Bilge pumps - BS ratings?

[ZmOz]

I am replacing the bilge pump in my boat since it's been sitting out in the weather all winter and I don't trust it anymore. The pump is a Rule 360GPH, and I've measured the amps it uses at around 2.5. I was looking at Bilge pumps today at a local boating store, and they have the same Rule 360gph and an Atwood 500GPH for about the same price. The Atwood pump claims to only use 1.5 amps.<br /><br />How can this pump use so much less power than the Rule and be 140 more GPH? Are these ratings just BS, like the CFM on most air compressors? <br /><br />Basically, my question is which do you think pumps more?

 

[JRJ]

Re: Bilge pumps - BS ratings?

I would buy the the most GPH pump that will fit in the space, and hope I never need it.

 

[ZmOz]

Re: Bilge pumps - BS ratings?

Originally posted by JRJ:<br /> I would buy the the most GPH pump that will fit in the space, and hope I never need it.

That's what I intend to do, but it seems to me a 2.5 amp pump is going to move more water than a 1.5 amp pump...no?

 

[Ralph 123]

Re: Bilge pumps - BS ratings?

Read this:<br /><br /> http://www.rule-industries.com/rule/faq.asp <br /><br />

Q: It seems that most manufacturers make exaggerated claims about GPH (gallons per hour) performance. How should pumps be compared? <br /> <br />A: Most marketplace ratings are made at optimum voltage (13.6 vdc) and zero discharge head. To really compare performance, review each manufacturer's real world performance by checking the flow at 1meter (3.35 feet) and 2 meter (6.7 feet) discharge head. <br />

 

[walleyehed]

Re: Bilge pumps - BS ratings?

Maybe the impeller, just like a prop, is designed for better efficiency in one than another..........????????

 

[18rabbit]

Re: Bilge pumps - BS ratings?

The ABYC wants bilge pump discharge to be rated with 3 different numbers; no head and no hose, 1-meter of head w/10-ft hose, and 2-meter of head w/20-ft hose.<br /><br />Few (none?) bilge pumps will produce the claimed gph with zero head. Some are better than others. For those little bitty pumps like you are looking at, Whale comes the closest to hitting their umber, 95-99% of the discharge they claim, both at 13.6vdc and 12.2vdc. that’s for pumps in the 400 to 625gph range. Rule hit 75-86% of their claim, Attwood 67-73% of their claim. This is the result of when the pumps were tested to the ABYC standard of 1-meter/10-ft of hose.<br /><br />Whale pumps have some of the shortest wire leads, the wire is rated to 300v and 80-deg C, and all other pumps have wiring rates to 600v and 105-deg C. I’m not sure that difference in wiring is important. Whale and Lovett have the shortest warranty term of all pump manfs, 1-year. Rule and Attwood both have 3-year warranties.<br /><br />How to buy a bilge pump:<br /><br />(1) Pick up the package.<br />(2) Flip it over, does it say ‘made in China’? If so…<br />(3) Put it back.<br /><br />The greatest gph discharge will come from a pump hose that has smooth walls inside.

 

[Silvertip]

Re: Bilge pumps - BS ratings?

If you have to worry about 1 or 2 amps difference in current draw, there are other problems to consider. Buy the biggest pump you think you need, fuse it accordingly, and like JRJ says "hope you never need it". I just bought a 750 GPH pump and its rated at 2.5 amps. Do I believe the rating -- nope! But if the rating is even half as much as claimed, it will do the intended job (suck a 25 gallon live well dry in a heartbeat).

 

[Scaaty]

Re: Bilge pumps - BS ratings?

It also depends on the boat. And anything under a 1000gph is cutting corners. Big boats with lots of bilge room will take a LONG time to sink. Smaller boats have less room, engine closer to bilge, etc, will have less time to come up with a plan in a emergency. And ALL pumps should be on auto. Now if you just want to pump out rain water, a 500gph fine, even smaller, but do a cost analysis here. Heavy rain, and whats a starter motor cost? Seen it happen in the slip across from me.....,.

 

[ZmOz]

Re: Bilge pumps - BS ratings?

Originally posted by Upinsmoke:<br /> If you have to worry about 1 or 2 amps difference in current draw, there are other problems to consider.

I don't care what the amp draw is. It could draw 10 amps for all I care. The topic of this thread is, is amp draw a better comparison than GPH? I think it is...<br /><br />

Originally posted by Robby6950:<br />And anything under a 1000gph is cutting corners.

As far as I can tell, this boat has not had a single bilge pump installed in it's 30 years of life before I got it. It's done fine with 0 GPH. The pump is only intended to remove the water from climbing in and out of the boat, as well as any large waves that may come in. If something ever happens where I need more than 360gph to stay afloat, I'll just let the damn thing sink...<br /><br /><br />Thanks for the thoughts guys, I think I'll just go with the Rule. The one I'm replacing has been run 24/7 for months in my pool, and left out in the weather all winter, and still works fine...I think that proves it's quality. Wouldn't have the slightest idea where to buy a Whale pump.

 

[Sea Six]

Re: Bilge pumps - BS ratings?

Get a pump that uses the size hose you have. The bigger pumps need bigger hose, and yours won't fit without an adapter.

 

[trog100]

Re: Bilge pumps - BS ratings?

just for interest.. the new auto pump i just bought (cant remember the make) is rated at 750 (US) gph at 13.7 volts and draws 4 amps.. the rating at 12 volts is down to 550gph and and the amp draw down to 2.5 amps.. quite a difference between the two.. i just tested it by pouring some buckets of water into the bilge.. at 12 volts it shifted the water out far quicker than i could pour it in.. he he<br /><br />i wired it to straight to the battery terminals to make sure it always on.. more a peace of mind thing than anything else cos my boats stays perminently in the water..<br /><br />trog100