Water in the Pacific

[owly]

It requires .58 hp to pump 1 gallon per minute at 1000 psi, which is approximately the pressure required for a watermaker. A healthy human can produce about .1 HP indefinitely, and .25 to .5 HP in the shorter term. This requires a decent way to produce that power, such as a pedal or rowing type system. That means that at a very low power output that one can sustain indefinitely.... of .1 HP, it would take about 6 minutes to produce a gallon of water. This is very different from the small crude survivor type watermakers with a hand pump and tiny membrane. It is in fact very doable for a person or crew to produce far more water than they really need using pedal power. A half an hour light workout would provide not only all the water you need and then some, but enough for a nice fresh water shower.
People pay money to go to a gym for a workout that has no "product" except exercise. It only makes sense to produce fresh water as a "product" or byproduct, and stay in shape on a voyage...... Interestingly I seem to be the only person who thinks so......



H.W.

[a64pilot]

Your not actually, however this is about the time this video is brought up, showing just how little power a person is capable of producing, although this guy is far from normal, average person is likely to produce 1/10 the power.
As a kid we had a bike generator set up that you could power a light bulb or a tiny TV etc at the school I went to, not many could run a light bulb for long at all.
https://youtu.be/S4O5voOCqAQ

[lizardofoz]

I find DC more recreational and they all seem to battle to get high output and are generally x the litres product water produced expensive. If you consider the costs a smart 12VDC system full of can only buy from the manufacturer expensive components against a more conventional simple can but parts anywhere system that is smartly put together / but uses more amps and is 230V - marry that to a decent array of solar panels and a decent battery bank and a decent inverter - add all them together and you come up with more product per hour - possibly double , less running time and no more expense. And when the time comes for a repair or replacement part the expense is minimal instead of exceptionally expensive.
With this system its compact in its own shell - would take some engineering to belt drive it from your main engine. Just go to Rainman Desalination for all the specs and or email them - the owner Ron is very responsive

Originally Posted by john61ct

Not possible to buy the direct belt drive unit to get fitted to your own motor / PTO?

And see if you can find the wattage required for the two AC electric powered options.

Strange there is no high-output DC powered option, Rich @CruiseRO will accommodate that on request for his similar-sized output models.

[john61ct]

But sizing the watermaker system to match what the owner can effectively sustain for say 40 minutes may well be doable.

Later on fitness will increase.

However room available on a small boat will be an issue for many.

Plus of course you might need to carry more calories per day.

Hmm, could be a marketing point, fitness charters, put the crew to work like in the America's Cup 8-)

[owly]

Watermakers use the same basic pump design as a pressure washer. For anybody who's interested, the math is pretty simple. Horsepower required equals pressure in PSI times flow in gallons per minute, all over the constant 1710. One horsepower equals 745.7 watts. There is absolutely no reason under the sun that a specific pump volume needs to be used to feed the membranes of a watermaker. Pump and belting can easily be set up to match the power available. It makes sense to size and belt your pump to match the solar power you can generate. There is no rocket science involved, just a pump pushing prefiltered seawater through a membrane at about 800 to 1000 psi. A simple valve system allows you to run fresh water through the pump and reverse the flow to flush the system afterwards. It makes sense to build your own as you can fit it to available and convenient spaces.


H.W.

[owly]

Originally Posted by a64pilot

Your not actually, however this is about the time this video is brought up, showing just how little power a person is capable of producing, although this guy is far from normal, average person is likely to produce 1/10 the power.
As a kid we had a bike generator set up that you could power a light bulb or a tiny TV etc at the school I went to, not many could run a light bulb for long at all.
https://youtu.be/S4O5voOCqAQ

Great Utube!! The cyclist was putting out about .94 HP, almost 10 times what an ordinary person is said to be able to put out long term. That brief workout would have yielded theoretically 1.6 gallons of fresh water per minute. I didn't have any way to time it, but I'd say a bit over 3 gallons of fresh water.........not too shabby! An ordinary person pumping out an easy .1 hp should be able to generate a gallon in about 6 minutes, or ten gallons an hour.


H.W.

[owly]

Originally Posted by john61ct

But sizing the watermaker system to match what the owner can effectively sustain for say 40 minutes may well be doable.

Later on fitness will increase.

However room available on a small boat will be an issue for many.

Plus of course you might need to carry more calories per day.

Hmm, could be a marketing point, fitness charters, put the crew to work like in the America's Cup 8-)

I visualize a piston pump that you row with a rowing machine that you also use in your dinghy. Sort of like the Oar Board https://www.oarboard.com/ That would give you a better full body workout, as well as having a dual function.... as you suggest, finding space might be a challenge. Alternatively a pedal assembly with pump could be set up in the cockpit that could be operated from one of the cockpit seats. It would attach to the rest of the system via quick connects. The actual membrane assembly could be located in a cockpit locker....... As with anything, what makes sense for one person may not make sense of another...... an interesting challenge I think.


H.W.

[a64pilot]

Originally Posted by owly

Great Utube!! The cyclist was putting out about .94 HP, almost 10 times what an ordinary person is said to be able to put out long term. That brief workout would have yielded theoretically 1.6 gallons of fresh water per minute. I didn't have any way to time it, but I'd say a bit over 3 gallons of fresh water.........not too shabby! An ordinary person pumping out an easy .1 hp should be able to generate a gallon in about 6 minutes, or ten gallons an hour.


H.W.

Well my Watermaker with a 1 HP electric motor can make 30 ish gl an hour, 1/10 that if it scales is 3 gph.

Vast majority of the water is wasted of course, fresh water is only a portion of what is pressurized, the rest is rejected and I believe serves to keep the membranes clean.

Also if memory serves it draws way more than 750 Watts, 750 Watts may equal 1 HP, but unless 100% efficient your not getting 1 HP from 750 Watts. So I’d be surprised if you could make much over 2 gph, and that’s working pretty hard, plus I have no idea of efficiency of mechanical contraption much less the generator.

I’d assume the cyclist in the video due to inefficiencies was making over 1 HP, which of course makes him a real beast, did you see how he was flexing those bars, his whole body was into it, and I doubt a normal person could flex the bars at all.

Really makes you appreciate just how much actual power your getting from say a Kilowatt of Solar panels, or how much power a little Honda really is.

[a64pilot]

Found it, my 1HP water maker uses 1100 Watts, and it’s a very efficient motor.

[john61ct]

Originally Posted by owly

It makes sense to size and belt your pump to match the solar power you can generate

Unless solar is a small fraction of your overall energy produced.

Personally, I only want to run the watermaker while my ICE power sources are also running, and if that can be kept under 6 hours a week, that would be ideal.

So 40+ gph (actual fresh water produced) would work better for me, and neither noise level nor energy efficiency is a consideration for me in choosing a watermaker.

[westsailwill]

Originally Posted by Eder

Hasn't rained much here in the Society Islands last few weeks. Water is a pain to get in the Marqueses and Tuomodus but not impossible at all.
Your boat is large enough & you already have a generator ...its a no brainer to add an ac watermaker.

We run ours about 3 hours/day....use about 60 gallons water/day.Life is good.

No matter your perspective, access to too much water is never a bad thing. Glass half empty, or half full... you decide🤓

[SV THIRD DAY]

Originally Posted by westsailwill

No matter your perspective, access to too much water is never a bad thing. Glass half empty, or half full... you decide🤓

Two comments I've never heard cruisers make.

1. I have too much solar on my boat.
2. My water maker makes too much water per hour

Of course the converse of those statements is commonly disgusted in cockpits around the anchorage's of the world

[SV THIRD DAY]

Originally Posted by owly

There is absolutely no reason under the sun that a specific pump volume needs to be used to feed the membranes of a watermaker. .

That statement is completely and utterly false. However, since the poster was so sure of himself it's probably best just to let him believe that rather than correct his scientific fallacies..... and besides it's Taco Time here in La Paz, MX... I'm out of here

[Tellie]

Oh brother. You could possible weld a prop shaft to a bicycle rig and push your boat around a marina as well. You'd be the only one but I suppose it could be done, but why.

[Tellie]

Originally Posted by SV THIRD DAY

Two comments I've never heard cruisers make.

1. I have too much solar on my boat.
2. My water maker makes too much water per hour

Of course the converse of those statements is commonly disgusted in cockpits around the anchorage's of the world

And I would be one on point #2.
You know I love you man, but I can do 125gallons per hour on 1500Watts and still charge your batteries all with a Honda2000eu. I assure you that is too much water for a lot of simple cruisers.