Plumbing pump suggestions?

[Cyrus Safdari]

I want to arrange the plumbing aboard for all limber holes to be connected by hose together to a pump to go overboard rather than draining into a sump for a submersible bilge pump to deal with, and I don't want a sump box with submersible bilge pump arrangement. This needs an inline pump with an auto flow switch
I think Rule makes the pump but no switch

Typically on boats the cabinets, compartments and lockers are supposed to have limber holes that allow water to drain into bilge sump where a bilge pump resides. I am putting barbs on limber holes to connect then together to a single drain hose
Greywater like shower and head/galley sinks drain into sump boxes where another bilge pump resides
Instead of sump boxes it is possible to use an inline pump that has a built-in flow sensing switch, which senses when water is accumulating in the (combined) input-side hose and so turns on the pump. This way,, multiple compartment drains can be connect by hose together, fed directly to the pump to drain overboard..
I only know of the Whale Gulper IC that serves this purpose but I believe it is a diaphragm pump not a centrifugal pump. Diaphragm pumps of course has the benefit of being able to deal with small crud, can run dry and are self priming, which is as you'd want for a Grey water pump. They also don't have the capacity of centrifugal type bilge pumps, which are not self priming and can't really deal was well with crud and can't really run dry.

However for my purposes I want a centrifugal pump not a diaphragm pump. In my application there is no concern about self priming since the inline water flow sensor will be positioned low in the line, feeding the pump below it; there is no concern over crud with filters & I want the higher capacity of a centrifugal pump
Or if not, suggestions for a marine-worthy 12 flow switch I can connect to an inline pump?
Thanks

[SVTatia]

I think that a in-line sensor for a hose or similar will trigger too many cycles and some may not be enough to "lift" the water outboard.
If you want to avoid water sloshing in the bilge, another option would be to have the hose end in a sealed container large enough to accommodate a pump with an internal switch.
But keep in mind that these solutions will prevent the pump from removing water efficiently in case of a major flood.

[SailingHarmonie]

So...

You get 50 ml of water that comes down the tube and touches your sensor...what do you want to happen? Run for a tenth of a second and then stop?

I really do appreciate the attempt to get a dry bilge, but this just won't work as you imagine. Somewhere you NEED a place to accumulate water for the pump to work with, if you are going to have a pump with any real capacity at all.

[Bowdrie]

Typically, centrifugal pumps need a constantly flooded inlet to work.
An air bubble can easily cause the pump to lose prime.
They can move a lot of water fast but any air stops them.
Trying to collect water from hoses run to a multitude of places that are at various levels seems like a losing proposition.
I'm not sure that this wheel can be re-invented.

[Cyrus Safdari]

LOL reading the replies I guess some people are skeptical about what is actually a pretty normal plumbing arrangement that they're just unfamiliar with: Nobody is reinventing any wheels folks, the multiple drain hoses leading to a remote pump with an inline sensor arrangement already exists, there is a commercial product specially made for this: the Whale Gulper IC with a manifold fitting (it uses an inductance sensor too so it senses the water without touching it)

"to manage waste from multiple drains with intelligent control built in. Compact automatic system handles waste drainage from two outlets...When the manifold senses water it sends an electrical signal to Gulper IC which evacuates the system. As the water level decreases the electrical signal transmitted by the manifold will cease. Gulper IC will continue to operate for a further 15 seconds before turning off." https://www.whalepumps.com/marine/si...33_v1_0410.pdf

Typically these are used to automatically drain both the shower and sink in the head but there's no law of nature that says you can't use them to drain other places where water can potentially accumulate like wet lockers. I am making multiple water-tight compartments in the boat (lockers under settes and under V berth etc) and each need drainage in case water enters. I of course don't expect the pump to keep up with a hull breach, that's not the point, just as a drain. (and there's no bubble problem since they all drain down, the pump is always primed as long as the input hose has water in it)

BUt this is a diaphram pump of course, so I'm trying to figure out if a similar product exists with a centrifugal pump with higher capacity. Rule does make a 3800 gph two-port centrifugal pump (which is basically a submersible bilge pump with a cowl port attachment) but it lacks the sensor function described for the Whale pump.

I don't want to make this from scratch but it would not be hard
Flow sensor switches can be set to various sensitivity settings, they can be programmed too so for example they turn on after a certain volume of water is attained in the hose and/or set amount of time has passed, and to stay on for a set amount of time etc. This is basic electronics stuff. There are cheap programmable off the shelf 12v timers too. BUT I was kinda hoping there would already be a comparable off-the-shelf product as the Whale with a centrifuge pump instead of a diaphram pump

[Bowdrie]

You are not going to get any centrifugal pump to work with a few ounces here-and-there of water going to some inlet manifold.
A centrifugal pump MUST have a flooded inlet.
That's why boats have sumps, so a centrifugal pump in that sump can work.
The pump would have to also be mounted below all your plumbing.
They also don't like check valves in the outlet.
So, assuming enough water volume that the pump turns on. Then when it turns off all the water in the discharge hose just runs back thru the pump and the hoses connected to its inlet, just like a regular bilge pump.
Edit, your option might be an impellor pump, like this Jabsco.
https://marinepumpdirect.com/jabsco-pumps/

[Cyrus Safdari]

Originally Posted by Bowdrie

You are not going to get any centrifugal pump to work with a few ounces here-and-there of water going to some inlet manifold.
A centrifugal pump MUST have a flooded inlet.

Yes, the water in the inlet hose is flooded if it is draining a compartment. The switch on the Whale product is set so it doesn't turn on for dribbles either; the pump should turn on only when there is more than just a dribble, regardless of the type of pump. This is programmed into the flow switch sensor

That's why boats have sumps, so a centrifugal pump in that sump can work.

While it is generally true that centrifugal bilge pumps are of the submersible variety that sit in the sump water they are draining, this is not a requirement and the Rule pump I've repeatedly mentioned accomplishes this by attaching another port to where the grill would normally go
Im getting tired of mentiong that so here's the picture of the pump, this would work for me if it had the "Intelligent Control" (IC) switch that the Whale product has

The pump would have to also be mounted below all your plumbing.,,,runs back

Yup that's the plan & mounting pumps low is generally applicable advice for all pumps even self priming ones
As for water running back, the pump switch on the Whale product stays on for an additional 15 secs, just as most more modern bilge pumps switches. This is not hard to accomplish if I had to make it from scratch so I was hoping there is a product that has 1- the same switch function as the Whale, and 2- with a centrifuge pump instead of a diaphram pump

[rslifkin]

Either type of pump would work if you end up with significant water in a compartment. But either a sump, or the diaphragm pump that will trigger with even a tiny bit of water is the only one that'll take care of small amounts of water effectively (like if a couple ounces gets spilled in a compartment).



Is there any particular reason you wouldn't want a diaphragm pump for this job?

[Cyrus Safdari]

Originally Posted by rslifkin

Is there any particular reason you wouldn't want a diaphragm pump for this job?

Because with the centrifuge pump's greater capacity I can have longer hose runs and more conveniently-placed outlet thruhulls
This arrangement is not meant to deal with just a dribble of water at a time, it kicks on when the input hose fills and needs emptying just as sump pump
The Whale product works for this purpose; it only uses a diaphram pump because it is meant for gray water with crud in it but there's no reason why a centrifuge pump with a similar switch can't be used for the same bilge draining purpose as long as you have a decent filter and place it low enough to ensure priming

So I am guessing this doesn't exist so I can either go with the Whale Gulper IC with manifold and deal with the hose length limitations or tryi to put a similar functioning thing together

[Bowdrie]

Originally Posted by rslifkin

Either type of pump would work if you end up with significant water in a compartment. But either a sump, or the diaphragm pump that will trigger with even a tiny bit of water is the only one that'll take care of small amounts of water effectively (like if a couple ounces gets spilled in a compartment).
Is there any particular reason you wouldn't want a diaphragm pump for this job?

Yeah, I guess I've not been too clear.
I'm failing to understand why a bunch of storage areas/lockers/cabinets, etc., all have to be configured as watertight compartments and need drain hoses feeding a pump.
Condensation? or are we trying to replicate a submarine?
The entire process seems an exercise with little to no redeeming value, hoses run hither-and yon to collect small amounts that just as well could drain into a normal sump.
Regardless, centrifugal pumps are a poor choice for having a dry compartment or bilge.
It's not what they were designed for, nor are their provisions for backflow.

[rslifkin]

Originally Posted by Cyrus Safdari

Because with the centrifuge pump's greater capacity I can have longer hose runs and more conveniently-placed outlet thruhulls

The Whale product works for this purpose; it only uses a diaphram pump because it is meant for gray water with crud in it but there's no reason why a centrifuge pump with a similar switch can't be used for the same bilge draining purpose as long as you have a decent filter and place it low enough to ensure priming

Long hose runs, etc. shouldn't be a problem with a diaphragm pump. It's a positive displacement pump, so flow rate will suffer far less from long hoses (especially on the discharge side) than a centrifugal pump would. And diaphragm pumps don't allow backflow, so water remaining in the output hose won't return to anywhere before the pump when the pump stops.

[Bowdrie]

Originally Posted by Cyrus Safdari

Because with the centrifuge pump's greater capacity I can have longer hose runs and more conveniently-placed outlet thruhulls

That entire statement is self-defeating.
Do you anticipate massive flooding in a locker/cabinet/storage area?
Long discharge runs are a bane of any centrifugal pump.
You're approaching this whole thing from the wrong angle.
Setting-up a bunch of drains with a multitude of "computer controls" to monitor and control some water, and then expect a pump which will lose its ability to pump with only a slight air leak into the system is unrealistic at best.
And when your centrifugal pump shuts off the entire contents of your "longer hose runs" just drains back thru the pump into the hoses from whence it came.

[Cyrus Safdari]

Originally Posted by Bowdrie

I'm failing to understand why a bunch of storage areas/lockers/cabinets, etc., all have to be configured as watertight compartments and need drain hoses feeding a pump....

It's not what they were designed for, nor are their provisions for backflow.

Backflow is not an issue and has not been for a long time now, as I mentioned most bilge pump switches as well as the Whale Gulper's "Intelligent Control" are programmed to continue pumping for a few seconds after they've emptied their compartments to deal specifically the issue of backfkow - and this not hard at all to program on off-the-shelf switches if I had to make this switch from scratch

As to WHY I want to do this, that's a separate thread but I am rebuilding my boat to ISAF - ORC Cat 0 standards with multiple transverse bulkheads and watertight compartments. I've converted half the bilge into two integral water tanks and I filled-in the rest with expanding foam and glassed over it so there are no dark inaccessible areas (in addition to planning to glass-in foam below waterline effectively making her double-hulled below waterline) and adding longitudinals and anyway as a general matter IMHO any boat should have as many water tight compartment as it can & all the locker lids should be gasketed with latching mechanisms etc. etc.

[Uncle Bob]

That entire statement is self-defeating.
Do you anticipate massive flooding in a locker/cabinet/storage area?
Long discharge runs are a bane of any centrifugal pump.
You're approaching this whole thing from the wrong angle.
Setting-up a bunch of drains with a multitude of "computer controls" to monitor and control some water, and then expect a pump which will lose its ability to pump with only a slight air leak into the system is unrealistic at best.
And when your centrifugal pump shuts off the entire contents of your "longer hose runs" just drains back thru the pump into the hoses from whence it came.
_____________

^^^^^
This There already is a system available, I believe it is called dry bilge.

[rslifkin]

Originally Posted by Cyrus Safdari

Backflow is not an issue and has not been for a long time now, as I mentioned most bilge pump switches as well as the Whale Gulper's "Intelligent Control" are programmed to continue pumping for a few seconds after they've emptied their compartments to deal specifically the issue of backfkow - and this not hard at all to program on off-the-shelf switches if I had to make this switch from scratch

You can run a centrifugal pump for an hour after it's sucked up all the water, you'll still get backflow. Once there's no more water coming in, it can't generate any meaningful output pressure, so it can't push more than a little bit of the water out of the output hose. Once the pump stops and the water is free to flow back through the pump, it will.