PDA

View Full Version : Dual Bilge Pumps



RedDog
03-18-2004, 12:48 PM
New thread to keep from walking over Brad's specific question on "best pumps."

I have been considering adding a second pump but also struggling how to plumb in the second one without a second thru-hull fitting. I think I have figured it out and it is simpler than I was initially thinking. Add loops in the discharge lines at a point higher than the thru-hull fitting and before the tee that connects the 2 lines. A rough (and I mean rough) sketch is attached. My online reasearch says to NOT use check valves like I had initially thought would be needed. The high loops eliminate the need for check valves. Also, as Ed mentioned in Brad's thread, the backflow at pump shutoff provides a cleaning effect to the pump intake. Additionally, at least 1 manufacturer recommends not using check valves due to the low pumping capacity having trouble opening the valve.

Unless I hear of a better approach, I intend to have have the wiring as follows. Pump 1 will be connected to the boat wiring harness such that is works either automatically or from the dash switch regardless of which battery the selector switch is set to. The second pump will be hard-wired to the second battery and will only work automatically but will work even if the battery selector switch is set to off.

bverd
03-18-2004, 01:54 PM
Now you got me thinking I need two... it never ends (LOL).

--bverd

MOP
03-18-2004, 02:03 PM
Tim like I said in the email that will work but only if you move the through fitting down, must be down about 15 inches the loops alone will not do it 1/2 the water will come out the second pump.

Rodger
03-18-2004, 02:37 PM
I have 2 pumps discharge through one fitting. I plumbed the 2nd pump into the original discharge hose just before the outlet at the transom. I made a tee that angles the line from the 2nd pump toward the discharge hole. It works fine and no noticable water goes back through the other pump. I can also run both pumps simultaneously.

MOP
03-18-2004, 03:37 PM
I have 2 pumps discharge through one fitting. I plumbed the 2nd pump into the original discharge hose just before the outlet at the transom. I made a tee that angles the line from the 2nd pump toward the discharge hole. It works fine and no noticable water goes back through the other pump. I can also run both pumps simultaneously.

What pumps are you running, and do you have a good rise in the hoses?

Rodger
03-18-2004, 04:31 PM
My main pump is something like a 1500 gph and it is located in the original factory position a couple feet in front of the transom. The hose from the main pump rises an inch or two above the height of the discharge outlet just prior to the outlet. The discharge is near the top of the transom. It's right on the down slope just prior to the oulet that I installed my custom tee. The secondary pump which is only about a 400 gph unit is mounted in the bildge just in front on the transom. The tee it discharges into is angled pretty steep toward the transom only a couple inches from the outlet. The pumps are just your basic Rule centrifugal units.

gcarter
03-18-2004, 06:20 PM
As I've mentioned before, this is the first trailable boat I've owned. My Minx (and I know otrher models do also) have a female garden hose connection on the port transom, up high. What is this fitting for? On mine it is not attached to anything. If it is not to be used, it could be a pump discharge. Right?

George

Digger
03-18-2004, 06:33 PM
female connector high on the transom?

Was probably meant to be for a through hull flush adaptor.

MOP
03-18-2004, 06:54 PM
Rodger sounds real interesting I will have to give it a try, all I have ever tried was off the shelf T's and Y's. The acute angle thing sounds fool proof, we install a few check vavles and extra pumps each season most get the extra through hull but some don't want them so we go to check valves. Check valves a Ok but do need some checking and cleaning so your trick will be tried first on my 22 then at the shop. Thanks!

Phil

RickR
03-18-2004, 06:55 PM
gcarter
Female hose connection is for flushing engine.

MOP
03-18-2004, 07:00 PM
As I've mentioned before, this is the first trailable boat I've owned. My Minx (and I know otrher models do also) have a female garden hose connection on the port transom, up high. What is this fitting for? On mine it is not attached to anything. If it is not to be used, it could be a pump discharge. Right?

George

You may want to keep it for flushing and try rodgers sharp angle connector for the second pump.

Phil

GEOO
03-18-2004, 07:59 PM
Just install two check valves (one way valves). Then the water can't back through to the other pump.
I run two pumps, two through hull fittings. The one through hull sound's like a nice idea. One of my pumps is a Rule automatic pump. The other is a remote mount pump which can run dry. I have this pump hooked up to a hose with a skimmer type pick-up, (it can suck the bilge dry!!) Before I had this pump the salt water used to be 1-2" deep and splash all around.

MOP
03-18-2004, 08:30 PM
George now you have me thinking about a remote pump with a WC bottom sucker end, I have a brandy new diaphram pump with a bad pressure switch I replaced under warentee and they did not want it back so it found a new home. To many ideas and now snow! Crap I was out raking the yard in my T shirt last week now back to shoveling and salting!

GEOO
03-18-2004, 08:37 PM
MOP U R the new quick draw on the site....
How or what or which.... direction is your project going??? :cistineb:

P,S. I have the same engine for the past 4 years, just drop the cr (10:1 to 8.5:1) and changed the intercooler. I have a few extra pulleys too....

cigarette30
03-18-2004, 10:58 PM
I am a little confused as to the reluctancy of two thru hull's, other than maybe the appearance (which doesn't look bad, chrome side by side). In order to have true flow capability, and redundancy, I have two entirely separate pumps, hoses, fused circuits, and discharges. I have had this on all previous Donzi Classic's, even prior to my Cigarette (which offers this setup as a standard). Currently, on my 04 22' Classic, the factory installed a Rule 3700, and a Rule 1500. They were unable to install both 3500's, due to the height, as they would not clear the oil pan. After almost losing an 18', due to an exhast leak, I think it's worth it, if for no other reason, the piece of mind. Thanks. The boat is scheduled to be picked up tomorrow, and I hope to post pictures very shortly

Rich
03-20-2004, 09:21 AM
Two pumps with seperate smooth wall hoses and thru hulls is the way to go. Absolutely no check valves. The primary pump should be as small as you can get with a small diameter hose. The small diameter hose will keep the amount of water that comes back into the bilge when the pump turns off to a minimum. Mount this pump as low as possible. Wire this through the dash mounted switch.
The secondary (or backup) pump should be considerably larger and mounted a couple of inches higher. You don't want the secondary pump coming on or in the bilge water under normal circumstances. This way the second pump will only be used in an emergency and should then last virtually forever. This pump should also be an automatic model wired directly to a second deep cycle battery so it can't be accidently turned off. A bilge pump alarm on the second pump is also a good idea. If you've got that serious a leak that pump #1 can't keep up with, the second pump will come on and sound the alarm. Without the alarm, you may not know of the problem, the pumps will run until the battery(s) are dead and the boat will deep six.
If the boat is docked or moored, someone nearby may hear the alarm and investigate. They will then see your name and phone number you conveniently have on the windshield (or elsewhere) and call you. Hopefully.
Sounds like a lot of work, but beats salvaging your pride and joy from the bottom.

RedDog
03-20-2004, 10:21 AM
Rich - great input. Guess I have a long ways to go to get this right. Fortunately I haven't started yet