MacGregorSailors.com

What you actually fell for that???
Yea. Yea I did. Check out “quenchsea” and roast me for being gullible. I have not received this yet. A perusal on YouTube reveals several prior models that they claim function, and are demonstrated on a kitchen table. I’m not sure which model I will be shipped, but the shopping cart indicated it was the latest model ver.2 which looks a bit better and supposedly is easier to pump. It’s rated for about a gallon an. Hour, but I plan to motorize mine instead of pumping it. The website has some enlightened speel about helping water impoverished people but no one’s going to lose money and stay in business. Engineers on the forum: is it possible to make a 160 desal unit and sell it at a profit?? On wait! They claim they Donate a unit for each one sold. That means they have to produce it at 80 dollars just to break even.

Ix

$160 initial purchase
$60 / year replacment RO membranes
$40 prefilter. Replacement time will depend on original water quality.

It was offered a couple of years ago on IndieGo for around $70 so $160 for two (one for you, one for them to give away) is in the same ballpark. When you factor in any tax breaks they get from the giveaways they are not losing money even at this price. US base is in California so they are likely paying the 8.84% corporate tax rate.

I remember following an early version of this when it was still being crowdsourced. As I recall, it had some initial QC problems and the output claims were a little optimistic but it did produce drinkable water with a reasonable amount of effort. I don't know anything about the current version but I do recall that a recurring comment of the original version was, "It's bigger than I thought it would be".

There is no reason to expect it won't work but the output claims should be taken with a grain of salt (pun intended). When a product says "up to 1 gallon per hour" I read that as "under no circumstances will it produce more than 1 gallon per hour". If you count on half the maximum you probably won't be disappointed.

As a business model, I would categorize it as the inkjet printer of the water maker world. Sell the original product at a slight profit and make your money over time selling the consumables required to make it work.

From an engineering standpoint the problems that low cost water makers run into is longevity. These RO units need to around 700 psi to work so the seals are usually the first thing to go. It's not hard to engineer an RO device that works but it is difficult to make one that will keep working over time. The difference between this and a $1000+ version is not technology but build quality (and overhead).

If I were putting a water maker in a life raft, this would not be my choice. For those of us where a water maker is more of a convenience than a necessity, it's probably fine. I (tentatively) absolve you of gullibility.

Hi Be Free!

Great points on the required pressures and filters that need to be changed…

Similar things have come and gone over the years with desalinization using reverse osmosis methods.
The Achilles Heel of them has always been the durability of the seals and pump.
Getting enough potable water out has always been limited.
One gets tired with forcing a hand pump to manually raise the pressure.

One of the more interesting of these recent spate of limited cost RO systems has been a reincarnation of the diving foot ball.
One starts with an empty container with a one way (inbound) pressure relief valve cap.
Seal the container and lower it over the edge … when the container get to about 4000 ft of more the relief valve opens allowing seawater to enter and forces it through the filter by differential pressure. After the container is full you haul it back you.

Best Regards
Onereasy

4000 feet huh? I'd have to go 170 miles offshore to find that. I think I'll just carry a few more bottles.

Oppsies!

Ladies and gentlemen…. May I have your attention please….
It appears that I have succumbed to a case of FFT ( fat fingered typing )….

The prior post stating ”4 0 0 0 feet”should have been properly stated as ”4 0 0 feet”

Thanks for catching that Be Free!
My bad
My boo-boo.

Best Regards
Over Easy

For those interested in a DIY compact thermal desalination unit one can make for that rare “just in case” scenario…



From a Design Engineer’s / former Medic / back area camper perspective there is couple of options…
Now for those who can see where this is headed there is a VERY SIMPLE emergency desalination system one can make simply by using.
The one I’ve found easy to use with a minor bit of “MacGyverism” and without permanently altering anything (so you can still use things for their original purposes.
Materials:
1) a pressure cooker
2) about 5 to 10 feet of 3/16”-to-1/4” I D silicone rubber tubing
3) a bucket or water can or pan that can hold cold water
4) a container or bottle (or other collection vessel) to collect the distilled water
5) a heat source that one can safely and stabilize the pressure cooker
6) small zip tie or wire twist tie (like from a loaf of bread) — this is optional

Set-up:
—>> NOTE: This process involves heat and temperatures and potential pressure. CAUTION is required to avoid any potential burns, scalds or other potential injuries. You are responsible for your own and others safety when choosing to do this!
A) Take the pressure pot lid and slip the silicone rubber tube over over the center vent tube
—>> NOTE: If you want/need to, cinch the tubing to the vent tube with the zip tie or twist tie
B) Route the mid section of the silicone tubing into a pan, pot, sink, or water can (condenser) with the free end running into the collection vessel
C) Fill the condenser with cold water
D) Take the lower portion of the pressure cooker with an inch or so of water in it and properly attach the lid with its seal (now with the tubing)
F) Place the pressure pot safely and stably on the heat source
G) Heat the water in the pressure cooker to a light gentle boil JUST SUFFICIENT to raise the little pressure button then reduce heat just so that the pressure button remains raised. You want to AVOID ANY EXCESS PRESSURE beyond the minimum of what is needed to generate low pressure steam.
H) The steam generated will flow through the tubing, condense and collect as pure distilled water.
—>> NOTE: As the distilled water is now fully demineralized one should add back a small amount of table salt, about an 1/8 of a teaspoon per gallon, otherwise prolonged drinking of distilled water will demineralize you!!! Not a good thing!
I) Stop heating BEFORE the pressure cooker RUNS OUT OF WATER!!!
J) ALLOW THE PRESSURE POT TO FULLY COOL NATURALLY BEFORE OPENING, RISING, CLEANING AND REFILLING

DISCLAIMER: Anyone choosing to do this does so at their own risk and safety. Anyone choosing to do this is responsible for doing this in a safe and responsible manner. Anyone choosing to do this assumes all and sole liability for doing so for any personal harm, injury or damages in anyway, shape of form. It is to be understood that any of this information and suggestion is provided only for informational purposes on a potential means to generate distilled desalinated water for an emergency basis.

This is just a means by which one could generate distilled water with simple items one might have available already or might choose to get or assemble to generate drinkable distilled water from saltwater.

Best Regards,
Over Easy

Very interesting. I'm tempted myself tbh, for our upcoming Bahamas trip. It looks like a LOT of pumping for a single glass of water, though, according to the videos on the site. On the other hand, I'll be in the Bahamas with my then 17 and 19 y.o. sons so I don't really care about the pumping effort.

The cheapest motorized RO desalinator I could find is the Katadyn Powersurvivor 40e, at $4k USD. They also make the Survivor 35 manual-pump unit at $2.3k USD. That price difference pays for a LOT of filters and membranes.

Curious as to how you plan to motorize it, Ix?

Re heating: I deemed that too fuel demanding for my needs
Re motorizing: eBay has a lot of gearboxes and reducing drive units. I think I can find a 12 volt motor that will drive that, attached to a Starboard eccentric. However, someone with a home shop may be able to make something way better. A lot depends on the build quality. If it’s poor, I won’t bother. I plan to mount it in my new bathroom which is looking more likely to happen. I can run it while I soak in salt water, then rinse in fresh. Like the affordable 12 volt coolers, this may really be able to improve life on a small boat.
Ix

Ixneigh wrote: ↑Mon Apr 22, 2024 7:04 am Re heating: I deemed that too fuel demanding for my needs
Re motorizing: eBay has a lot of gearboxes and reducing drive units. I think I can find a 12 volt motor that will drive that, attached to a Starboard eccentric. However, someone with a home shop may be able to make something way better. A lot depends on the build quality. If it’s poor, I won’t bother. I plan to mount it in my new bathroom which is looking more likely to happen. I can run it while I soak in salt water, then rinse in fresh. Like the affordable 12 volt coolers, this may really be able to improve life on a small boat.
Ix

The units that are engineered to be driven by electricity claim to use around 2Ah per gallon so plan on at least that amount of power consumption. That is probably as good as they get under ideal conditions in the lab. YMWACV (your mileage will almost certainly vary) and it won't be lower.

I'm interested to see what you come up with.

Another option is a wind mill driven linkage. The de sal unit appears constructed entirely from plastic. The wind mill could drive a reduction gear fixed to a crank. The unit could be clamped vertically to the windmill pole. Maybe with a canvas cover. But it won’t corrode from exposure to the elements. It could be let to run even when the boat is not occupied since there is no electrical involved. One could return to the yacht after a few hours exploring in the dinghy to have several gallons of water ready, at least in the average winds of my area. It would probably not need a large propellor although someone clever in here might be able to work out the ideal size.

Ix

Hmmmm……. wind powered pump driver……..

There are a couple bits of info needed to be had before looking into this further …..

A couple of questions…..
Q1: So exactly how many pounds of measured force is required to fully compress the pump lever with the system loaded with seawater as measured 1 inch from the end of the handle?
Q2: Exactly how many pounds of measured force is required to fully lift the pump lever with the system loaded with salt water as measured 1 inch from the end of the handle?
Q3: What is the length of actual full down stroke of the pump lever measured 1 inch from the end of the pump handle?
Q4: Does the pump self prime?
Q5: How high can the pump draw in seawater? (AKA: Suction head height capability)
Q6: How high can the pump discharge fresh water? (AKA: Discharge head height capability)
Q7: Does the pump lever compression force increase from a neutral level discharge of fresh water to that of a maximum height discharge? What is the peak force measured?
Q8: Does the pump lever lift force increase from a neutral level intake of salt water to that of a maximum height intake?
What is the peak force measured?

With answers to the above one could begin to evaluate the feasibility of an operational wind driven pump drive system and at what wind velocities would be needed to drive it….a pinwheel or 50 Megawatt turbine? ….. a 5 knot breeze or Cat5 hurricane?

Just as an added bit to consider is that the wind drive system would need to articulate around a vertical axis as it would need to point into the wind for a horizontal shaft approach …. A vertical shaft approach avoids that but comes with its own set of challenges…..

Best Regards,
Over Easy

Going back to what I remember about the first versions of this unit most of the early commentators indicated that it was a lot easier to step on the handle than it was to try to use your arms to compress it. Maybe this one is a little easier to operate but I can't imagine that it is much easier.

Just for discussion sake and to keep nice, round numbers, let's assume that all of the power requirements in the previous post come out to 1HP.

Power output for a wind turbine varies directly with the square of the blade cross sectional area and the cube of the wind velocity. I calculate you would need around 10 knots of wind on a 3 blade turbine with 1 meter blades to get 1 HP output. I'm speaking as a hobbyist, not an engineer, but I think those numbers are pretty close. The 1 HP number may be high but even cutting it in half it only brings the wind velocity down to around 8 knots.

These numbers assume reasonable, real-world efficiency in the turbine itself but it does not account for the non-trivial losses that the power train is going to introduce as you step down the turbine shaft speed to get enough torque to move the handle on the RO device. It is beyond my skills to calculate those losses but my gut tells me that they will be significant.

I don't think it is impossible to drive this device with wind power but it is going to be an interesting process. Fortunately a lot of the wind driven engineering was done a long time ago. You just need to scale it down to boat-size. You are probably going to want to use more than the three blades in my previous example. You will lose some efficiency and be noisier, but you should be able to generate more torque at the same wind speed.

Oh! All these are great points to think about. Thank you, gentle men. Maybe tie a line to the handle and put a bucket on the other end. Let the boats gyrations at anchor do it

Hi All!

Be Free is on the right path and it gets more challenging when adding in the “in”efficiency losses.
The best one could consider would be a 40-to-50% efficiency (and the reality would probably be much lower than that depending on which design route was chosen to pursue such as eccentric lobe or gearbox or belted pulley.)

The use of a cable link to the anchor and using wave action isn’t all that far fetched as, depending upon the anchor mass and how well its dug in, could generate enough force through wave action, but the waves required would really make the ride a bit uncomfortable.

The 1 hp motor aspect (if correct) could possibly if geared down enough might work, but to make up for the mechanical losses one should be looking at more likely a 2 hp motor. Using solar panels and batteries to provide the electrical power would really drive up the costs and most likely still run flat in short order. A better RO desalination system could reduce the force required but a better system also costs more. One of the inherent problems with RO desalination…but some water (even if you’ve got to work for it) is gonna be better vs no water at all.

One could always consider a solar still desalination approach for small batch production. There are several out on the market available but most are of the “survival” type and relatively small. A derivative option could be the use of a solar oven and a water boil/evaporation approach. The trick is getting it to track the sun cost effectively for prolonged periods of time.

Sorta explains why the systems out there aren’t all that popular in use or inexpensive… except maybe as a limited emergency backstop.
The aspect of simply storing sufficient water aboard for the expected duration at sea between replenishment stops is/has-been generally the more effective approach for many sailors and cruisers. Flexible bladder tanks with soft padding to prevent chaffing or pin holes can allow a considerable amount of water storage in the odd shaped areas often under utilized on our MacGregors and other vessels.

Your boat/your rules…

Best Regards,
Over Easy

I found this really neat 12 volt motor at work with a worm drive on it. But it don’t think it is one HP. Heck I’m not even sure I am one HP. Since I’m not a horse even…Now I’m wondering if I’ll even be able to operate this unit for more than a few minutes

Ix