12v raw water pump ideas

[Taipe]

[QUOTE=Captain Bill;2958157]I don't think that I would be terribly concerned about the flow rate through the heat exchanger provided that your fresh water side thermostat is working properly. You would need to size the output of the pump to match the requirements at max power.


Exactly, there should be no concern about too much flow thru the heat exchanger. But, an electric water pump is going to compound his problem by potentially feeding too much return flow into the exhaust elbow that could backup into the exhaust manifold. But, I am wondering why he is having problems with his Jabsco raw water pumps. Maybe he has it mounted as a pedestal pump and has an alignment problem? Or maybe seaweed, barnacles, etc are getting past his water filter. I had that problem with my original filter and replaced it with a large translucent bronze Groco w/monel screen mounted near the kingston cock and the second is a small ss filter Jabsco on the suction side of the raw water pump.

[Islander53]

There has always been issue with alignment and belt issues . But the problem with the pump seemed to be water intrusion into the bearing, then the pump becoming seized. The same problem happened multiple times rebuilt and new pump. once they start leaking a little bit then if not run for a couple weeks the bearing is shot . Maybe the misalignment was killing the seal and bearings? I could have easily tried a different model pump and see if results differed. . But this was a getting two birds stoned situation, get rid of my problem pump and make room for my 3rd alternator.
I will certainly report back when the first failure happens. Tho I have confidence the Groco centrifugal pump will last , they have a 15000 hr brush life and they are built for continuous duty. Time will tell.

[RaymondR]

Originally Posted by a64pilot

No, there is no thermostat in the raw water side, raw water flow is controlled by engine speed, it’s the same flow rate whether the engine is hot or cold.
The thermostat is on the fresh water coolant side.

It’s just like a car really, just the raw water takes the place of the airflow over the radiator.

Of course. Since both of my previous engines were raw water cooled my mind is stuck in that system.

[Lepke]

In the old days, fishermen that wanted to run a number of auxiliary belt drives installed a shaft alongside the engine, mounted on 2 pillow block bearings. The shaft was run off the crank with a belt system powerful enough to run all the devices. Then the alternators, pumps, etc., were run from the shaft using their regular belts. Now they use hydraulics.
I think with a centrifugal sea water pump that is not always flooded by being below the water line, will eventually fail to provide cooling to the engine. Probably at a critical time. And you'll probably have marine buildups on an impeller that isn't flexible.
I don't know the hp draw of your alternators, but on a dyno, I've seen that alts can draw 25 hp. X3 maybe more than your sailboat engine provides. Maybe you should look into a heavy duty engine that has many power takeoff points.

[Islander53]

I have the pump installed about 4 feet below the waterline, lots of pressure feeding the pump. It's working good and after 3 hrs of idling it still has hasn't filled up the exhaust . Water spits out just fine. Think I'm in the clear.

. Have no idea how much hp the alternators draw, but I am consistently putting in 120 amps at idle about 1100 rpm . I put 2 of the alternator leads going straight to the inverter terminals about 4' away. For the first time today I was able to weld using the full 200 amps of my welder thru the inverter. Before I installed the 3rd alternator and put the 2 alternator leads directly to the inverter , I had a limit of around 120 amp on the welder before the inverter would trip. I welded off and on today for about an hour welding some 3/8" stainless with the welder maxed out and the engine at a little above idle. I can't see the amp meter while I'm welding so I don't actually know what I was drawing. But the math says 398 amps at the inverter to weld 200 DC on the welder ..

Anyways 3 shitty alternators might not be for everyone. But $200 for the alternators and $400 for the "power jack 32000 watt inverter" (it says 32000 watts 12vdc but it's just a lie) it's really a 4500 watt continuous/12000 watt surge . split phase 240v / 120v inverter/charger

So $600 and I've essentially turned my 60hp Isuzu into a fairly capable, inverter generator.
Who knows how long all the cheap Chinese stuff will last but I'm sure to find out.

[Compass790]

Originally Posted by Islander53

I have the pump installed about 4 feet below the waterline, lots of pressure feeding the pump. It's working good and after 3 hrs of idling it still has hasn't filled up the exhaust . Water spits out just fine. Think I'm in the clear.

. Have no idea how much hp the alternators draw, but I am consistently putting in 120 amps at idle about 1100 rpm . I put 2 of the alternator leads going straight to the inverter terminals about 4' away. For the first time today I was able to weld using the full 200 amps of my welder thru the inverter. Before I installed the 3rd alternator and put the 2 alternator leads directly to the inverter , I had a limit of around 120 amp on the welder before the inverter would trip. I welded off and on today for about an hour welding some 3/8" stainless with the welder maxed out and the engine at a little above idle. I can't see the amp meter while I'm welding so I don't actually know what I was drawing. But the math says 398 amps at the inverter to weld 200 DC on the welder ..

Anyways 3 shitty alternators might not be for everyone. But $200 for the alternators and $400 for the "power jack 32000 watt inverter" (it says 32000 watts 12vdc but it's just a lie) it's really a 4500 watt continuous/12000 watt surge . split phase 240v / 120v inverter/charger

So $600 and I've essentially turned my 60hp Isuzu into a fairly capable, inverter generator.
Who knows how long all the cheap Chinese stuff will last but I'm sure to find out.

I like the way you are thinking
Was wondering myself about replacing the mechanical oil pump with an electric one but now you have shown it's possible for the water pump as well if needed.
Didn't end up going down the electric road for the oil pump as figured out a way to make it work.
Hope you stay lucky with the cheap chinese electronics.

[RaymondR]

Originally Posted by Lepke

In the old days, fishermen that wanted to run a number of auxiliary belt drives installed a shaft alongside the engine, mounted on 2 pillow block bearings. The shaft was run off the crank with a belt system powerful enough to run all the devices. Then the alternators, pumps, etc., were run from the shaft using their regular belts.

A boat came into the yard where I fitted out my first boat with a lay shaft arrangement as you describe. However, rather than a pillow block it had an AC motor on one end of the shaft and a clutch on the other. When at sea the shaft was driven by the engine and when shore power was available by the electric motor.

[sdj]

Originally Posted by Islander53

I am trying replace my belt driven raw water pump with a 12 v one to make some room on the engine for another alternator (yes I want 3 alternators!) I have nothing but problems with my belt driven jabsco pump and this seems like a good solution .

I have been mulling over this same problem for some time.

Firstly, it's about $3k for a 6KVA 24 alternator. That's ONE alternator. See the delco remy 55si. This is a brushless fire engine alternator!

You could use a centrifugal pump for cooling, but it won't self prime - if you were happy with that.

You could use an electric jabsco pump - but how much of the extra alternator capacity did you just take, and did you gain anything?

My approach always is to simplify and add redundancy. That means fit the proper device for the job, and add a spare if a failure will break things.

[Islander53]

I figured I lost 10 amps by using the groco centrifugal pump. I've looked at the remi 55si and some of the systems like mobile power . If i was using a serpentine belt I would certainly be using one very high power source. Instead of 3 . But my situation was I already have a tripple pulley on the crankshaft. And if I can keep all 3 belts aligned and running smooth then I've added quite a bit of redundancy, the coolant water pump also has 3 pulleys so I will probably never encounter a situation where I've lost coolant flow thru the engine , or a lack of charging power. in the event the groco fails , my exhaust temp alarm will go off , and in 5 mins I can replace my 12v raw water pump with a spare.

[model 10]

Wondering where are you guy's are getting the mounts for the pumps and extra alternators? Are you designing/building them yourselves?

[sdj]

Originally Posted by Islander53

I have had numerous bearing and mechanical seal failures, I rebuilt the pump at least 3 times

The problem is too much shaft loading from all those overly tight belts. That will destroy bearings and seals.

[Islander53]

I buy the alternator belt adjustment brackets. (Just the slot) on Amazon or eBay for around $10. Then fabricate the rest of the mount.... Most of the reason I wanted 3 alternators was for running my welder , so I can build alternator brackets... Maybe I should add one more .

[Diesel Bill]

The boat I have now has a 7.5 KW Onan Generator with a belt driven rubber impeller to push sea water through the heat exchanger. The pump housing was trashed when I bought the boat. Rather than spending money on an unreliable pump, I plumbed up the March 120 volt, 8 GPM centrifugal pump from the A.C. Its wired up so when the gen is started the pump is energized. Been working good for over 3 years.

[model 10]

Originally Posted by Islander53

I buy the alternator belt adjustment brackets. (Just the slot) on Amazon or eBay for around $10. Then fabricate the rest of the mount.... Most of the reason I wanted 3 alternators was for running my welder , so I can build alternator brackets... Maybe I should add one more .

How would you do that if your welder was 3000 miles away? Maybe a wood mock up?

[Islander53]

I have no doubt that my new 12v raw water pump set up is as reliable as a belt driven. Some didn't agree , but belts fail all the time. And relays fail all the time.. I personally really like the idea of a centrifugal style pump.