Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 19-08-2019, 18:42   #16
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

I have hard time believing the water pressure could over come the exhaust pressure. I also have my idle set on the high side cause my transmission likes it like that way.

So the relay shown above will work? I am having a mind block on how the 5 pin relay will engage when the ground is removed

Power goes from ignition key run position to the relay . Power from relay to the pump, ground from ignition circuit goes to relay. Then the 2 connections to the oil pressure switch.
Then the pump is grounded to ignition circuit?
Islander53 is offline   Reply With Quote
Old 19-08-2019, 18:44   #17
Registered User
 
Captain Bill's Avatar

Join Date: Apr 2008
Location: Punta Gorda, Fl
Boat: Endeavourcat Sailcat 44
Posts: 3,173
Re: 12v raw water pump ideas

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. That being said my primary concern would be that at low power settings the engine would not be producing enough exhaust to empty the elbow and muffler.



As for turning it on, Yanmar's have a dual ported adapter for the oil pressure switch so that it can accommodate both the idiot light switch and an oil pressure gauge sender. The standard configuration is delivered with only the idiot light switch leaving the other port free. You didn't say the brand of engine, but perhaps yours is set up the same way. If you put a normally open pressure switch in the second port you could use it to run a relay to handle the high amps of the motor.
Captain Bill is offline   Reply With Quote
Old 19-08-2019, 18:47   #18
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
Re: 12v raw water pump ideas

Definitely do not restrict the flow to the suck side of a centrifugal pump, I doubt it would cavitate as they can’t pull much vacuum at all, but it could make it lose prime, and that is at least annoying.
You may also want to install an exhaust temp alarm, it would tell you if you lose water flow well before the hose and muffler are damaged.
On my boat where the exhaust is and with the dinghy making almost an echo chamber, you hear the instant you lose water flow, it gets loud.
a64pilot is offline   Reply With Quote
Old 19-08-2019, 18:54   #19
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

The engine is an Isuzu c240 mechanical injection. Nothing electrical on the engine
The low oil pressure sender is a single wire system that uses the block as a ground to complete the buzzer on circuit . Then as the oil pressure builds it breaks the ground turning off the buzzer.

Can someone clarify how this would be wired. I am having a hard time
Islander53 is offline   Reply With Quote
Old 19-08-2019, 19:13   #20
Registered User
 
wingssail's Avatar

Join Date: Jan 2010
Location: On Vessel WINGS, wherever there's an ocean, currently in Mexico
Boat: Serendipity 43
Posts: 5,508
Send a message via AIM to wingssail Send a message via Skype™ to wingssail
Re: 12v raw water pump ideas

Honestly, I'm not sure why you don't solve the problem of the standard issue water pump. Mostly these pumps go for many years. You also avoid all the problems of lack of flow or too much flow that a switch or relay can cause.

Your leading query of "cheap" makes me think you are looking for a way to avoid fixing the standard belt driven pump and I am really wondering why you think you need three alternators?

Face up to it and fix the original problem. THEN buy a spare, if you think it is unreliable.

But in all cases, avoid another gadget to fix a problem you shouldn't have in the first place.

SIMPLICITY!
__________________
These lines upon my face tell you the story of who I am but these stories don't mean anything
when you've got no one to tell them to Fred Roswold Wings https://wingssail.blogspot.com/
wingssail is offline   Reply With Quote
Old 19-08-2019, 19:41   #21
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

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?
Islander53 is offline   Reply With Quote
Old 19-08-2019, 21:32   #22
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

I've got the relay sorted out and ordered.. I have an exhaust temp alarm incase the relay proves unreliable..


Soooo how will I know if I have too much water flow and not enough exhaust? Do I just wait till the motor hydraulics ?? Is this a genuine concern? Does anyone have real info on a situation where a boat had too much water flow at idle and caused damage?
Islander53 is offline   Reply With Quote
Old 19-08-2019, 21:52   #23
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

Another thought.

The centrifugal pump I planned on using is 17 gpm but only 9 psi, so this may work to my advantage . Shouldn't a 2" exhaust on a 50hp 4cyl be producing more than 9 psi of exhaust pressure? ..I had originally been concerned about using such a low psi pump thinking that it wouldn't be able to Inject at mixing elbow but I think I tested that by removing the raw water hose while running and if anything the mixing elbow pulls a vacuum.
Islander53 is offline   Reply With Quote
Old 20-08-2019, 01:14   #24
Registered User

Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,432
Images: 7
Re: 12v raw water pump ideas

I fitted keel cooling to my last boat using the engine driven pump as the circulation pump. In order provide water to the exhaust system I fitted a small 12V electric impeller pump. To power it I used the accessory terminal on the ignition switch through the normally closed terminals of a double throw relay. The coil was powered from the oil pressure switch.

When the ignition switch was turned on the NC terminals would attempt to power the pump on. However since the oil pressure warning switch is on the relay pulls out. Immediately the oil pressure rises and the oil pressure switch switches of and the relay coil de-energizes allowing the NC terminals to close and the pump switches on.

When you shut the engine down the oil pressure signal pulls the NC terminals open shutting off the pump.

Turning the ignition off isolates the power from the pump.

Takes a bit of gerring your head around but it worked well for the three years I had the boat.
RaymondR is offline   Reply With Quote
Old 20-08-2019, 07:42   #25
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
12v raw water pump ideas

Quote:
Originally Posted by Islander53 View Post
Another thought.



The centrifugal pump I planned on using is 17 gpm but only 9 psi, so this may work to my advantage . Shouldn't a 2" exhaust on a 50hp 4cyl be producing more than 9 psi of exhaust pressure? ..I had originally been concerned about using such a low psi pump thinking that it wouldn't be able to Inject at mixing elbow but I think I tested that by removing the raw water hose while running and if anything the mixing elbow pulls a vacuum.


The exhaust back pressure is very low, less than 1 PSI. However the water will cause back pressure, how much I don’t know, but certainly well less than 9 PSI.

Your dinghy, when it’s tight as a drum is only 3 PSI
a64pilot is offline   Reply With Quote
Old 20-08-2019, 08:00   #26
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,483
Re: 12v raw water pump ideas

I thought about using an electric pump on a couple of 12V diesel generators I built. I worry too much about reliability to do so. I dont think I can remember a boat I bought in 45 years that didn't have one pump that was bad.... Water pump, bilge pump, washdown pump .... something.
It's good you are installing an alarm either for water flow or a heat alarm on the exhaust elbow if you do it.
You are going from a dirt simple system, that controls it's own flow, to one with multiple failure possibilities.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 20-08-2019, 08:20   #27
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
12v raw water pump ideas

However it can be simple, if you source a NO open oil pressure switch and automotive relays are very reliable, think of how many you have chafed on your car, I’ve never had to replace a single one myself and there are several on a car from the fuel pump to usually electric windows, door locks, horn etc.
A mechanically operated ball valve operated from the throttle cable and a pump. The pump would be I believe the most likely point of failure, so get a good one.
It’s going to take some rigging to do of course, and my opinion is that multiple alternators isn’t what you want, cause to begin with I suspect that they are all internally regulated.
I suspect the best course of action would be to fit a large frame alternator that is externally regulated.

The magnetically coupled air conditioner water pumps run for likely tens of thousands of hours between failure, they are extremely reliable, but I only know of 120 or 220 VAC ones, surely there is a DC one?
a64pilot is offline   Reply With Quote
Old 20-08-2019, 08:54   #28
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

I was actually thinking this was going to be more reliable.
The groco centrifugal pump is rated for 15000 hrs brush life and continuous duty.

Belt tension and alignment are one issue that goes away
For me the water pump is the first belt that goes on. So changing a pump requires removing 2 other alternator belts first. And access to the pump mount and belt tension is a major pain.
It takes me about an hour to remove and reinstall the water pump... And they only fail when you are entering a narrow bar crossing.

I have had numerous bearing and mechanical seal failures, I rebuilt the pump at least 3 times , then thought maybe I was rebuilding them incorrectly because they kept failing. So I bought a brand new pump. A year later it started leaking out of the front seal, then the bearing goes . Never once had an impellor fail.


The MAIN reason for me is to make room on the engine for a 3rd alternator. I use my engine as low budget generator. And works great for my needs. I have a 5000 watt inverter and have been trying to stop using propane. I'm using electric frying pans, toaster oven, induction cook tops . And so far it seems pretty efficient . With 2 alternators at idle I put in 70-80 amps , so I idle the engine while I cook unless it's sunny. I have 1300 watts of solar and 2 d400s (which do nothing) and 20 gc2 golf cart batteries.

I have looked into higher output and better regulated alternators and generators but am limited to what a small v belt can handle.
For me 3 cheap 100 amp 1 wire alternators each on their own belt seems reliable and simple. It supplies a lot of current when needed for cooking or starting air conditioning. And I do not count on the alternator for the full charge cycle just to supplement high power draw for short time. Turning the key is a lot easier than pulling a Honda generator. And my main goal is to consolidate to one fuel source. Diesel. Now I need a 25 hp diesel outboard and I could actually do it
Islander53 is offline   Reply With Quote
Old 20-08-2019, 09:04   #29
Registered User

Join Date: Apr 2017
Posts: 116
Re: 12v raw water pump ideas

After lots of research I'm confident the relay will be dead simple and reliable. The groco pump claims to be very reliable.
So that part of seems fine.

My only concern is now the too much water flow at idle and I'm not sure how I can verify this without just doing it and waiting for something bad to happen .

Say water makes it to the manifold, as the exhaust valve is open it's shooting out high pressure gas so water can't enter? Then it's closed so water can't enter
Can water really enter through the exhaust of a running engine?
Islander53 is offline   Reply With Quote
Old 20-08-2019, 11:07   #30
Moderator Emeritus
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Jacksonville/ out cruising
Boat: Island Packet 38
Posts: 31,351
12v raw water pump ideas

Quote:
Originally Posted by Islander53 View Post

Can water really enter through the exhaust of a running engine?


I don’t think it would have to, if it got to the really hot exhaust valve something bad is going to happen relatively quickly.
You could bleed off water from the pressure side of the pump and return it to the suck side too as a way to regulate water flow, and I assume you could also slow it down electrically, but that’s beyond me.

I bet that water ingestion is the number one killer of small marine Diesels, and it almost always comes in from the exhaust.
a64pilot is offline   Reply With Quote
Reply

Tags
pump, raw water, raw water pump, water

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Quick Raw Water Pump Sea Water Seal Replacement belizesailor Engines and Propulsion Systems 31 09-08-2022 19:23
Raw Water Pump Temperature as a Proxy for Sea Water Cooling Flow Dockhead Engines and Propulsion Systems 16 19-09-2015 10:45
Raw Water Pump vs Fresh Water Pump Cheechako Engines and Propulsion Systems 44 01-02-2012 14:31
Electric Centrifugal Raw Water Pump 12V Sagittaire Engines and Propulsion Systems 20 22-06-2011 23:13

Advertise Here


All times are GMT -7. The time now is 21:46.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.