Dual bilge pumps

[atwhite2]

It's probably somewhere in here that I found this, but it's a thoughtful look at bilge pumps through the eyes of the experienced surveyor and insurance claims investigator David Pascoe. Enjoy, hope you can sleep afterwards!! (I can now, but only because my 27 gets put on the hard tomorrow). http://www.yachtsurvey.com/bilge_pumps.htm

Thanks Stephen, very helpful. I am one to be over prepared, but as it turns out I might be under prepared, even with the backup.
Starting to get a bit anxious as my 30 has been on the hard for 4 weeks now and I am going through withdraw. Look like springtime brings new projects.

Thanks Stephen.

 

[seadaddler]

On my 2007 H-36 I have the normal bilge mounted in the bottom of the bilge
and than about 2' higher in the bilge is a larger high water bilge pump all installed
at the factory.
Also have a manual bilge pump at the helm and all on there own systems.
Nick

 

[JamesG161]

The major flaw in the logic is believing the lies the bilge pump maker tells you.. Bilge pumps are some of the most grossly misrepresented items we use on boats and many of us in the industry belie this is borderline criminal.

We have three major items that inhibit the performance of your pump.

Friction Head Loss
Static Head Loss
Voltage

I did the link on StephenD #20 post. They liked the Rule brand bilge. So I did a bit of research on those Pumps.
HEAD LOSS = PRESSURE LOSS or resistance to water flow. Voltage = Power use as flow increases. Low battery voltage = low Amp flow = lower pressure = lower flow.
The "pump curves" show on the vertical axis "HEIGHT IN FEET" means developed pressure with fresh water (salt water is heavier and lower height). Example: 25 Height in Feet = 10.8 PSI.
Doing a proper selection of Pumps is a bit more difficult concept, but not criminal.

As Maine Sail correctly points out, you just can't expect the 8000 gph pump to do the max. If your Static Head + Friction Head + 12VDC at the pump shows a Engineered or tested Gold "system" curve, your new fresh water pump capacity would be ≈5500 gph. The Gold curve is different for each boat and piping configuration.

If you decided a broken thru hull was your needs and you expected ≈4000 gph to keep the boat afloat while you "stopped" the leak, which pump would you pick?

1) 8000 gph
2) 1- 4000 gph and 1-2000 gph
3) Find another pump
4) Any of the above

See answer below.
Jim...
PS: The info is provided by pump manufactures to help design. The marketers blow smoke.

Answer = 4)

 

[Maine Sail]

I did the link on StephenD #20 post. They liked the Rule brand bilge. So I did a bit of research on those Pumps.
HEAD LOSS = PRESSURE LOSS or resistance to water flow. Voltage = Power use as flow increases. Low battery voltage = low Amp flow = lower pressure = lower flow.
The "pump curves" show on the vertical axis "HEIGHT IN FEET" means developed pressure with fresh water (salt water is heavier and lower height). Example: 25 Height in Feet = 10.8 PSI.
Doing a proper selection of Pumps is a bit more difficult concept, but not criminal.
View attachment 117677


As Maine Sail correctly points out, you just can't expect the 8000 gph pump to do the max. If your Static Head + Friction Head + 12VDC at the pump shows a Engineered or tested Gold "system" curve, your new fresh water pump capacity would be ≈5500 gph. The Gold curve is different for each boat and piping configuration.

If you decided a broken thru hull was your needs and you expected ≈4000 gph to keep the boat afloat while you "stopped" the leak, which pump would you pick?

1) 8000 gph
2) 1- 4000 gph and 1-2000 gph
3) Find another pump
4) Any of the above

See answer below.
Jim...
PS: The info is provided by pump manufactures to help design. The marketers blow smoke.

Answer = 4)

You can't leave out voltage and voltage drops in system wiring nor can you simply calculate for static head... Those charts only show static head not frictional head, nor do they account for system voltage or any expected voltage drop in the system wiring. The answer should be #3 Find Another Pump...

I stand by my statement that selling these pumps as 2000GPH when that is an OPEN BUCKET RATE at CHARGING VOLTAGE (13.6V rated) accounting for no head or voltage issues is, IMHO, criminal........

Problem is 99.9% of folks really don't take these things into account and they they assume they have a 2000GPH when in fact they will be lucky to get 25% of that as installed. Why does Rule not put these curves into the installation instructions??

 

[JamesG161]

You can't leave out voltage and voltage drops in system wiring nor can you simply calculate for static head...

Right on!
What if you batteries are low 11 VDC with undersized wiring? Those blue pump curves above are way off. Power at pump (watts/hp available) defines flow. Flow rate = AMPs!!!
Jim...

 

[Maine Sail]

Right on!
What if you batteries are low 11 VDC with undersized wiring? Those blue pump curves above are way off. Power at pump (watts/hp available) defines flow. Flow rate = AMPs!!!
Jim...

I guess my frustration lies in what I consider the intentional deception and intentional omitting of information they cheat customers out of.

Here is their bilge pump catalog for dealers, DIY's & such. Nowhere in there can you find any sort of specifications for voltage vs. capacity nor flow charts. Is it too much to ask what voltage the pump was rated at?

Rule Bilge Pump Catalog

And here is a Rule instruction manual, no curves, no rated voltage, no guidance on voltage drop etc...

Rule Pump Installation Instructions

They even go so far as to include this whopper of a lie...

"Step 7: Through-Hull Fittings
A. For most installations, install a 11/2" I.D. through-hull fitting to achieve
the rated flow of the pump. Locate the through-hull fitting at least
12" above the water line to prevent water from flowing back into the
hull when the pump is off."


You CAN NOT Achieve the "rated flow of the pump" as installed... Pure BS.....

If you dig deep enough you will find this:

Rule Pump Data Sheet

Sadly none of this CRITICAL information comes with the pump and still fails to include for frictional head loss or voltage losses.

But yes the pumps are rated at OPEN BUCKET which means ZERO HEAD and at 13.6V after a 10 hour break in. But sure use a 1.5" thru-hull so you can meet the "rated flow of the pump"... D'oh.... Intentionally misleading and criminal? I think so...

Here are some good questions for all bilge pump makers:

*Were are the voltage vs. GPH charts?

*Where is the suggested max allowable voltage drop for wire sizing in the installation instructions?

*Where is the frictional loss calculator for elbows, 45's, check valves, ribbed vs. smooth hose, thru-hull fittings eg: bronze thru-hull vs. Marelon etc. etc.?

*Where is the real world average "as installed" GPH pumping capability chart for a power boat or a sailboat, deep bilge vs. shallow bilge etc.?

 

[JamesG161]

*Were are the voltage vs. GPH charts?

I can help answer some of those frustrations, but not all. Nice find on the pump charts, BTW. They matched my post #23 above.

1) Flow rate is directly to Ampere rate, NOT salt or fresh water, VDC high or low, head static or friction...
A better addition to the hard to find curve, and more informative, have Power vs. GPH. Most industrial pumps have both Head versus Flow and Horsepower (watts in this case). They also include a pump efficiency curve that is normally a arching curve overlaid on the chart. See a REAL and not marketing pump curve, attached. This example is for one size pump housing and multiple impeller diameters. Pick one impeller size and you see HP on the Head vs Flow curve.
So if you can measure pumping flow versus Amps at several different flows you could plot your GOLD system curve in my #23 post ( or have a good engineer do the relatively easy calculation for you).
2) Wiring size is never a pump makers problem, but they should give you maximum Amps, (at the pump) and Volts so wiring, fuses, and even power supply must be considered.

3) Pump curve standards are done with fresh water and rated power at the pump. Always!! You must do you own conversations. For example salt water versus fresh.

4) Pump makers will never ever show friction loss data, only pump efficiencies.

5) Discharge Pressure at the pump can also tell you standard flow for YOUR system with the pump curve. In the Rule pump case, a 0-10 psi guage would work fine

But , Maine Sail, you are on Target with the misleading sales documents!

This may be boring and for tech types,

BUT YOU have to consider the factors!

The boomerang shaped curves are efficiency %. This a real pump curve.
What Rule Pumps did was bare minimum and surely frustrating to someone asked to size the right pump.
Jim...

PS: I hope this was not too nauseating.