Possible engine driven watermaker or washdown option?

[SailingFan]

I have a Hunter 27 with a Yanmar YSE8 inboard, and also an 8HP Johnson long shaft outboard kicker, and am considering adding a few things to include a washdown pump and perhaps a watermaker.

What has me considering this is that there is a double pulley on the front of the Yanmar, and it begs the question of what could be done with the second pulley, as the alternator belt is the only one being used and the water pump is driven internally on my engine.

I therefore have a second belt pulley available to drive...something.

I am wondering if anyone has used it to power a washdown pump, or better yet, a watermaker, using the engine's extra pulley to drive the pump to reach the 800 PSI required to filter seawater through the membrane of all the watermakers I have found to date online. If I recall, the household units for land use do not reach sufficient pressure to get the brine to separate from the raw water, but given sufficient pressure, could a belt driven pump do it assuming 8 hp engine as a driver plus whatever belt/gear reduction I could assemble?

Is such a concept workable (surely someone has tried it), and if so, what are the costs of such a modification/addition in the case of the wash pump (assuming just a basic low pressure pump and hoses there) or the watermaker?

I assume requirement for a membrane (plus its housing) and filtration housings for taste/sediment filters, a potable water holding tank, high pressure lines, and an inlet seacock. I am considering sharing the cooling water intake, or possibly retasking the one for the head, and using my onboard 36 gallon aluminum tank for the head supply and installing that new freshwater tank anyway for potable water) and an over-side drain for the brine?

So what do you think, are these two worthwhile projects if attempted in this manner?

[Panope]

Greetings, SailingFan.

Sorry, but I have no experience or advice concerning your pump question.

However, I am fascinated that you have both inboard and outboard powerplants of the exact same rated horsepower. Never seen that before. Can you tell us how these powerplants compare in terms of speed, ability to punch into weather, vibration, sound, and fuel economy?

Thank you, and sorry for the thread drift.

Steve

[Tellie]

At first thought you would think this is a workable project. But there are good reasons why the majority of watermaker companies don't make engine driven water makers. Amplified vibration alone on a small 8hp diesel would most likely be unacceptable.

[Lepke]

There are people selling watermakers that use an engine driven pump. One I have seen on this site. I have a Perkins 4108 generator engine I am planning to ad a watermaker pump on the front pulley. Most pumps use a double belt. 900 psi in salt water, 100 in fresh to make water. Also ebay has belt driven kits.

[HopCar]

Another good use for that spare belt would be to drive an emergency bilge pump. Jabsco makes some good sized belt driven pumps with clutches.

[SV THIRD DAY]

The engine belt driven water maker is known in the water maker industry as the Siren Song of DIY Water Makers. The sweet song of "free water" while motoring has sucked in many cruisers to only have their hopes smashed on the rocks of reality. Now we do sell engine/pulley driven water makers, but ONLY after I do my best to try and talk the person out of it.....why.

1. It's the hardest water maker installation to get right. If the pump is not mounted on the engine correctly you will (not if but WILL) damage your pump, clutch or engine. To do the mounting right and make the bracket right, isn't something a guy with no fabrication experience and a harbor freight welder can pull off. I know...I see them broken all the time.

2. The Water isn't "Free" when you are sitting in an anchorage (where most cruisers spend over 90% of their time) and have to run the single most expensive and maintenance prone piece of cruising gear on your boat (the ships main engine) to make water.

3. You can buy a 120v AC power washer for $80 that will easily run off of your inverter or the trusty Honda 2000 generator...don't use your $1500 high pressure water maker pump for that. You will be working your pressure relief valve every time you pull the trigger because the positive displacement pump HAS to pump water when spinning...the water must exit the pump, so when you are not spraying water, it flow out of your relief valve. But water maker relief valves are really only made as emergency pressure reliefs and not continuous open/close devices.

In my opinion as someone who makes, sells and services water makers I recommend either a 12v DC energy recovery like a Spectra or a simple AC direct coupled piston pump for those with a diesel generator or Honda 2000 to power it. But leave the main engine for moving your boat.

[SailingFan]

Thanks for the rapid replies, everyone!

Panope, there is actually an interesting story behind it, but in essential terms, the inboard was not running when I purchased this boat in Daytona Beach, Florida, and the PO had used the outboard to move the vessel from his purchase location in St. Augustine to Daytona via the ICW. I simply utilized the same outboard to move her from Daytona back north through St. Augustine, to Jacksonville, then into the St. John's River, and from that juncture, back south to Palatka, where she is currently moored.

It was quite the trip I can assure you, as the running rigging was all missing, and though I had sails, I had no way to hoist them. Sailing the ICW would have been less than fun anyway. Motoring was the only way to go for most of it in that section as it turned out.

In any case, I have yet to get the inboard running, due to what turned out to be a broken valve spring, something I am still attempting to locate (seems out of state folks refuse to sell them into Florida - something about Yanmar's dealer licensing I guess). If anyone has a lead or a couple spares, I am likely interested!

As far as an 8 HP outboard on this vessel, however, I can offer some insight after that trip.

First, you get lots of cavitation at higher throttle. The prop and foot were clean, but cavitation was common in ANY wave over perhaps a couple feet. If you get low to the bottom, you pull up sand/mud and cavitate as well, surely not good for the water pump.

This outboard motor gives the 7000 plus pound displacement Hunter 27 between 4 and 5 kts. at full throttle, measured via multiple GPS devices. Theoretical hull speed for a 22.5 foot waterline is only about 6-7 kts., by my math, so I am not sure if it is reasonable to expect more from only 8 HP in a cavitation situation and currents (as the GPS measures speed over land, not over water that is moving against or with you). If I had the option, I would opt for higher HP (perhaps a 20?) and use it at lower throttle, because I think speed would have been higher, and noise and fuel consumption would have been less with the 20 at a lower throttle setting.

Second, an outboard sips fuel at this HP level (relative to the 200 HP I once had on a 23 ft. Scorpion), and is danged convenient to not have to keep turning around to steer the outboard (like on my jon boat), just using the Bonus' tiller was perfectly acceptable in all but the tightest quarters at headway speed leaving the outboard aimed forward. Now in tight quarters, the direct steering of the outboard was far superior, and I could pivot Bonus on her fin in the St. Augustine marina we visited for an overnight.

This was good because we had to thread our way between many a million-dollar yacht in there (the same scary issue was in Daytona as well, as it was Speed Week, and the drivers were there with their massive vessels in droves). The damage that would have been caused by an impact with one of those exceeded the price I paid for Bonus, so that would have been pretty upsetting on all sides. The snag is that it is a little tricky to steer with the outboard tiller cocked up against the transom because of the proximity of the powerhead to the stern.

Another situation I noticed is that the outboard, as it is mounted outside the transom, does not add to the clutter of the cockpit, but the fuel cell sitting on the lazerette and the associated fuel line is a pain.

I will likely install an overboard vented tank someplace that will hold gasoline and a transfer line aft, because I like the idea of having access to multiple forms of propulsion, especially given my experience with the inboard to date. The Yanmar is reputed to have parts availability all over the planet, but here in the good old US of A, in a state surrounded by salt water, no less, I cannot seem to locate valve springs. Just sayin'...

[SailingFan]

I have seen the watermaker kits now that have engine pulleys running them (found some today online), but I had something less "proper" in mind. I do see your points, SV, et al., and think I am going to have to resign to carrying bottled water while I sort out this forward tank issue. The forward tank would be easier to replace but for that it is installed permanently, and I would have to cut away the V berth sole to get it free. Too bad, too, because it is aluminim, and looks to be original 1978 vintage. Corrosion surely exists within it. Not sure how to get it cleared out.

I wonder if anyone has ever attempted to get a bladder and install it within the original tank, or if that would just cause chafe on the bladder with a resultant leaky mess with which they still must deal... Maybe a regular household filtration system on the tank water is the answer, I don't know.... Ideas?

[SailingFan]

Originally Posted by HopCar

Another good use for that spare belt would be to drive an emergency bilge pump. Jabsco makes some good sized belt driven pumps with clutches.

That is a pretty good idea, I will have to check into that. I had not considered a belt driven bilge pump.

I was also considering if there was a way to power a winch with it, but am less than certain of the safety of doing so. Dangly things (like ropes) that can get into gears and pulleys make me nervous. However, if one could use the extra belt to power a winch that does not allow the dangly bits near the pulleys...???

[SV THIRD DAY]

If you send me an email at Rich@CruiseROWater.com I will be happy to send you a Manual for the Engine Driven water maker if you want to review in detail.

[SailingFan]

Could an anchor windlass be powered using the extra pulley? Or is that just begging for trouble?

Never mind, I can just see how that would go... Better to install a real one on the bow...

Save

[Cheechako]

I converted an AC watermaker unit to use on my Yanmar as an engine drive unit. It worked great. You need an electric clutch for your pump so it's not running all the time. You need a pressure relief valve so you can set it at max psi....just in case! A quality hand needle valve is nice to creep up on your pressure. A good quality gauge.

[roverhi]

Did someone report that Yanmar GM series engines do not like large sideloads on the front pulley??? Seem to remember someone saying not to bolt on large alternators because of possible front crank bearing issues. Might want to do more research before you make use of that extra pulley groove. Part time loads like a wash down pump or emergency bilge pump probably wouldn't be an issue but refrigeration, water maker, or other long duration loads could be a problem if there is a front crank bearing issue.

[Cheechako]

Originally Posted by roverhi

Did someone report that Yanmar GM series engines do not like large sideloads on the front pulley??? Seem to remember someone saying not to bolt on large alternators because of possible front crank bearing issues. Might want to do more research before you make use of that extra pulley groove. Part time loads like a wash down pump or emergency bilge pump probably wouldn't be an issue but refrigeration, water maker, or other long duration loads could be a problem if there is a front crank bearing issue.

His isn't a GM, but it's a good point. I found the watermaker pump (Cat, 25 gal/hr) had not near as much effect on the engine rpm as an alternator. So I imagine the loads are minimal. I didn't really need to tighten the belt much. The electric clutch was maybe... oh... 8" diameter, which is a pretty easy ratio on the engine.

[MikeTC]

My L380 3YM30s had an engine driven WM on when I purchased it. The pump was isn't mounted to the engine and the permanent noise annoyed me, so I now only put the belt on when using it. I find it works well and find you don't want to make water in anchorages anyway. If motoring I consider topping up tanks. One downside was the HP hose failed in engine bay resulting in salt water sprayed over engine.