Bilge Discharge Hose Routing

[Blitz]

I'm having the common issue after relocating my bilge pump to the deepest part of my shallow bilge (16" or so) on my 34' Seidelmann which happens to be in the main salon behind the mast... I was attempting to get most of the water out of the bilge by relocating but what happens is that the water rushes back through the outlet hose and fills the bilge to a few inches. I also made the mistake of moving the bilge switch float to this location also so cycling occurs. A solution to this is to move my float back to where it was in front of the mast but this area is slightly shallower and although it might prevent the cycling it would not get most of the water out on auto, and if run on manual it would leave inches of water in the bilge due to the back flow.

I should clarify that my bilge hose (1-1/8") discharges high on the stern. It's a long run but that is how the manufacturer set it up and makes sense to prevent any water entering when healed. The hose does not ever get higher than the discharge so a vented loop it not an option. I use a Rule 2000 pump and a Water Witch switch.

One solution would be a check valve but I know that is a no no since it would most likely clog when you needed it the most.

Another solution would be to discharge through the side of the boat with a new through hull but was always concerned with hater coming in if healed. There are currently no through hulls on the sides of my boat above the water line except the anchor locker drain.Even my water tank vents are just high in a locker and do not discharge outside.

Any other suggestions?

Thanks for your ideas...

 

[25yearslater]

A check valve is acceptable if the cracking pressure is low enough. The pump will readily overcome any obstruction as the pressure is high enough to pump the obstruction through the hose. I am currently using one on my boat with success. My discharge is a few inches above the waterline and it effectively stops the inflow when heeled. It also prevents the cycling you refer to. Here is a link of the type I am using. With your size hose anything that could clog it indicates it's time to clean the bilge.
http://www.mcmaster.com/#standard-check-valves/=nh4jhq

 

[sailaway78]

Hi Blitz

I have tried every possible solution on my 37, which I think is exactly like yours. With the exceptions noted. ( New discharge and/or check valve.) I finally have just decided to live with it. Although I do not have the cycling problem you described. My pump and switch are located at the aft end of the bilge, and I raised the switch enough to stop the cycling. I also use a Rule 2000, and it will not suck the bilge dry anyway. So, I have about 1/2 inch of water when the switch shuts off, and maybe an additional 1/8 to 1/4 inch from hose backflow.
One thing that works pretty good is one of the diaphragm pumps, that will pump virtually dry and has no back flow, but you would have to use a manual switch to allow it to get all the water out. Not worth the trouble for me.

 

[All U Get]

A smaller ID hose would have less water coming back, but also less flow. I added a vented loop in the cockpit locker of our Catalina 30. Only the water in the hose from pump to the vent would return to the bilge. Too bad you couldn't have a shop vac on your float switch that would suck the water out and then empty overboard. A few tan ones and some duct tape is all you need.

All U Get

 

[Blitz]

Does anyone discharge through the side?

My shower sump does but is discharged below the waterline and has a vented loop.

 

[alexco38]

Yes

Why not?
Only need a vent loop

 

[Sumner]

We now have 3 bilge pumps in the Endeavour and the bilge is deep. The lowest is a smaller Rule that discharges via a vented loop below the water line to a nearby thru-hull that was for the shower, but we don't use that anymore. On "auto" the water has to get to a couple inches before it kicks on. When it kicks off it leaves about 1/2 inch of water in a depressed area that isn't too large.

It has worked well in the yard for nuisance rain water that accumulates over time. The deeper area where the pumps are is only about 1 1/2 X 2 feet so I'll live with a little water there. Since the small pump's discharge line is smaller in diameter and shorter in length to the vented loop there isn't much water that returns when the pump turns off. If we are at the boat we can run it on manual any time we care to and don't have to wait for it to get high enough to kick on. And we can also dry the area with a mop and bucket quickly.

The next pump a larger Rule 2000 is just above the smaller one and then the next Rule, also a 2000, is a little higher up. I have an alarm I'm putting in that can be switched between either the second one or to the third one. The lines for these two pumps discharge a long ways aft like what the OP has described so there will be more water flow back into the bilge when they shut off if they are ever needed but then the smaller pump should take care of that,

Sum

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[Gunni]

No reason you couldn't plumb a vented loop to reduce the volume of backflow.

 

[Blitz]

No reason you couldn't plumb a vented loop to reduce the volume of backflow.

The only reason I couldn't is that vent will need to be higher than the discharge which is currently at the top of the stern, and the hose would need to be lead from the vented loop with a gravity incline to the stern discharge. That isn't going to happen without a major refit of the cabinets etc.

If I used a vented loop for a shorter hose to discharge just below the rail the vented loop would have to be higher than the side deck. Also not very likely with the way the interior is.

A vented loop would work as I use with my existing shower sump discharge thru hull which is below the water line in that the vent could be right below the side deck. Maybe a future project to install another thru hull.

In the meantime I raised my Water Witch float switch and the run time is long enough to get enough water out of the bilge so that cycling is minimized (at least for now - might be different when sailing). This configuration as set however leaves about two inches of water in the bilge at the pump and 2-1/2" in the area of the switch. Not a lot of volume but still always water in the bilge. Rain water is an issue with my keel stepped mast so a dry bilge is not a possibility I know but I was hoping for less.

A future project might be to install the vented loop as stated above with a smaller pump that might suck it less than 2". This would be a discharge hose of something less than my current 1-1/8" and less capacity. Or even using check valves on my current shower discharge but having my current Rule 2000 pump as a non checked discharge for those times I need it.

Thanks for the ideas.

 

[alexco38]

I have a keel step mast too. Isomat injected a collar of foam just above the deck level to allow water in the mast to run out on deck.

The electrical wires runs inside a conduit and plugged at the mast top.

The boot has to be changed every 10 year or so.

No water coming from the mast.

Instead of tackling the bilge pump back flow issue, i took the approach to reduce water coming in.

Just a Different approach.

 

[Roger Long]

I'll say it again. Perhaps I should make it my signature line.

A small pump, the Sahara 750 with an integral float switch is a good choice, and small diameter bilge line. I have a very small sump and a long bilge line and no cycling problems.

Then, a second pump mounted above the first with a full size hose and float switch. This pump is only going to run if there is a flooding problem so cycling isn't an issue. It will stay dry and not be prone to getting clogged with normal bilge stuff so you can depend on it working when and if needed.

The smaller bilge line can be connected with a "Y" and reducer into the main line just before the through hull.

NO CHECK VALVE. They can sink your boat. Debris gets into them so you will still have cycling, it will just be slow cycling. The can provide enough resistance when slightly clogged with stuff carried back down the line as the leak slightly that the pump won't be able to overcome an air lock.

You can parallel wire a truck back up alarm or similar 12 volt noise maker to the large pump with an alarm shut off switch. That will alert you if the small pump isn't keeping up with the flow which it should be able to do in all non damage conditions.

 

[Blitz]

The smaller bilge line can be connected with a "Y" and reducer into the main line just before the through hull.

Don't you get backflow through the main line or vice versa if the larger pump is pumping? Or is the path of least resistance out the thru hull since it's mounted so closely? Assume you also have a slight loop in each line just before the thru hull for stern waves and to provide additional head to help prevent backflow and a path of greater resistance than out the thru hull?