Home built watermaker

[Owly055]

On long passages, a watermaker could be as real asset as a SUPPLEMENTAL supply along with tankage, bottled water, and rain capture.   Weeks to months of sailing is going to leave one with weakened legs due to no real way to exercise.   I've thought a great deal about building a simple pedal powered water maker.  Watermakers are actually really simple..... a pump, really a pressure washer pump feeds seawater through a filter system, and the filters are readily available and not particularly expensive in the context of what they are.   I can see having a pedal powered system where you pump the pedals while sitting in the cockpit, the pump connected to the filter system by a flexible high pressure hose.   While they do make emergency hand pumped watermakers, the output is pathetic, and you can deliver far more power with your legs than you can with a hand pump.  There are a number of articles about building your own watermaker, but I have yet to see a pedal powered unit.   Electrical controls and motors are failure points and depend entirely on your charging system to operate.    I've never seen fitness equipment in a small sailboat, but it makes sense to me.   I'm visualizing a two cycle operation.  The first pumps seawater through a prefilter system to remove the junk, plankton, etc into a tank.   The second cycle pushes it at  high pressure through the RO filter to remove the salt.  The pump would be a multi piston pressure washer pump.  In stage one, all 3 pistons would be pumping.   In stage 2, two pistons would be disabled.  There are several ways this could be done... I've had numerous of these pumps apart, and they are extremely simple.  The simplest might be two pumps, one of which would bypass in the high pressure cycle.   

         Just another of my mad ideas..........  The difference between my mad ideas and those of most folks, is that I often build things and they usually work .....  Some folks watch TV, I invent things in my rather extensive shop.

                                                                                          H.W.

[ralay]

I don't think it's mad.  If you Google "pedal powered reverse osmosis" there are youtube videos and info on plans. 

I think the challenging part is figuring out how to mount it so you can use it easily while also storing it.  If we had a big, flat shantyboat, I'd definitely build a full size bike dynapod.  On our sailboat, there are really limited places to mount a crankset even if we used an existing seat.  And for Ocean use, I think it would be really difficult to use unless it was dead calm.  I'm usually using my feet to brace myself all the time.  You'd probably need to sit with your back to the low side and pedal up and you might still need a lap belt.  It would be really easy to hurt your knees if you weren't pedaling with good ergonomics.  We also rarely have a lot of extra energy.  If you're planning on singlehanding across oceans, you may be exhausted by your regular daily workload and he more interested in having the sun or wind provide your power.  That said, it would be awesome at anchor.  And if would be awesome under way if you could get a secure, comfortable fit and had the energy to run it.  Take pictures if you make one.

[Owly055]

I don't think it's mad.  If you Google "pedal powered reverse osmosis" there are youtube videos and info on plans. 

I think the challenging part is figuring out how to mount it so you can use it easily while also storing it.  If we had a big, flat shantyboat, I'd definitely build a full size bike dynapod.  On our sailboat, there are really limited places to mount a crankset even if we used an existing seat.  And for Ocean use, I think it would be really difficult to use unless it was dead calm.  I'm usually using my feet to brace myself all the time.  You'd probably need to sit with your back to the low side and pedal up and you might still need a lap belt.  It would be really easy to hurt your knees if you weren't pedaling with good ergonomics.  We also rarely have a lot of extra energy.  If you're planning on singlehanding across oceans, you may be exhausted by your regular daily workload and he more interested in having the sun or wind provide your power.  That said, it would be awesome at anchor.  And if would be awesome under way if you could get a secure, comfortable fit and had the energy to run it.  Take pictures if you make one.

     You probably are right about the impracticality, but with wind vane steering, there isn't a lot to do on a long passage except tack every few hours or half a day if you're in the trades, except when the weather gets changeable.   I suspect there are solutions to all the problems where there is ingenuity.    I walk a minimum of 2 miles a day in the woods and fields near where I live in almost any weather.  It would be nice to be able to maintain fitness on a long passage.   I don't see that the daily workload on a junk rigged boat would amount to a great deal.  You aren't clambering forward constantly, fighting with sails, changing them and reefing them one handed while hanging on for dear life with the other.   Mostly the exhaustion one would have to deal with is due to the odd sleep schedule.

                                                              H.W.