SailNet Community banner
1 - 13 of 13 Posts

·
Registered
Joined
·
483 Posts
Discussion Starter · #1 ·
The bilge on our boat collects water from rain down the sailtrack, nothing serious but it does fill up one isolated bilge compartment when we get a good soaking. I have a Jabsco belt driven diaphragm pump that works well, but it is not automatic and hose is not mounted in the bilge, it is free to move from one bilge compartment to another if needed. So after a good rain I go out to the boat and hold the hose in the filled compartment while I hold the manual switch for the pump. A couple of minutes and its done. I was thinking it would be nice to have a small automatic Rule pump to handle this pump out, but I could not figure out how to add another hose to the above the water line thru hull without having to worry about water coming back down another path. Then I thought, if the Jabsco is not running then water should just flow thru it. I tried that with a hose and sure enough it works. So, I should be able to leave a small automatic Rule pump in this bilge and connect its output to the existing input line to the Jabsco. When it collects water the Rule will kick on and pump the water out thru the Jabsco pump to the thru-hull. And when (if? hopefully never) I need the higher capacity Jabsco in another compartment I can just disconnect that line from the Rule pump and run the Jabsco as usual. Anyone see a problem with this?

thanks,
Ron
 

·
Registered
Joined
·
1,654 Posts
Could you put a check valve after the first pump? Then the water can't run into the first pump.
Better would be a check valve after each pump
DO NOT install any check valves with a centrifugal pump like the Rule. The back pressure will be too much for the pump to overcome. They can move a lot of water but without much force. The electrical analogy is high voltage, low amperage.
 

·
Registered
Joined
·
5,252 Posts
I think you mean low voltage, high amperage Sabreman.

Centrifugal pumps like the Rule are very different from positive displacement pumps like the diaphragm. Positive displacement pumps try to move the same flowrate regardless of the resistance. The discharge flowrate of centrifugal pumps is reduced as the discharge pressure increases. The diaphragm pump already includes check valves - at the inlet and outlet. I doubt the Rule would have much success trying to overcome the resistance of the pump and its valves. A tee in the discharge and a check valve in the Rule line between the pump discharge and the tee might work. No need for a check valve in the diaphragm pump iine as the pump valves will prevent backflow.
 

·
Registered
Joined
·
483 Posts
Discussion Starter · #6 ·
Ok, Thanks.

I was wondering about check valves, but was not sure how many were needed, but it makes sense that the Jabsco has an output check valve already. It looks like the Rule needs a separate line anyway. The specs indicate that the discharge line needs to be continuously running upwards from the pump and check valves are NOT recommended. Also, it it not really automatic, it runs every couple of minutes to see if it meets resistance rather than senses water level. Maybe I will hook up a water witch switch to the Jabsco and anchor the hose in the bilge instead.

Ron
 

·
Registered
Joined
·
794 Posts
It's easier to fix the leak...Most masts have sail tracks but if you fill the track below the boom with silicone and make a mast boot out of a tire inner-tube and large hose clips the leak usually stops. Mine did and my masthead is 76 ft off the water which a a lot of sail track!
 

·
Registered
Joined
·
2,525 Posts
I just reworked the bilge system in our boat. It has a very weird bilge, essentially 2 feet of 3" pipe buried in the concrete of the aft keel section.

I have a large manual diaphragm pump with 1-1/2" pick up hose and a foot valve stuffed down there. I also have a whale diaphragm pump, electrical, with 3/4" pick up hose and a foot valve stuffed down there. The two pumps connect through a T on their discharge side, then out to the through hull via 1-1/2" discharge hose.

I've yet to get a sensor or a controller for the Whale pump. Gotta figure that out yet.
 

·
Registered
Joined
·
483 Posts
Discussion Starter · #9 ·
York,
You probably are right. I have a mast boot so the leak is pretty much limited to the track. If someone made a rubber 'thingy' that plugged the sail track that would be convenient. I don't like the idea of silicone, but it really only needs to be just above the boot, to let the water exit before entering the boat. I should give it a try.

thanks,
Ron
 

·
Registered
Joined
·
1,654 Posts
"I think you mean low voltage, high amperage Sabreman."

You are correct..... This is embarrassing.... I'm an electrical engineer. Granted, it's a specialty in computer systems, but still embarrassing. Ironically, after study, my failure was in properly understanding water flow, of all things. But when you're wrong, you're wrong. Live and learn, that's SailNet.

Still, don't use a check valve on a Rule pump. Learned that the hard way. Use a vented loop. Fail safe.
 

·
Registered
Joined
·
5,252 Posts
"I think you mean low voltage, high amperage Sabreman."

You are correct..... This is embarrassing.... I'm an electrical engineer. Granted, it's a specialty in computer systems, but still embarrassing. Ironically, after study, my failure was in properly understanding water flow, of all things. But when you're wrong, you're wrong. Live and learn, that's SailNet.

Still, don't use a check valve on a Rule pump. Learned that the hard way. Use a vented loop. Fail safe.
And as a mechanical engineer, I would sometimes use electrical analogies to explain water flow to students. I always found this practice by EEs and MEs amusing.
 

·
Registered
Joined
·
193 Posts
CapRon,

I'm quite surprised the rule would pump thru the jabisco and the check valve downstream of it. As mentioned the regular centrifugal bilge pumps do not generate a lot of pressure. When you say "small" rule are you saying 2000+ gpm or less than 1000 gpm?

Sabre, sometimes check valves are necessary but selection is very important.
In my case, my discharge port is just below the toerail. For a vented loop to work it has to be above the discharge.
Without some sort of check valve the water will run back down the hose and back to the bilge. With an automatic pump this will cause unnecessary cycling and eventually drain the battery (been there, done that)

McMaster has a check valves with cracking pressures as low as .3 psi (less than 1ft head) I've used them for years. Of course, right now I'm fighting the bilge pump in my "new to me" boat that has a swing gate check and only a 500 gph pump. That's just not big enough to pump thru the check, thru roughly 12' of hose and up 4-5' out of the boat. I get either a small trickle or nothing out of the pump.

Time to go shopping.

John
 
1 - 13 of 13 Posts
Top