Electric genset raw water alternative to march

[svHyLyte]

Originally Posted by emcmia

I have a catamaran with 3 air conditioners, one 400 gpd RO system and a 5
kw genset, all of which utilize AC powered raw water pumps. To minimize spares, I standardized the inventory with March and Cal submersible/mag-drive pumps, nominally 900 gph, each with the power cable fitted with a standard AC plug connected to a dedicated AC supply or the genset output.

If the genset shuts down due to grass in the strainer, I can immediately cool and restart the genset (after cleaning the strainer) by temporarily plugging the the pump into an electrical outlet powered by my inverter.

In 12 years, I've only had one failure (CalPump) after 1100 genset running hours. All are below waterline and none of the pumps are submerged.

emcmia--

Your experience has been exceptional so good for you. And, it may have to do with the size pumps you have been using as 900 GPH is quite a bit larger than what one commonly sees used for air conditioning systems aboard, which are often in the 360 GPH size range. Accordingly, your pumps may not have to work so hard and so remain relatively cool. Our boats have lived in a small southwest Florida marina, 55 boats, for the last 24 years where most all the yachts are fitted with A/C and we have seen the failures of Cal Pumps repeatedly due to differential expansion between the metal casing covers and the plastic facings because the pumps get quite hot when run continuously without the cooling effects of immersion. Being air cooled, the March pumps tend to last quite a bit longer and quite long with preventative maintenance.

N'any case, different ships, different long-splices. One makes one's choices and lives with the results, eh?

[a64pilot]

What PM can you do to a March pump?

[emcmia]

Originally Posted by a64pilot

Be careful pumping water thru an engine that is not running.
Many if not most you can fill the exhaust and this will flood the motor with water thru an open exhaust valve, which can hydro lock it at least and can bend a rod and or corrode they cylinder

Engine shuts down due to hi-temp sensor sensing no water flow. Temporary, albeit short duration sw pump op cools sensor permitting immediate engine restart. Obviously, if engine doesnt immediately start, there is another issue to resolve, obviating continuous pump op.

[emcmia]

Originally Posted by a64pilot

What PM can you do to a March pump?

None that I’m aware of.
Each of mine have operated between 500 and 1000 hrs to date without problems.

[svHyLyte]

Originally Posted by a64pilot

What PM can you do to a March pump?

As previously noted:

Originally Posted by svHyLyte

For longevity, March pumps need to be oiled with 3-in-1 oil every few months or so. There are little oil galleries above the carrier bearings on either end of the drive motor and a couple of squirts of oil is all it takes.

FWIW...

With the foregoing and periodic back flushing of debris from the raw water circuit, our March MDX pump has been running for 12 years without complaint.

[Simi 60]

Originally Posted by emcmia

Engine shuts down due to hi-temp sensor sensing no water flow. .

Maybe you should install the under $20 temp alarm with probe connected to exhaust elbow.

Ours in sub tropical water runs at 31c and the alarm is set for 45c.
It gives you a warning waaaaaay before it gets to emergency shut down stage.
Actual engine temp hasnt even increased at this stage.

http://www.cruisersforum.com/forums/...rm-202270.html

[a64pilot]

There are several March pumps, mine look like this guy, I assume it can’t be oiled?

[Lepke]

A friend just bought one of these on ebay for a small generator. Stainless steel, probably made in China. $89, inc. shipping. 5 gl/min. Made for home brewing. US 120v. Seems to do the job at full electrical load. 3 cyl. diesel.
https://www.ebay.com/itm/Magnetic-Dr...ater+pump.TRS0

[svHyLyte]

The pump we have is this:


The MDX 5/8--115v pushing 6 GPM up to 7 feet of head. We purchased ours from Depco Pump for $135.00 in 2006 to replace one originally installed in 1996 and virtually never serviced by the prior owner. I oil ours with 3-in-1 oil on the last weekend of every quarter and it runs quietly and without complaint at least four days a week for cooling in the summer months and heat in the winter. These daze the pumps go for something int the range of $190 to $210.

FWIW...

[svHyLyte]

Originally Posted by a64pilot

There are several March pumps, mine look like this guy, I assume it can’t be oiled?Attachment 173540

I believe the brown plastic shroud can be pulled for access to the drive motor and oil galleries. Look carefully. The oil galleries are situated on either end of the drive motor case, above the bearing races, and would be "on top" if the drive were sitting horizontal on it's mounting feet. FWIW I added a little dab of white paint next to the oil gallery openings so they are easier to spot when the pump is in a relatively dark, awkward, location as is ours.

FWIW...

[a64pilot]

Pretty sure that brown case is solid, I think. You can get into the pump, but I don’t think the motor.
Just a different design pump is all. However they do usually last more than 5 years on boats in a Marina that run the AC pretty much continuously.
I always used to leave my AC in dehumidify mode 24/7 when we were gone.

[Simi 60]

Originally Posted by svHyLyte

. These daze the pumps go for something int the range of $190 to $210.

FWIW...

$270 + $255 in freight for Australia

[Simi 60]

Originally Posted by Lepke

A friend just bought one of these on ebay for a small generator. Stainless steel, probably made in China. $89, inc. shipping.

$121 + $90 in freight for Australia, though another supplier sells them here for $102 to my door.

Looked at them but thought the flow was borderline.

[Sailmonkey]

Originally Posted by svHyLyte

I believe the brown plastic shroud can be pulled for access to the drive motor and oil galleries. Look carefully. The oil galleries are situated on either end of the drive motor case, above the bearing races, and would be "on top" if the drive were sitting horizontal on it's mounting feet. FWIW I added a little dab of white paint next to the oil gallery openings so they are easier to spot when the pump is in a relatively dark, awkward, location as is ours.

FWIW...

The brown plastic is not a shroud, the motor is encapsulated and water cooled. No motor maintenance is possible. However the pump is submersible.

[kenbo]

Originally Posted by a64pilot

Where you connect your boats power to the generator itself is where I wired into. On mine there is a terminal block, yours may have an electrical box, but somewhere the generator wiring ends, and the boats begins.
I did it there so that anytime the generator is making power, the pump is running. My generator comes online right about when it hits full RPM, so a two or three sec delay before the pump kicks in, so there is a very few seconds of running with no water, you can hear the water flow when it begins, there is a distinct change in exhaust.
Also when you turn the generator off, the pump quits, but the engine is still spinning down and this blows the water out of the exhaust on mine, so the exhaust is dry.
You also can’t fill the exhaust from cranking the engine, no matter how long you crank it, cause the pump stays off until the generator comes online.
The only new failure possible that I can think of is if your engine is running but your generator isn’t making power, then it would burn up your exhaust if you let it keep running, but on mine, there is no mistaking the difference in sound when there is no water flow.
Same thing as if your impeller pump failed on a standard installation.

Hey 64pilot, I always wanted to ask you about your genset raw water pump. I think it's a great idea but there is a failure mode that worries me. What happens if the generator end fails, there's no AC to power the pump but the engine is still running. Is there a system to shut down the engine before it overheats?