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Old 04-03-2018, 12:19   #16
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Re: Proposed human cycle powered watermaker

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Originally Posted by owly View Post

Help me out with wattage numbers.

One watt = 0.00134102 hp
The most efficient 12v watermakers use 17amps at 12v, roughly 200 watts. According to wikipedia an average person can sustain 100 watts on a bike, a pro athlete 300watts. Watermakers don't like to stop and start, they take 10 minutes of running to produce good water, and then need 10 litres of fresh water to flush so you need to be able to pedal non stop for a few hours while sailing a boat. Not easy. Probably simpler to onnect an alternator or generator to the bike and charge the batteries in a burst over a few days then run a 12v watermaker.
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Old 04-03-2018, 12:19   #17
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Re: Proposed human cycle powered watermaker

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" That 360 pounds of water is "
Roughly eight pounds per gallon, that's sixteen pounds of water per day per person. And in hot conditions with exertion, that may need to double. But's let's say 16#, and of course there are at least two people on board to keep proper legal watch. 32# per day now. 360# of water is under a two week supply, not allowing for any delays or breakdown. And it will take up the space of roughly one 55-gallon drum.
Considering most recreational sailboats (over 90%) are 28' OAL or shorter...better to load up on the freeze-dried water, it is way lighter and more compact to stow. (Commonly sold at outfitters in the Adirondacks, honest. In #10 tins.)
8.4 pounds per gallon actually.......... I've seen dehydrated water before, in fact it's easy to make your own, but I've never found a good way to rehydrate it.... ;-)
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Old 04-03-2018, 12:26   #18
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Re: Proposed human cycle powered watermaker

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The most efficient 12v watermakers use 17amps at 12v, roughly 200 watts..
I forget to mention that will produce 60 litres per hour (divide by 4 if you must work in American units).

Or you could sit in the shade beneath a few hundred watts of solar panels. Thats what I do.
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Old 04-03-2018, 12:29   #19
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Re: Proposed human cycle powered watermaker

Interesting idea.
Seen a number of boats with portable stepper exercising equipment. Might be an easier solution as it can be easier stored when not in use.

Still, when I sit in winter on my recumbent bike mounted on a training wheel I could easily see that in a boat in calm weather.

If you install this, always have enough tank capacity available to make it half way over the longest distance to port.
If an issue arises, simply turn towards your closest port.
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Old 04-03-2018, 12:51   #20
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Re: Proposed human cycle powered watermaker

I meant this
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Just adapt the ones designed for manual use
For the "optional exercise" part.

Obviously you need sufficient water available without depending on this science project.
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Old 04-03-2018, 13:01   #21
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Re: Proposed human cycle powered watermaker

There are a number of old threads that might be helpful:
Pedal Powered Watermaker
Turn calories into electricity?
My Quest for Water - Engineering build on a RO system

I didn't do an extensive search, so there may be more, but there has been and still is interest in this topic.
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Old 04-03-2018, 13:20   #22
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Re: Proposed human cycle powered watermaker

Fundamentally the problem with a pedal powered water maker is that it is a water maker. If you are going to have a pedal power anything you might as well just use it to charge the batteries, then instead of a single use device you have a multi-tool for the same weight and space. Then of course install a 12V water maker.

You would give up some efficiency theoretically, but would probably greatly extend the life of the water make since the batteries can act as buffer between output and draw.
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Old 04-03-2018, 13:41   #23
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Re: Proposed human cycle powered watermaker

There are huge efficiency losses between the physical work - electricity generation - storage - back to physical work.

To the point where direct is marginally practical, via electricity not at all.

https://youtu.be/S4O5voOCqAQ
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Old 04-03-2018, 13:51   #24
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Re: Proposed human cycle powered watermaker

The general idea of human effort providing needed resources for the boat and exercise as a side benefit is a good one. The specific idea of powering a water maker is too focused and limited.

Using human effort to generate electricity would be better. The electricity could be used for any number of purposes: navigation lights, cooking food, watermaker, fans, propulsion, electronics.

Most efficient would generating electricity at the same time as it is used.

At 100w effort for 1hr you would get about 8amp-hr energy.

Im guessing it would take about 15min at 100w to boil a cup of water to make rice with using s microwave.
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Old 04-03-2018, 14:34   #25
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Re: Proposed human cycle powered watermaker

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All that you say is valid........... but misses the point altogether, which is that one can kill two birds with one stone here. You need exercise, and you need water. Nothing feels as useless as working out on something that has no function other than burning energy. Gym equipment seems to be the norm. I've never used exercise equipment for the above reason. I hike, bicycle, walk, split wood, stack hay, etc.
Have you ever done an ocean crossing? You might change your mind about exercise equipment, or at least understand why no one has it.

Quote:
Normal calculation is half a gallon of water per person per day. A Pacific or Atlantic
This is about right it can be slightly less.
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crossing can easily run 30 days. 15 gallons would be reasonable for one person if nothing went wrong, and you got rain and could collect it efficiently. 20 would be more
Not 15 gallons "and" you collect rain. It is 15 gallons, or you collect rain for a 30 day passage.
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realistic including a safety margin, and that would be 168 pounds plus the container(s). Let's say 180 pounds. Two people aboard, and you have 360.
I have done several crossings including 4 passages that were more than 4000 miles. I never carried more than 15 gallons, even on a passage without rain.

On one passage I set off with 5 gallons on a 50 day passage and arrived with 10 gallons.
Quote:
Considering that fuel, batteries solar and other chargers, charge controllers, bedding, clothing & weather gear">foul weather gear, a dinghy and perhaps a motor, spare materials cordage, parts, blocks, tools, computers, nav gear, pots and pans, and countless other odds
You basically don't need any of those things, and I only have about half of them, but I have more than 1000lbs of other stuff.
Quote:
and ends contribute to consuming the 1800 lbs or 2600 lbs of payload for the two boats, the amount of payload left for food and water is rapidly reduced. That 360 pounds of water is 360 pounds of something else you can't carry......... perhaps the bicycle(s).
The weight of water is never really considered by 99% of cruisers. Food and water is a relatively small fraction of the total weight of the boat, typically <5% often around 2%. I can only think of one case actually discussing it, and it was a trimaran.
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Weight in a multihull is critical...... I'm a pilot and a backpacker, so I'm hyper sensitive to weight. A multihull that is overloaded will pound the bridge deck, I want to basically live on the bridge deck a good share of the time.......

H.W.
If you are overloaded with extra water setting off, on a long passage, it's not so bad, after a week or two... It's normal.

Also, you really cannot rely on a watermaker. If it fails (and they often do) you could be in trouble. Maybe you can justify it for things like showers that you can do without, but recycling shower water with a filter saves 90% of water, so you should tackle that first.

Typically water makers are not so much for passages, but for convenience living at anchor. In this case you can use your pedal power already for bicycle, or powering the dingy.

A more realistic way to save weight for water would be to make a solar still. These are far more reliable than any water maker. Theoretically it's possible to make 12 gallons a day on 10 square feet, so even with a basic solar still you can make 1 or 2 liters.


I still support your pedal powered water maker idea, but be sure to research it properly to ensure maximum output for the effort. The spectra watermakers are far more efficient than typical homemade ones, by up to 4x. A lot of people don't care they just burn more fuel, but if you are pedaling you will care more.
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Old 04-03-2018, 14:45   #26
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Re: Proposed human cycle powered watermaker

@John

Impressive video.

Aside that, esthetically sometimes more muscles seem to make men less sexy ;-)
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Old 04-03-2018, 15:18   #27
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Re: Proposed human cycle powered watermaker

Unfortunately this thread has degenerated with negativity and contemptuous comments to the point that it is not worth replying to anymore. There seem to be a fair number of these types in every crowd who instead of looking for solutions, are only content to ridicule and heap scorn, imply ignorance, and stupidity. Constructive and useful comments are in the minority as usual. I've been designing and building equipment for various purposes for many years.... basically a lifetime. If I'd listened to the nay sayers, I would have sat in front of the TV like a vegetable instead of doing things. I can only assume that some folks here are projecting their own incompetence and poor judgment, and assuming that it is universal.
This is exactly the sort of thing I do. I have been building and repairing things since I was a child and I'm 62. It's how I make my living. It starts out with an idea, then progresses to some basic reading to determine feasibility, then serious research, and finally to the design phase and then construction. If I were as ignorant and foolish as some people seem to be suggesting, I wouldn't have made it past 20, much less to retirement age. Every internet forum seems to have these kinds of people. Fortunately my community and my customer base seem to be different. They bring me challenges, because they know I'll solve them, and that's paid my way nearly all my life.

There really isn't any more to say, accept to thank those few who have provided positive input.

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Old 04-03-2018, 15:27   #28
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Re: Proposed human cycle powered watermaker

Hey, don't be put off by some tire kickers.
There where quite a few valid thoughts in the thread.

Go, if you are convinced it will work, do it and proof that its a good idea.

Very interested to see the results!
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Old 04-03-2018, 15:35   #29
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Re: Proposed human cycle powered watermaker

Two things . . . . (1) there have been a number of human powered electrical generators designed and built (and attempted to be sold), based on the same basic theory (spare time, desire for exercise, 'green'). Google should turn them up. You might want to reach out and see if they would share their learning with you. And (2) Team NZ used bike power to drive their hydraulics in the most recent America's cup (using world class athletes), and at least one of the recent French solo round the world G-Class Trimarans has a bike on board to drive sail handling (interesting did not to drive the water maker). Again, both might well share their learning if you reached out in a polite fashion.
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Old 04-03-2018, 15:53   #30
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Re: Proposed human cycle powered watermaker

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Originally Posted by swampbush View Post
The most efficient 12v watermakers use 17amps at 12v, roughly 200 watts. According to wikipedia an average person can sustain 100 watts on a bike, a pro athlete 300watts. Watermakers don't like to stop and start, they take 10 minutes of running to produce good water, and then need 10 litres of fresh water to flush so you need to be able to pedal non stop for a few hours while sailing a boat. Not easy. Probably simpler to onnect an alternator or generator to the bike and charge the batteries in a burst over a few days then run a 12v watermaker.
Actually the most energy efficent 12V watermaker known is a Spectra Cape Horn Extreme with one pump running 7-8amp/hr. roughly 85 to 100 Watts
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