Engine Driven Watermaker HP Pump

[SV THIRD DAY]

Originally Posted by Celestialsailor

It has never made sense to me to generate 110VAC to drive an AC motor, to drive a HPP. If I had a diesel gen set, then I could see it. But to have something like a Honda generator ($1100) and then a watermaker and the introduction of active gas while cruising does not appeal to me. .

It really all depends on how you operate and set-up your boat. You've seen enough different styles of boats and approaches to cruising down there in La Paz to know that what works for some doesn't for others. My wife and I could not live comfortably aboard rationing water and not having a fresh water rinsedown for our deck gear and SCUBA gear. We showered in the heat of the Mexican summers twice a day and that promoted "romance aboard" if you know what I mean... For cruisers with a diesel genset that plan on running the genset 2-3 times per week for battery charging, it's a relative easy decision to make large amounts of water during that generator run time and when you consider a 20GPH for $4200 or a 30GPH for $5000, you would be paying thousands more for a comporable 12v system. Basically buying energy efficiency that you don't need.

It's the folks without a deisel genset that I think have to wrestle with the question of adding a Honda 2000 generator to their boat, not just to power the water maker but as a way to keep their batteries charged. At $949 with free shipping from www.mayberrys.com it's one of the best Boat Units I think I spent in outfitting my boat, without it we would have needed to run our diesel engine daily to keep our batteries charged, which is crazy to do at anchor. What led us to design the 20 and 30 GPH water maker to run off of the Honda was seeing them on the decks of boat everywhere in the anchorages during our time in Mexico. I started off the cruise with an engine driven unit, but the way we used our boat it just didn't make sense for us. We stayed in anchorages for weeks rather than days, so we didn't move around a lot where I could make water "for free" while underway. Away from the marina shore power most cruisers were like us and couldn't keep up with their daily power demands off of wind and solar and the Honda gave us a way to keep our batteries properly charged. We already carry gas aboard for our outboard engine, dive compressor, etc. and since the Honda can run for 5 hours on a single gallon of gas, we simply added one 5gal gas can to our deck fuel carrying rack. So we look at a 5 Gallon jug of gas as either 500 gallons of water or 750 gallons depending on the 20 or 30GPH unit that use the same amount of power. (1100W or 9.3A 120v AC)

So our routine was to make water 2-3 times a week using our Honda keeping our tanks topped off while putting 30A DC into our battery bank at the same time. Because the hourly produciton was so high, we didn't need to make water daily and put extra demands on our 12v battery bank. If the Honda was to die, get stolen, or fall overboard, we can run the water maker through our 2000W inverter when we are motoring with our alternator putting out Amps. When we were at anchor, we used the Honda to make water and charge batteries, but when we were underway we powered the water maker through our inverter and let the alternator supply the power.

There isn't a "right vs. wrong" way to go here it's all about how you set-up and run your boat at the end of the day in the 12v vs. 120v AC decision tree. If you go with the 12v option, I think it's a "no brainer" to go with the Spectra system over village marina, etc. Once you go down the 12v branch of the decision tree then the big thing becomes gals/Amp and Spectra rules the 12v world on that front! Our friends with Specrta units loved them and I always knew when they were making water at anchor because I could see their engine running...going back to that 12v power shortage thing.

[a64pilot]

If you mount anything to the hull of the boat and want to belt drive it off the engine, make sure you idler is the self tensioning, spring loaded type. That will allow the small belt length changes while keeping belt tension the same.

[Cheechako]

Now I remember, the Refrig pump didnt have an idler.. it had a big hinged base under the pump, the correct belt length kept it hinged up off the base and a spring tensioned it... although the weight of the pump pretty much did that on it's own! haha, pretty rube goldberg... but it worked well in that instance... The electric motor on my band saw is setup the same way... weight of the motor tensions the belt..

[Celestialsailor]

I remember a while back the police cars use to have a 110ACV units on their engine. I thought this would be a cool way to go if I could find one to replace my alternator. Then use it to power an AC HRO and the 3 step onboard battery charger.