Upgrading to an Electric Toilet

Kristin and I have a lot of fun taking guests aboard our boat, some of which have never been on a cruising sailboat before. We not only go daysailing with guests, but many times invite guests over to watch fireworks downtown (a nearly weekly occurrence in Milwaukee summers!) while anchored in the harbor. At some point, nature calls, and involves a discussion of how to flush the toilet.

Manual flush toilets on boats really are pretty simple to operate, but they do flush quite differently from toilets in a house. Explaining their operation takes some time, and after a few drinks seems overly complicated. Invariably, either waste doesn’t get flushed, the holding tank fills too quickly, or guests don’t feel comfortable on the boat.

There are other issues with manual boat toilets. It’s hard to control how much water ends up in the holding tank, especially when attempting to prefill the bowl prior to use… definitely an issue with Priorities having small holding tanks in a No Discharge Zone. I find the “glug glug” sound they make is kinda bothersome, too, especially at two in the morning when everyone else is trying to sleep.

A few years ago, Kristin and I chartered a boat in the BVIs with electric toilets in each head. Operation was so simple: one button for water in, one button for waste out, another button for both at the same time. We had lots of control over how much water we used, and therefore how fast the holding tanks filled. Kristin was strongly in favor of Priorities getting an upgrade.


Choosing an Electric Toilet

There are quite a few electric toilets on the market, though many seem oriented towards boats with large heads. Reading the reviews in Practical Sailor got me thinking about the Raritan Marine Elegance, but after sitting on a cardboard mockup seat in the small aft head of our Catalina 400 (visualize that for a second!) I decided we needed to stick with the “compact” bowl size. Our charter boat used Jabsco toilets, which worked great, too, but I liked Raritan’s “Smart Toilet Control” automated flushing features.

I decided to get a Raritan SeaEra QC Electric toilet. There are several variants of these, too… we wanted the most control of water going in and out of the bowl, as well as simple operation for landlubber guests, so I got the Remote Pump with Smart Toilet Control (STC) version. In order to have intake water and waste water have separate controls, there have to be separate pumps for each function… hence a “remote pump.” The STC is merely a fancy control panel and control box with some automated flushing functions… making flushing a simple one button process for guests.

Raritan also has yet another fancy option for flushing with either seawater or freshwater. Many head odors come from microscopic sea life in salty seawater used to flush that subsequently dies in the bowl. Selecting a fresh water flush, especially at the end of the day, can reduce odors if the boat is kept in salt water. The Great Lakes are freshwater lakes, so when we flush with seawater, odors aren’t nearly as much of a problem as on salt water boats.

However, we’re still holding out hope we’ll take Priorities to salt water some day. The Sea-Fresh option also uses a relay to power the remote pump, allowing me to get away with slightly easier-to-install wires (more on this later). I also didn’t need (and haven’t needed) to install all of the “Sea-Fresh” components for our system to work properly while still on the Great Lakes. Though it’s a fairly frivolous add on for us right now, I bought the Sea-Fresh option, too.


Initial Installation Considerations

I probably spent way more time planning the install than I spent actually doing it. It’s challenging figuring out where new hoses will go through bulkheads and around other hidden structural components.

Profile view of toilet base showing close alignment with discharge hose
The discharge hose lined up just right with the new Raritan QC Electric Toilet

The toilet component, which includes the bowl and the waste pump, was nearly the same size as the manual Jabsco Twist & Lock toilet that it replaced. Two of the four mounting bolts were in the same positions, requiring me to only redrill two new mounting holes. The waste pump, normally mounted on the back of the toilet, can be oriented to either side if necessary. I found its standard orientation in back to be the best for our head. The discharge hose, with a mere six inches to work with before it disappeared into the fiberglass under the sink, lined up just right in this orientation.

Base of toilet showing waste pump, remote pump intake, and unused freshwater solenoid
Only two of four mounting holes needed filling and redrilling in a new location when converting from the old Jabsco Twist & Lock manual toilet to the new Raritan SeaEra QC electric toilet

The STC Control Panel containing the flush buttons needed a flat mounting surface with a few inches of space behind it for the telephone-plug-style cable.

Control panel with buttons for "Water Saver," "Normal Flush," "Water Only," and "Empty Only"
Separate controls for filling, emptying, and automated flush functions are what I like about Raritan’s Smart Toilet Control

I wanted it to be in a spot that seemed like a natural location for toilet controls, but not subject to getting bumped when using the head in rough seas. I also needed to be able to fish the data cable from the STC Control Panel to the STC Control Box easily. I settled on a spot just below and to the side of the sink, which is a pretty thin fiberglass panel that is sorta accessible from the access doors under the sink.

Installed electric toilet and control panel
Control buttons were mounted in an obvious, but bump resistant area near the toilet. Catalina 400 owners note: Priorities is a Catalina 400 Mark I, where the aft head does NOT have a divided shower compartment… so my sink and countertop area doesn’t look anything like the aft head in the Mark IIs
Toilet control box mounted in undersink cabinet
The STC Control Box mounted in undersink cabinet. Wire runs go up behind sink and cabinets.

The STC Control Box needed to be centrally located, since all wiring passed through it, but preferably dry and out of sight.

I used up some space in the tiny cabinet under the sink for its placement.

Though at first glance it looks like a very isolated location, the undersink cabinet is open upward to the space behind the sink and countertop, making wire runs pretty easy.


Plumbing a New Intake Hose and Remote Pump

I spent the most time planning and doing the installation of the intake hose and remote pump. Based on the installation instructions and an email discussion with Raritan customer support, I wanted to keep the remote pump away from sleeping quarters to reduce noise. Since I’m probably the guy who would be repairing this pump in the future, I wanted it to be in a serviceable location, too.

I also chose to mount the pump below the waterline, partly so it would stay primed. Though the remote pump is self priming, I was concerned the change in pump noise would be annoying while it “re-primed” during most flushes. However, there’s a risk to having the pump below the waterline… any pump leaks could sink the boat! A below the waterline location also ended up being more convenient than just about anywhere above the waterline, so that’s where I installed it.

Whenever the toilet bowl on a boat is below the waterline, the boat can flood and sink if the thru hull is left open. Even if the intake hose is routed above the waterline on its way to the bowl, seawater can still siphon into the bowl to flood the boat. On my Catalina 400 Mark I, the bowl can occasionally end up below the waterline during more extreme angles of heel, posing a flooding hazard while underway on a starboard tack. Later model 400s have a vented loop installed between the manual pump and the bowl to alleviate this chance of siphoning and flooding. Back when my boat was made, Catalina didn’t bother plumbing a vented loop and merely buried a warning in the owner’s manual to “Close all thru hulls when underway.” I never bothered to close this particular thru hull when underway, and I never had any flooding issues… but I really didn’t want to worry about this ever occurring in the future.

To prevent flooding, I needed to install a vented loop. When installed above the heeled waterline, the vented loop breaks the siphon, preventing the flooding risk. For the remote pump to have proper suction, the vented loop also needed to be installed downstream of the pump.

The original intake hose for the aft head was routed from a thru hull next to the engine intake thru hull. It was a short hose, passing up through the fiberglass platform (and floor) the manual toilet was mounted to. It went straight up from the floor to the intake side of the manual pump of the toilet… nowhere near the heeled waterline.

Weighing the needs of serviceability, the pump noise, the needed vented loop position, the existing thru hull, and the toilet location, I chose to install the remote pump next to the potable water pump under the cabin sole by the nav table. This would result in a long intake hose, but otherwise fit my requirements. The new vented loop was mounted next to the vented loop for the discharge hose in the aft head hanging locker. Miraculously, I was able to run the new hose between all three components, and learned a lot about what was behind the interior panels in that part of the boat!

View of pumps under cabin sole
The remote intake pump was installed under the sole under the nav station, next to the pressure water system pump.
Back of aft head hanging locker showing vented loops for new toilet intake, old toilet discharge, and old discharge Y-valve. Also shows blue wire to remote intake pump control relay.
Located in the back of the aft head’s hanging locker, the new intake vented loop is above the heeled waterline
View under cabin sole showing space where intake hose from thru hull to remote pump was installed
Looking aft under the cabin sole from the nav station. I routed the intake hose in the 3” gap from the thru hull to the new pump location under the nav station. The stringer in the middle generally runs parallel to the sides and doors of the head. The shower sump is visible on the right.



One reason I chose to make the aft head electric rather than the forward head was the aft head’s proximity to the boat’s electrical distribution panel. This meant comparatively short wire runs, allowing for smaller diameter wire that is cheaper and easier to work with.

Additionally, since I chose to buy the “Sea-Fresh” option, the remote intake pump was controlled by a relay rather than being directly wired into the toilet’s STC Control Box.

Small electrical relay box for remote pump
The Remote Intake Pump is switched by a small relay under the nav station

 The wire from the Control Box to the relay would be a small, “control” wire, not a large, power supply wire. This meant power supply wiring for the intake pump would be a separate wire run than the toilet waste motor’s wiring… so the wiring to the toilet waste motor would not be burdened by also having to carry the current for the intake pump.

Since each pump had its own power supply wires, they also needed their own circuit protection. Unfortunately, my old DC distribution panel is getting crowded and nearly full. While only momentary, the power demands of an electric toilet are pretty high, so I chose to wire a new circuit breaker switch in a new space to use as my “Aft Head” master breaker rather than use any of the old, preinstalled switches on my existing power panel.

Catalina 400 Mark I DC Electrical Distribution Panel, showing push to reset circuit breakers for each row of three circuit switches
Notice the old circuits on my Catalina 400 Mark I Panel are merely protected by one push-to-reset button per row of three switches

Based on Raritan’s installation manual and the ampacity of the wiring I used, I installed a 25A circuit breaker switch as the new “Aft Head” master breaker, with a 15A push-to-reset circuit breaker for the remote pump. With a sharp-bladed macerating pump located just below the toilet bowl, being able to easily remove power from the system was an important safety feature to me. Switching off the “Aft Head” switch removes power from the whole toilet system, including the remote pump. I used a push-to-reset button to protect the remote pump circuit since it requires a lower amperage for tripping, but didn’t use a switch to avoid confusion for someone attempting to shut off the system in a pinch.

"Aft Head" circuit breaker switch and push to reset circuit breaker button
To protect the new toilet’s wiring, I installed a new “Aft Head” circuit breaker switch and resettable circuit breaker button under the bilge pump breaker

Because of the short wire runs and separate power wire for the remote pump, I could safely get away with using 10 gauge wire everywhere and still have less than the maximum 3% voltage drop. Wire bigger than 10 gauge is really more like “cable,” requiring more cost and complexity to properly connect.

The negative wires were led back to a second DC Ground Bus I had installed behind the distribution panel years earlier in an electrical upgrade. I did use yellow wires for the DC negative rather than black. New ABYC standards, which I think changed after the boat was produced, now call for yellow wires for the DC ground to make it easier to differentiate them from black AC wiring.


The “Sea-Fresh” Components

Having the option to use the boat’s onboard freshwater to flush isn’t that big of a deal to us for a few more years, and also added to installation and winterization complexity. Taking the easy way out, I only installed the relay portion of the Sea-Fresh system, and kept the other components in spare parts storage at home.

Instead of wiring in the switch to select between seawater and freshwater, I ran the “Inlet+” wire from the STC Control Box directly to the remote pump relay. When the STC Control Box wants to add water to the bowl, the “Inlet+” wire is energized, closing the remote pump relay, and activating the remote pump. Installing the switch in a few seasons from now would be easy.

Profile view of toilet, showing unused freshwater flush solenoid
The freshwater flush solenoid sits unused until we bring Priorities to salt water

There’s a solenoid for the freshwater flush that sits unused on the back of the toilet. It would be activated by the other side of the Sea-Fresh switch if I had installed it. I’d also need to run a short hose from the aft head sink potable water line to this solenoid so it would have freshwater… since this would need to be winterized every year, I didn’t install this hose, either.

Looking back on it, I should have just bought a relay for the remote pump and not bought the rest of the Sea-Fresh system until I needed it, though the additional expense was minimal.


We Like It

After a pretty simple programming procedure for the “Normal” and “Water Saver” flush options, our head has functioned well. Explaining to guests how to flush it is much easier than before… “Just press the ‘Water Saver’ or ‘Normal Flush’ button!”

The noise level from outside the head compartment is similar to the sound of the pressure water pump, which runs when washing hands anyway. I think the humming, mechanical noise during operation is less disturbing than the erratic, “squeak glug squeak glug” sound of someone pumping a manual head.

Power consumption is minimal, using 10-15 amps for mere seconds per flush, resulting in nearly no amp hours consumed from the house batteries. We have two heads on Priorities, and we’re keeping the forward head as a manual version for redundancy if there are electrical issues with the boat.

We’ve found it uses about the same amount of water as our manual head. It uses this water better, though, allowing us to prefill the bowl prior to use only if needed, and flushing more effectively. As a result, the bowl stays cleaner longer. It also reduces the “You’re pumping it too many (or not enough) times!” argument that manual heads can be infamous for, helping relations between Captain and First Mate.

Our new “Throne” is also equipped with Raritan’s Slow Close Lid… especially nice in rough seas!

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