12v raw water pump ideas

[Cheechako]

Originally Posted by Islander53

I appreciate the advice . But in 6 years of cruising around I have had at least 10 incidents with my belt driven jabsco 1673-1001.
I have 2 brand new spares in boxes, and rebuild parts. This pump has proven to be unreliable, and difficult to access , and not really enough water.
3 100 amp alternators will give me about 100 amps at idle. They cost $65 each on Amazon and have proven reliable. I use my 50 hp engine mostly as a generator. If I could fit 4 alternators I would. My engine has 3 pulleys on the crank and I intend to make as much power as I can without having to convert to a serpentine belt.

My main question for me is how this will be wired. Looking at the schematic or the 5 pin normally off relay I am confused how It will work. I think I need a normally on relay. I can use the power from the buzzer to kill the pump. Does that make sense?

Well, that's strange. I think in 40 years of sailing I've had to replace an impeller twice, mostly my own fault. (although I have replaced more just for maintenance) I have never in that time had to do more than that, which is probably lucky. I have probably replaced a half dozen electric water pumps, removed or replaced 3 wash down pumps.

Why not just buy another quality belt driven, mount it separately from the abandoned one on the engine? The nice thing about belt drive is no electrics/wires (which seem to be a problem on boats sooner or later), it is self adjusting it's rpm to the engine speed for cooling and water flow. If you have an electric problem, lightening strike etc, if the engine's running it doesn't care.

One wonders if a centrifugal pump works for cooling, why they don't put them on engines instead of impellers?

[Islander53]

So at idle right now I filled a 5 gallon bucket in 51 seconds, so say 6 gpm at idle. The pump I believe is rated at 12 gpm .

So I'll be 3x the water at idle with the 17 gpm electric pump.

How does someone calculate these requirements?

[Islander53]

Ok let's say I ditch the electric pump idea, and I want to upgrade my belt driven pump to a larger one with more flow, how do I ensure the new pump will not provide too much water at idle?

Currently I can get quite a bit of steam if I push my engine too hard . It is over propped , and I have increased the amount of fuel on the governor , I watch my egt when running hard and I understand the limitations of my engine and the consequences of high exhaust temps . But I would like to increase my water flow to try and reduce steam. More than anything it's embarrassing.

Running this configuration has allowed me enough reserve power for bar crossing and similar situations where extra power is needed short term
. My boat is more 40 tons loaded and my engine is an isuzu c240 "60hp"

This set up is working well for me , especially when I had the auto prop on , with the fix blade I can get a true .5 gallon per hr at 4 knots. And about 2 gallons hr at 6.5 knots.
Although I will repower with something around 100 hp when I melt the isuzu.

[a64pilot]

Originally Posted by Cheechako

One wonders if a centrifugal pump works for cooling, why they don't put them on engines instead of impellers?

Of course centrifugal pumps work for cooling, the fresh water pump is centrifugal, and until the day comes, which can often be decades that the seal begins to leak, they require no maintenance at all.

I feel sure the reason they are not used on the raw water side is that the pump is desired to be mounted on the engine and a centrifugal pump must be below water line, and many times the raw water pump on an engine isn’t, so the pump would drive engine positioning and of course that’s not going to happen, so they use a rubber impeller pump so that it will work even if above water line.

So why doesn’t an outboard use a centrifugal pump? Not sure, but assume it’s size, cause a centrifugal pump on an outboard would require no maintenance, and I’d assume that would be a selling point?

[techmans]

My concern with the electrically driven raw water pump would be that in a SHTF scenario where you lose electrical power, be it total or local ( flooded bilge?),to the pump you will also be dead in the water because your engine cooling falls away.
You thus forfeit one of the advantages of a diesel in that it can operate without electricity.Proceed at your own risk.
This happened to me in a powerboat that I inherited with the purchase of a marina.The raw water was supplied by an electric pump.After hitting an underwater obstacle the propeller sliced the plywood bottom of the boat causing the pump to be submerged.Even though the inflow could be stemmed with a T-shirt and handled by the bilge pump, I still had some drive at idle despite the drive line damage. However, engine cooling was lost and I was dead in the water.

[RaymondR]

If your engine has a thermostat the amount of water flow through the engine is governed by the thermostat rather than the pump.

There is usually a small orifice which allows water to bypass the thermostat when it is completely closed. This allows an amount of water to continue to cool the exhaust hose.

[model 10]

If you didn't mind the pump cycling all the time, a temp switch at the heat exchanger would turn the pump on when needed. I wouldn't trust a horn relay (as shown above) for something this important. I wouldn't even trust an electric motor for this unless it was industrial.

[Mike Banks]

Wire it through the hold-in circuit for the injector pump--put another relay in there. When the diesel starts, the pump will also run.

Why not simply drive it via a fan belt? That worked fine for mine--and is more reliable than an electric pump.

[Rorzech]

At truck parts stores the have all kinds of 12 volt waterproof cube relays that will run anything.

[Taipe]

An electric motor to drive the raw water pump puts your engine at great risk of too much flow in proportion to engine rpm, resulting in water backing up into the combustion chambers via the exhaust elbow to exhaust valves. I don't know why you want extra alternators, but consider other options such as having a machine shop make a balanced (marine alloy) aluminum double grooved pulley to bolt on to the engine crankshaft pulley. This will provide the option of two belts to a higher output alternator without the tight tension required from a single belt. This will allow the water pump(s) to be driven from the stock engine pulley at the correct flow in proportion to engine rpm as originally intended.

[JimsCAL]

Another thing to consider is to select a pump designed for continous service. Msny are not, and will fail if asked to run for several hours without stopping.

[kev_rm]

"I installed three aftermarket alternators"

"I have problems with my belt driven raw water pump"

Surely no correlation there.

Originally Posted by Islander53

I appreciate the advice . But in 6 years of cruising around I have had at least 10 incidents with my belt driven jabsco 1673-1001.
I have 2 brand new spares in boxes, and rebuild parts. This pump has proven to be unreliable, and difficult to access , and not really enough water.
3 100 amp alternators will give me about 100 amps at idle. They cost $65 each on Amazon and have proven reliable. I use my 50 hp engine mostly as a generator. If I could fit 4 alternators I would. My engine has 3 pulleys on the crank and I intend to make as much power as I can without having to convert to a serpentine belt.

My main question for me is how this will be wired. Looking at the schematic or the 5 pin normally off relay I am confused how It will work. I think I need a normally on relay. I can use the power from the buzzer to kill the pump. Does that make sense?

[RaymondR]

Originally Posted by Taipe

An electric motor to drive the raw water pump puts your engine at great risk of too much flow in proportion to engine rpm, resulting in water backing up into the combustion chambers via the exhaust elbow to exhaust valves. I don't know why you want extra alternators, but consider other options such as having a machine shop make a balanced (marine alloy) aluminum double grooved pulley to bolt on to the engine crankshaft pulley. This will provide the option of two belts to a higher output alternator without the tight tension required from a single belt. This will allow the water pump(s) to be driven from the stock engine pulley at the correct flow in proportion to engine rpm as originally intended.

As someone who has actually used an electric driven impeller pump on an engine cooling system I can unequivocally state that provided the electrics are installed so that the pump is stopped whilst the engine is not running there is no problem with flooding the engine.

In the first instance I used the electric pump on occasions when the belt driven pump failed. I manually switched the pump in this instance.

For the second I used the low oil warning circuit to switch the pump as derailed in an earlier post.

[Islander53]

Well.. it's all said and done. It does not appear like there is too much flow at idle. Tho I estimate I have my idle set at 1000 -1100 rpm . I idled the engine for a half hour without it exploding. Maybe I'm in the clear. Good watetflow compared to the belt driven pump.

So I appreciate all the advice. For the people who question why the hell modify perfectly good systems. Because I can . My engine already has a a tripple belt crank pulley. 100 amp 1 wire alt cost $65 shipped in 1 day from Amazon. . So for less than $200 I can charge 120-150 amps at idle . At about 1500 rpm above I can produce 210 -300 amps short term. Carry 3 spares, and if one goes down it doesn't affect the whole system .And for me it makes sense. When I want to cook, I fire up the engine and can easily power any electrical cooking device at idle .or run a mini split heater/ air conditioner. . I also piped my coolant throughout the boat with a series of radiant heaters. Essentially my main is my generator. I have all the time in the world to modify and try to reinvent the wheel, but only have a limited amount of money. So the game is how can I improve my sailing lifestyle using the least amount of money.

[a64pilot]

Originally Posted by RaymondR

If your engine has a thermostat the amount of water flow through the engine is governed by the thermostat rather than the pump.

There is usually a small orifice which allows water to bypass the thermostat when it is completely closed. This allows an amount of water to continue to cool the exhaust hose.

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.