How Much Water Will My Liveaboard Family Use?

[GhostChaser]

Hi All,

As way of background I have purchased a new 40 ft catamaran in France and will be sailing it back to Australia over the period of a year with my family (2 adults and 2 kids 11yrs and 9 yrs)

I am in the process of optioning the boat and the watermaker is proving to be the biggest intellectual challenge.

In all the litereature I read, the first question I need to answer is how much water per day will we use? To be honest, I have no idea as we've neve done this before


(1) Can someone please advise me on the typical daily family water use in litres for a liveaboard family.

- Daily showers for all 4 people
- Drinking
- Washing Machine (for clothes and linen)
- General cleaning
- Washing down boat


(2) I will have a 5kw genset with 600w of solar. Based on teh above would you recommend a AC or a 12v system?


Thankyou.

[Randyonr3]

between my wife and I, we use between 12 and 15 gallons per day, we dont wash down the boat with fresh water until we get to a dock where the water is accessable for such.
We've also had a 12 volt watermaker but have decided to go with a large 110 volt unit and a genset this time..
Maybe we can get Rich to chime in on this one.. hes got the unit to use and the experance behind it...

[J Clark H356]

My wife and I also average about 15 gallons (66 liters) a day. This includes showers for 2 and washing dishes. Dish washing for us while cruising is minimal as we use disposable paper plates of high quality more than unbreakable china that requires washing. We find dish washing is a major water use due to rinsing time. We also use water for cooking and drinking. We do not have a washing machine and don't have a fresh water wash down as our wash down is from a thru hull and only fresh when river cruising. My guess is that you would use between 35 (154 liters) to 50 (220 liters) gallons per day. Your wash down could obviously raise your demand depending on how extensive your wash down efforts were. A wash down pump is typically 3.5 15.4 liters) gpm, so 10 minutes is 35 ( 154 liters) gallons of water.

We have a 5KW Northern Lights genset but no watermaker, and 80 gallon (352 liters) water capacity. We run our generator full time when cruising to keep the interior in conditioned air. We have never been out longer than 100 hours between shore power. If I got a watermaker, I would also put in a fresh water wash down from a separate tank and feed my electric toilet with fresh water instead of seawater as well. I would get a CruiseRO 120V 40 gallon (176 liters) per day if I were you. On average you would be able to replenish with about 1-1/4 to 1-1/2 hour per day watermaker run time, with an occasional longer time if an extensive wash down was needed. Our generator uses about .25 (1.1 liters) to .3 (1.3 liters) gallons per hour.


Sent from my iPad using Cruisers Sailing Forum

[SV THIRD DAY]

We are on year 7 of full time living aboard with a family of 4.
When we headed out the kids were 9 and 10 and in the warm weather of Mexico with washing machine, fresh water deck rinsing at anchor, and at minimum 4 daily showers we have been using on average 25GPD. We used more in the warmer weather for the extra rinse down of dive/snorkle gear after lots of swimming than we are using now in "cold" California, but we also use more water for laundry.

As a manufacturer of 120v AC high output water makers, I obviously have a bias in that direction, especially if the boat already has a generator. The concept once you go 120v AC is to make as much water as quickly as possible to minimize generator run time and tie it in 2-3 times a week with battery charging.

To give you a good understanding of the general 120c AC water maker concept/layout and design, you can download a copy of our 30GPH water maker, which is our most popular selling unit by far.
www.cruiserowaterandpower.com/uploads/sm30.pdf
I'm not trying to overhype our 120v AC unit over other quality brands like EchoTec, there are lots of many good 120v AC units on the market. Some can be controlled by your Ipad/Iphone or James Bond smart watch and obviously cost a lot more that our totally manula unit with no electronic controls. Some appreciate this KISS approach and pricing structure, while others what the full automation and have a few extra thousand dollars in the water maker budget.

I can't say what is the "best approach", I just know what works for us and our clients.

[Emerald Sea]

For our family of four (adults) we have calculated that our freshwater needs on our Lagoon 450 are between 90-110 liters per day (23-29 US-GPD). We have a AC/DC watermaker that delivers up to 100L/hr and I run it every day or 2nd day. We typically take rationed showers once a day, use the washmachine every 2nd or 3rd day (reduced cycles), wash dishes with seawater (sometimes) and rinse with fresh, cooking and drinking water make up the rest. We wash the decks when it rains and use a FW squirt bottle for washing rigging, blocks, clutches,etc.

As we have only 2x 175L FW tanks I always maintain one tank full in event the water maker goes down. We have 3x 25L jerry cans available with FW.

Steve
S/V Emerald Sea
L450

[GhostChaser]

Thanks all. The averages give me a good feel for usage. If I budget on 100 to 120 litres to day worst case I should be fine.

Therefore the AC 30gph unit looks and perfect and it makes sense why its the most popular unit. Thanks Third Day.

[Kenomac]

We live at anchor four months continuous per year, never going to shore to plug in. We use 50-60 gallons per day for two of us which includes showers, dishes, drinking etc. laundry uses about 10 gallons per load when used. Using a bathroom sink adapter, I can wash down the boat with 25 gallons or less. We have a Spectra 380c otherwise known as the Catalina model I think which produces a max of 17 gallons per hour. Actual is less here in the Med. You will need a larger capacity water maker unless you plan on running it at least 6 hours per day. We need to run our 5kw generator 2-3 hours per day. Plan to do all electric cooking, washing machine, water maker etc. to create a load for the generator during the generator run times.

Something New I learned just yesterday from Spectra. Make sure you have a forward scoop type skin fitting installed for the water maker intake thru hull... Otherwise you will create an air lock in the system while underway, making the water maker shut down or produce very little water. Since you will be underway all the time... This is very important for you. You can actually break the pump if it's left to cavitation for an extended period of time.

Bring along spare parts for everything water maker related except for the membrane. Pumps, pump rebuild kits pre filters, connection fittings and Clark pump rebuild kit.


Ken

[SV THIRD DAY]

I always try and talk to our clients to understand the "why" of their purchase decisions and then follow up with them to get some feedback and where's what I'm finding along with my thinking.

The SM20 (20GPH) and SM30 (30GPH) both use the same high pressure pump and motor, a 1.0Hp motor that uses 9.3A at 120v AC (motor can also run at 220v). So if you look at it from a Amp per gallon standpoint you are making 50% more water for the same power usage with the SM30. There is also some built in membrane redundancy in the SM30. If one of your two RO Membranes were to fail while out cruising, you can quite easily just run the water maker off of one RO Membrane and continue the cruise with a 20 GPH water maker. The cost difference between the SM20 and SM30 is $855, so between the 50% production increase (or 50% less generator run time) and the redundancy it’s a compelling argument. Literally, the only difference between the SM20 and SM30 is the addition of this second RO Pressure Vessel and Membrane plumbed in series. The SM40 is the SM30 but with a larger pump and motor. Of course you can always upgrade from a SM20 to a SM30 at any point down the road for the same $855 price difference, so there really isn’t a “risk” in starting out with the SM20 and we have folks make this upgrade all the time because well, salt water is evil! But honestly, if you can afford the initial $855 upfront I think it makes the most sense, especially with a crew of 4!

The mindset of a 12v water maker is “energy efficiency” since you are trying to make water solely off or your battery bank, so you live with less production per hour to help keep down the amp draw. With a 12v water maker, Amps/Gallon is a key yardstick of performance. But once you have the power of an AC Genset, sure you want efficiency, but it is no longer the governing criteria and Amps/Gallon of production water just isn't as important because you usually have power to spare while running the genset. With an AC 120v water maker, it just makes sense to make as much water as quickly as possible to minimize generator time or make more water to keep the tanks full. There were times when we were hanging out in a chocolate water estuary where we didn’t make water, so once our 450 Gallons of tankage was gone, we would head out of the estuary for the day to refill the water tanks and then head back in at the end of the day. With a low output 12v water maker it would have been difficult to “catch back up” once the tanks were ran dry.

Spectra makes a great water maker and like us, has great customer service, so I can't ding them at all, nore can I or anyone match their Amps/Gallon numbers! So for a boat without a generator and just a battery bank, I send those folks to Spectra and know they will be happy. Sure they will have less water, but that is the best match for their boat. I think once you make the decision to have a generator (or Honda 2000) then an AC 120v water maker like one of ours is the way to go. There isn't a "wrong way" to go in the 120v vs 12v water maker decision as long as you know the decision tree and strengths and weaknesses of each approach. You wouldn’t buy a 120v AC water maker with a 400AH battery bank and 300W of solar without a generator, just as I don’t think it makes sense to buy a 12v 17GPH water maker if you have a ships genset that you run regularly and have a >20+ GPD water demand.

A possible knock on the 120v AC approach is that if your generator dies so does your water maker. Well maybe...but if you buy a unit that can't run from a 2000W inverter powered by your alternator and battery bank, you have a back-up powering source. This is why the SM30 is a better seller than the SM40, I think. Sure the SM40 makes more water per hour, but it also uses a 1.5Hp motor at 13.3A so that takes it out of the powering range of most inverter/alternator as a back-up for if the genset dies. I was explaining this to a cruiser last week and his response was, "Son, if my generator dies our air conditioning is also out and we are heading back to the dock anyway, so sell me that SM40"! As someone who spends the summers in the Sea of Cortez in 110-deg heat without air conditioning, I had to laugh, but it shows the differences people have in what they need that works for THEM. Sure some can live with a 500ml shower every other day, but I can call you for a fact that we would not be on year 7 of full time living aboard if I had to ever tell my wife and daughter to take shorter showers. Our love life would be a lot less without nice comfortable showers...hot stickey my friend means you don't get any...ha ha ha). What we do is run our Honda 2000 or 8K diesel genset when at anchor to make water, but while underway motoring we flip on the 2000W inverter to make water. This way we entered the anchorage with full tanks.


You can reach me 7 days a week pretty much whenever I’m awake for technical support/Customer service, it’s the advantage of me being a live aboard cruiser, I’m always looking for an excuse to get out of a boat project and talk cruising and water makers! Rich@cruiserowater.com

[GhostChaser]

Kenomac
- The bathroom sink adapter you mention, is this something you sourced from a hardware store or something more specialised?
- Really interesting point you make about the front scoop intake to prevent air locks. Have not heard this before and certainly relevant as doing two large ocean passages.

Rich
- Do you have a view on the second point and is this a fitting you supply or a standard through-hull fitting?

[SV THIRD DAY]

Originally Posted by GhostChaser

Kenomac
- The bathroom sink adapter you mention, is this something you sourced from a hardware store or something more specialised?
- Really interesting point you make about the front scoop intake to prevent air locks. Have not heard this before and certainly relevant as doing two large ocean passages.

Rich
- Do you have a view on the second point and is this a fitting you supply or a standard through-hull fitting?

Some points are water maker model specific, like the forward facing scoop. Our boost pump is strong enough to not need the scoop, and I think that is just part of our design philophsy of not needing to be as "energy efficient" since we are not trying to power the unit form 12v. We have oversized the boost pump so that it always can keep the Hp pump with a positive supply of sea water in all conditions. We do recommend a 3/4" normal through hull which makes servicing and cleaning easier.

[Albro359]

Wow, you guys use a hell of a lot of water !
We have a Dessalator 60 (60l/hr) and we only run it every second day for about an hour or hour and half...and that's with 3 to 4 adults on board !
We don't use the washing machine much...we don't wear that many clothes!
Showers are SHORT ! 2 minutes is our rule
The Dessalator runs off both 220VAC and 24VDC, so we can run it with either the genset or the engine running.
We have a 1000 litre water tank, but we maintain it at about 600 litres.

On our previous boat we had only a 250 litre tank and a 35 l/hr 12VDC watermaker...usually 2 to 3 adults on board, the water tank was always full.

[Kenomac]

One more thing to consider, if you want to live like you're camping all the time, buy a water maker to fit your minimum needs. If you want to live more like you're at home, upsize the water maker... You'll never be sorry that you did.... Unless you want to spend all your time being a water nazi. It's small money when you consider the cost of the entire boat. The same when you pick out your anchor. Go one size up.

Note: Women don't like water nazis.

[Kenomac]

Originally Posted by GhostChaser

Kenomac
- The bathroom sink adapter you mention, is this something you sourced from a hardware store or something more specialised?
- Really interesting point you make about the front scoop intake to prevent air locks. Have not heard this before and certainly relevant as doing two large ocean passages.

Rich
- Do you have a view on the second point and is this a fitting you supply or a standard through-hull fitting?

My wife purchased the quick release hose adapter from the Home Depot hardware store. Probably available online. Then we connect it to one of those expanding hoses. So the entire contraption tucks away in a very small plastic bucket.

You will need to wash down the boat every couple of days while in route.

[Kenomac]

Originally Posted by SV THIRD DAY

Some points are water maker model specific, like the forward facing scoop. Our boost pump is strong enough to not need the scoop, and I think that is just part of our design philophsy of not needing to be as "energy efficient" since we are not trying to power the unit form 12v. We have oversized the boost pump so that it always can keep the Hp pump with a positive supply of sea water in all conditions. We do recommend a 3/4" normal through hull which makes servicing and cleaning easier.

The Spectra unit is about as energy efficient as water makers get as I understand them. The problem created which necessitates the forward facing scoop is not caused by a pump issue, it's caused by the water vortex created over the flat through hull fitting when water on the outside of the hull passes by while underway. We noticed that when we cruise along at 4-5 knots our water maker was producing only 10-12 gallons per hour, and when we increased speed and heel to over 7 knots, the pumps sometimes went into cavitation. The water velocity over the flat through hull at 7-8 knots is probably even greater due to hull shape and acceleration. This however, does not affect boats which make water at anchor or travel slow. The OP might want to make some water while traveling in excess of 5 knots while underway to the land of OZ, so this might well be a consideration. It's a simple, almost no cost fix. Install one type of fitting or the other. The scoop with screen will service all situations.

Ken

[John Casey]

Originally Posted by SV THIRD DAY

I always try and talk to our clients to understand the "why" of their purchase decisions...

I'm glad I stumbled across this thread.

And thanks to Rich for all the great info about watermakers. I've now filed this away for future use.