there is, a cupful can generate just as much odor as a gallon. Your toilet has a 1" hose coming out of it because that 's always been Jabsco's standard size for it...every other toilet mfr has always used 1.5". There's 1"-1.5" reducing adapter in your installation because the standard size for holding tank inlet and discharge fittings is 1.5". Deck pumpout fittings also need 1.5" hose. Macerator pumps have 1.5" inlets and 1" outlets. However if your home port of Solomons is Solomons MD, you won't need a macerator pump because it's illegal to dump a tank in the Chesapeake Bay

Most toilet mfrs now offer a toilet discharge fitting that can use either a 1" or 1.5" discharge fitting, which would allow you to use 1.5" hose without the need for a reducing adapter to connect it to the holding tank.

Raritan SaniFlex is the top-rated sanitation hose. RaritanSaniFlex hose Not only has it proven to be 100% odor permeation resistant (even has a 10 year warranty against it), but it's also so flexible it can be bent almost as tight as a hairpin without kinking, which makes most re-hosing jobs a LOT easier. Defender has it in both 1" and 1.5" for the lowest price and sells it by the foot, so you only have to buy the amount you need.

I'll be glad to help you sort out how to do this job right the first time, but first I need the answers to a couple of questions: Your tank appears to be long way from your toilet...how long is your toilet discharge line? What's the make/model/approx age of your toilet? I'm concerned about its ability to move flushes all the way into the tank without a lot of help from gravity (which is achievable). And why does there appear to be 360 degree loop in the 1" hose coming out of your toilet?

--Peggie
 
Aug 4, 2021
12
Hunter 38 Solomons
Peggie,

Thanks for the reply.

Count me as one of the analytical types. Just because “they have always done it that way” does not work for me. I subscribe to the “Five-whys” philosophy; short version: why have they always done it that way?

In this case, one wonders if 1-1/2” hose has always been used by the company to which you sold your business because that is what manual flush toilets needed to effectively move solid waste. Could it be that JABSCO uses 1” hose because their electric macerating toilets and self-priming waste pumps reduce the solid waste to sludge with sufficient viscosity and push it with enough pressure to move it through a 1” hose up the 3 or 4 feet to the top of the holding tank? I think so but was hoping for an expert’s assessment.

To answer your questions took another trip to the boat …

Based on the drawings in your The New! Get Rid of Boat Odors book, I have a JABSCO 37045 QuietFlush. It is original equipment on the 2009 Hunter 38. Fortunately for me, when we purchased the boat in October 2020, the boat had hardly been used (original plastic wrap on the range, 110 hours on the engine, for example). The toilet works quiet well, drawing water from the onboard freshwater tank, or when docked from the marina’s freshwater line (filtered).

The entire existing hose line length, including the loop in the 1” hose at the toilet (ref page 50 of your The New! Get Rid of Boat Odors book), is approximately 15 feet, erring on the high side. The base of the toilet is approximately 15-inches below the base of the holding tank, and approximately 4-feet below the top of the holding tank where the hose from the toilet enters.

The loop in the 1” hose does not, as your book indicates, rise to a level above the input to the holding tank. I will correct that situation when I replace the hose by running it as high as I can get it then back down to the tank. As “… so flexible it can be bent almost as tight as a hairpin without kinking” translates to 3.2” radius for the Raritan SaniFlex Odor Shield hose; a factor in putting that loop in a tight space (~10 inches of space needed for a 180-degree bend).

Regarding your comment that there should not be any sludge in the hose if the toilet is flushed properly – I wholeheartedly agree, with one exception. The Hunter manual states (for electric macerating toilets), “… a minimum of 1 gallon to rinse urine completely out of the machinery, a minimum of 3 gallons [to] clear solids and paper. Insufficient flushing shortens the life of the motor and macerator.”

The exception, based on the original configuration with the plumbing, had the valve for the overboard discharge at the macerator pump (~9’ of 1-1/2” hose). The first tank full of waste (perhaps in 2010), had the solids settle in that 1-1/2” overboard waste hose, which had never gone overboard due to the regulations on dumping. That waste broke down over time but sat there for perhaps 9 or 10 years. That was beyond the permeation limit of the original hose – and was just the job you might imagine when I removed that hose last fall and closed off the holding tank where I am showing the new valve location in my updated diagram. I will be putting in that valve, 1-1/2” hose, and macerator as the boat, though based where no dumping is allowed, will find its way to the Atlantic Ocean and may need overboard dumping (where allowed).

As an analytical type, I calculated the volume of water/sludge in 10 feet of 1” and 1-1/2” hose; more than twice the volume in 1-1/2” hose (0.41 gal vs 0.92 gal). Calculating the flow resistance between the two diameters can get quite involved, especially since I do not know the viscosity of the sludge coming out of the macerating toilet.

Again, thanks for your assistance.
 

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