It’s been far too long since I’ve added a post on this blog so, for this edition I’ll discuss the ins and outs of adding a Watermaker. I installed one on our vessel, a Formula 45 Yacht. If you’ve been thinking about doing this (or having it done) hopefully the following will shed some light on the exercise.
We’d been planning a trip up to Glacier Bay, Alaska for several years. A friend who’s made this trip several times advised that, although it can be done without a watermaker, having one provides a greatly enhanced level of freedom. When covering the significant distances this trip involves, the freedom to explore and alter routes is valuable. This advice motivated the watermaker installation.
While the engine room on a Formula 45 is quite impressive and well laid out for a vessel of this size, it is an engine room on a vessel of this size, meaning, there isn’t a lot of spare space! As a result, a modular installation seemed to be the best solution versus attempting to fit a pre-packaged unit into a tight-ish space.
I chose a modular system from Seawater Pro. They are a good quality, fairly basic unit that is very well priced. Depending on the model, the Seawater Pro will cost about $6k to $8k Cdn. Most watermakers in this size range will price out around $20k USD ($28k Cdn currently). These numbers do not include installation. Seawater Pro ships to Canada but at a cost ($600 +/-) where shipping anywhere in the states is free. If you can pick it up and bring it over the border, it’s worth it!
A large box containing most everything needed was received. There were a few other items required, such as a piece of Starboard to mount things on and some extra fittings for the sea strainer connection. I tied into the existing fresh water tank fill circuitry on the boat to provide an automatic shut-off feature that required an electrical relay and a couple additional fittings specific to that plumbing. There were a few other odds and sods but most parts were supplied.
Installing a modular system will likely take a bit longer and cost a bit more than a pre-packaged system, if your plan is to hire this out. If you’re a DIY person and installation flexibility is a requirement, this is obviously the way to go, in my opinion. Either way, the difference in installation costs will not be significant compared to the difference in acquisition cost. In short, I was very pleased with the Seawater Pro product and, as a DIY guy, can easily recommend them.
Without sounding like I am marketing their product, visit www.seawaterpro.com for more information, including pricing and installation instructions.
Every boat is different so what I did may not apply in every respect to what your installation requires but lots of it will be in common. I have attached some photo’s at the bottom for further clarity.
Once you’ve decided that you want or need a watermaker, knowing how they work and where and when to use them helps you determine what size you should get and how to power it. When making water, the feed water should be as clean as possible otherwise your pre-filters will get dirty and plug off quicker. This means that you shouldn’t be making water in a marina or even some popular anchorages. The best place to run a watermaker is out in a large body of water where the water is the cleanest. This infers that you will often be running the unit while running the vessel, which also means that the water inlet needs to function well at speed. It also allows flexibility for the power supply. These units can be ordered to run on DC, 12V, or 24V, or AC, 120V and 240V (as well as for European AC power). Know that DC motors cost more than AC motors. There is a less common option of running the high pressure pump off a main engine via a belt drive but that won’t be addressed here.
A rule of thumb is to be able to replace 3/4 of your water storage in 2 to three hours of run time if you’re on a faster, planing boat. If you’re in a displacement or sailing vessel, you have more time so a four to six hour guideline could be applicable. Our boat has a 100 USG water tank and travels fairly quickly on plane so I chose a 40 gph unit. The watermaker sizes are based on the number of membranes the unit has, with a standard size membrane providing up to 20 gph. So, with standard membranes they will make 20, 40, or 60 gph using one, two or three membranes, for example. The unit we chose has two membranes, rated at 40 gph.
I decided to use an AC 120V high pressure pump motor. The logic being, if we were only two or so hours between anchorages, the house batteries would not get fully charged so I would be probably be running the generator for a while regardless. Additionally, the auxiliary alternator is not quite large enough to power the unit, meaning that running it without the generator would continuously max out the alternator and slowly deplete the house batteries. Alternators are not built to run at maximum capacity on a continuous basis and we need our batteries to receive a charge not get depleted. Many of the anchorages we would be in won’t have many (or any) other boats and should have nice clear water. Because the genset would be running regularly, I opted for an AC powered unit. Alaska can be chilly (really!) so, if the generator was running, all of the heating (and AC) units would also be available. We would make water while we were travelling and make some more later (if needed) after we arrived, when the generator was running anyway. There were a few anchorages where the water wasn’t very clear but many were fine.
On the other hand, if your vessel is equipped with one or more high output alternators, providing an abundance of 12V DC power, using a DC powered watermaker can be a great plan.
As stated, the unit is fairly basic meaning it doesn’t have automatic controls. A timer is supplied to schedule fresh water rinsing but, aside from that, the unit is operated manually. An optional remote mounted control panel can be added or the base model can be operated from where it is installed. The remote panel requires wiring and plumbing connections. If you have access between where the unit is installed from where you would like to control it, ie between the engine space and the galley or helm, the remote panel is a great addition.
The bigger decisions for installation relate to raw water supply, product flow, brine discharge, and as noted above, power supply.
For raw water supply, most suppliers recommend not doubling up on an existing engine or generator cooling water thru-hull because not supplying enough water to any of these can cause damage. A recommended alternative would be to use an existing, secondary thru-hull such as an air conditioner supply. Most suppliers agree that a dedicated thru-hull is best but most owners do not want another hole in their hull!
Because of the large volumes required and the obvious importance of main engine cooling water, those inlets should absolutely be avoided. We, like most people, didn’t want another hole in our hull so I carefully examined the alternatives. Our vessel has two other raw water inlets, one for the generator and one for the three reverse cycle heating and AC units. Both inlets are the same size and both have the same size sea strainer with the same diameter piping in and out. The generator, on its dedicated inlet, requires a bit less than 300 gph. Each heating/AC pump, drawing through the other inlet, moves 710 gph for a total of 2130 gph. The watermaker charge pump is rated at 500 gph. The heating/AC raw water supply pumps can all run at the same time, demonstrating 2,130 gph is achievable. Doubling up on the generator raw water inlet results in a combined flow of less than 800 gph, far less than 2,130 gph. That makes doubling up on the generator inlet a pretty easy decision, in this case. Additionally, when not on shore power, the watermaker won’t be running without the generator so the danger of accidentally trying to make water with a closed thru-hull is minimized. I did go against the common recommendation and doubled up on my generator raw water inlet but I also ran a test to be certain the supply was more than sufficient. When running the watermaker on shorepower and having it draw water through the generator inlet, I started the generator and watched the inlet pressure gauge. The inlet pressure gauge showed a drop of only two PSI, from 14 to 12 confirming my assumptions.
Additionally, I added an inlet port with a valve between the charge pump and the sea strainer for ‘pickling’. If you aren’t planning on regular use or want to winterize your watermaker, you need to pump it full of preservative, a ‘pickling’ solution. With this arrangement, I can use the charge pump to pump the solution through the system.
Brine discharge volumes are greater than 90% of supply volumes so, not insignificant. The package supplied included a thru-hull outlet for the hull side but our boat has a manifold connected to a large outlet so I connected the brine line into the manifold rather than putting an additional hole in the side of our boat.
The product (potable water) line needs to connect into the existing plumbing or directly to the water tank. Our boat has a solenoid valve connected to a float valve in the tank as part of the water fill system that I tied into, as mentioned earlier, making it double up as an automatic shut-off when the tank is full. Without those features pre-existing, the connection can be very simple with a purely manual operation. As long as there is an overflow line, the worst that can happen if you forget for a bit, is that you pump newly made fresh water back into the ocean. If there is access to the water tank, installing a float switch with a relay into the power supply can achieve the auto shut-down function.
The power decision is about AC versus DC. As noted, I went with 120V AC power that I pulled from the main panel. Also as noted, I opted for the optional control panel which, as part of the panel, has two properly sized AC beakers, one for the charge pump and one for the high pressure pump. The charge pump is a 12V DC pump so its breaker controls power supplied to a 120-12V AC/DC transformer (needs to be purchased separately). The other breaker controls the power supplied to the larger, high pressure pump. Wiring size needs to be appropriate for the expected loads. If a DC system is chosen, the power required will need appropriately large cables and a capable supply location with properly sized breakers.
Once those decisions are made, you’re ready to order your watermaker and, by virtue of your decision making process, you are also partway through planning your installation.
I’m assuming at this point you’ve already identified a suitable place for installation and the next task is to figure out how to mount all the equipment. Starboard (high density polyethylene sheet, or HDPE) is a very useful material for this. I purchased a 3’x4’ sheet of 1/2” thick white Starboard and used most of it. It’s a bit pricey but so versatile. It is impervious to water so it does not corrode or rot and it is quite strong. I built a frame that I could attach to the interior of the engine space in a several solid places which provided the needed mounting spots for the high pressure pump and motor, the membranes, the pre-filters and the charcoal rinse filter/timer. Because I did not have reasonable access for a remote location, and I had plans for an auto shutdown, I installed the remote panel in a non-remote location. I built a box from Starboard and mounted it in the engine room! I wanted the panel for the controls associated with it more than a using it in a remote location.
With good advance planning, the install should go smoothly but the amount of time needed can easily be underestimated. Crawling in and out of small spaces and fishing wires and hoses through boats takes longer than most expect. on the positive side you will get know your boat a lot better and have a valuable option available to you for longer, more expeditionary type cruising.
If you aren’t the DIY type, make sure the installer walks you through the details of what they did and how the system works.
Here are a few photos.
The heart of the unit, showing the HP pump bottom left, pre-filters in the center, reverse-osmosis membranes at the top and the rinse timer with charcoal filter on the right. They are installed around the existing equipment (macerator pump, vacuum generator and cord reel tub). The white Starboard can be seen below and behind the HP pump and to the right of the membranes. Although out of view in the photo, the Starboard is continuous from left to right behind the membranes, providing a place to mount the filters. It is firmly attached to the boat at each end as well as bolted down at the bottom.
The photo above shows the water supply inlet and associated piping with the sea strainer to the right, flowing out to a cross. There is a step that folds down over the cross and valve. The bottom outlet on the cross supplies the generator with cooling water. The charge (or boost) pump can be seen to the left connected to the HP pump with blue supply tubing. The top of the cross has the capped valve used to feed preservative solution for pickling. As can be seen in the first photo, the filter casings have the filters removed and are full of pickling solution.
The control panel that can be mounted remotely (but is not, in this case) has power supply breakers, pressure gauges for both the boost and main pumps, a TDS (Total Dissolved Solids) meter and a flow meter. The metal ‘T’ handle is used to adjust the main pressure, starting low and increasing up to the 800 PSI operating pressure. The white diverter valve on the right is used to send product overboard that is not pure enough (>TDS of 200 ppm). Once the pressure is up and TDS is below 200 ppm, the valve gets changed from Bypass to Tank.
Once the tank is full a relay, as noted earlier, remotely cuts the power supply and the unit shuts down. If the breakers on this panel are not turned off, when the tank sees some usage and the ‘Tank Full’ indicator goes out, the unit will start up again (providing there is AC 120V available), even though the tank is almost full. This is not detrimental but also not necessary so I have to remember to turn off the breakers until we need to make water again. The manufacturers instructions indicate that, if restarting within a day or two of last use, leaving the pressure settings in place on shutdown will allow the unit to almost immediately deliver potable water on startup. No adjsutment needed, just turn it on.
Hopefully this was helpful. If you need some additional help or advice, contact me at murray@oceanicyachtsurveys.com or call my cell (403) 815-1415.