Originally Posted by Curious Sailor
There is one more compartment forward under the berth, so essentially three areas for water collection. I'm trying to visualize the hook up you describe, but I don't think it's coming together correctly in my head. Do you happen to have photos of the set-up? I'm curious to see the vent set up.
I had imagined two bilge pumps with two independent outflow through hulls above the water line. then possibly inserting a 1" pipe drain tubes in the forward stringers to allow water to flow back to the bilges.
Thanks for your advice on this! It's very much appreciated!
How many pumps do you run in your 44?
First off, I have not seen a vented loop used for two bilge pumps before but I think it would work. You would have two of them, one for each discharge hose put before a Tee where they would combine the outlet leg of the hose to go to the thru-hull, which normally for bilge pumps would be above the water line.
Here is a description and diagram of other uses though:
Vented loops and anti-siphon valves ; how they work on boats
Here is another from Forespar:
There are other brands. But the vented caps can sometimes stick so you are supposed to inspect them regularly and make sure they still work. You can even make you own vented loop with a bronze or PVC Tee and put a hose on the upper side instead of a flapper valve. That is common, and even ones that the Forespar may be modified to take the flapper off and put a small hose clamped there and lead it down to the bilge. It should normally not have any fluid in it but it keeps a siphon from being developed at the loop. You can Google
vented loops and find lots of examples. The ready made ones are nice because they have a nice radius which is better through put without sharp bends.
boat has an abnormal setup. There are two diaphragm
pumps, both above the bilge. There is one pickup hose to the bilge (for bilge water) that goes to a three-way valve which is connected to another three-way valve on one side, and to the "main" bilge pump. The other pump goes to a second three-way valve which goes to a pickup in a gray-water tank and the other side of the valve goes to the other valve, so both valves are connected. The outputs of both pumps share a thru-hull and there are two check-valves in each of those hoses so that one pump does not pump back in to the bilge or gray-water tank. A diagram is below.
There is also a small bilge pump to take any water that gets in the bow chain locker and it outputs to the bilge where it goes out with the other bilge water (if any).
It is what came on the boat. I do not like the check valves because (a) they can stick open if not kept clean and (b) they don't close 100% all the time allowing some leakage. There are ones that close 100% but they jam easier. So it is a compromise. The system is good in that each pump can pump out the bilge or the gray-water by changing the three way valves. It is a bit complicated which was the theme of the PO. I am going through and simplifying as many things as I can but will leave this as is for now. I redid everything though and put in new hoses, relocated the pumps to shorten hoses and get rid of kinks and bends. I also put in new water sensors for the bilge and a separate alarm
circuit that is higher than the bilge water level sensor to activate the pump. If I use the gray-water pump I have to turn it on at the panel after I set the valves correctly.
I am having trouble uploading the PDF of my diagram. I'll try another way.
(It is too big for the forum upload limits and I don't know how to shrink a PDF file. Send me your email
if you want it and I'll send it by that.)