One for the Good Math Students (livewell pump)

[loebs93]

If I have a 500 gallon/hour pump and a 12.5 gallon livewell (really its 20 gallons, but given the position of the overflow hole it will only hold 12.5 gallons, which is plenty for our boat) for the livewell I am building, how long (minutes) will it take to fill up?

My girlfriend and I worked on this problem last night for quite some time. Eventually we got an answer-we think-but we couldn't figure out the algebra part, so I figured I would run this by all you math whiz FMers to see what you get. If you get an answer try to show me your work.

I kept telling myself that this was no big deal and I shouldn’t be wasting my time on it, but I couldn’t just give up. I know it’s not that hard to figure out the answer, but the algebra was just killing me last night.

See how you do.

Thanks

[gundy89]

I'm a little rusty but here goes:

(500 gallons/hour)/ (60 minutes/hour) = 8.3333 gallons/minute

(12.5 gallons)/(8.3333 gallons/minute)= 1.5 minutes

[fish-n-geek]

Eighteen minutes :-)

30 seconds for turning on the switch and getting no water, then flicking the switch a few times to see if that works.

5 minutes to crawl under the console, find the fuse panel, figure out how to open it, get the fuse out, find out its still good, put it back in, get the cover on, swear repeatedly when you bang your forehead on the console crawling out from under it.

Another 5 minutes staring at the problem until you figure out the aux wires aren't connected to the battery.

One minute to hook up the battery and flick the switch a few times. To find out you forgot to charge *that* battery...

Five more minutes to move the cables over to the other battery and turn on the pump.

Then 1.5 minutes at 500gph to run 12.5 gallons.

[Deitz Dittrich]

I think gundys math is correct.. however, many pumps that say 500 gallons per hour are measured with the nossle off I believe.. So when you put the nossle on to make it spray in the livewell it may take a tad longer... However, one who goes threw this much trouble to figure out how long it will take to fill a livewell has WAY to much time on thier hands...

You should concentrate on will the overflow empty at 500 gals per hour, does the bilge pump empty fast enough to make up for the overflow that isn't above the 500 gals per hour.. and DID I PUT THE BOAT PLUG IN?

[lawdog]

I agree 1.5 minutes, but I also think Dietz hit it on the head! Can you drain it in the overflow that fast? I think this is too big of a pump!

[musky hunter]

The big assumption is that the pump rating is what it pumps. The small pumps are rated at 500 gph, but that't the maximum output of the pump no hoses, no pumping head, no resistance through the fittings. As soon as you hook up a pipe to the outlet of the livewell pump the actual capacity varies, and it is SUBSTANTIALLY LESS than the manufacturer promised. Therefore, all you mathematicians did the math right but got the wrong answer. The real answer is, we can't actually tell from the information provided, go put the boat in the water and get out the stopwatch to find out!

[Deitz Dittrich]

we could have a pool.. and guess.. ... My guess closer to 2min 5 sec.

[gspman]

In the immortal words of Roman Maroney - "THAT'S A FARGIN' TRICK QUESTION!!!"

[fish-n-geek]

Good catch Deitz. I just bought a 750 gph when my old pump fried. (it was $3 cheaper than the 500 gph ? ). It actually has two ratings in the not-huge print. 750gph with 0 head and more like 580 or something with a 3' head.

Either way, it fills my live well faster than the 1/2" pipe can drain it, so if I forget its running, it will overflow!

-r-

[loebs93]

Haha...It was supposed to be something easy to figure out .

I had 1.5 minutes as well. I understand it will probably take longer than that to fill, but it was still fun to try and figure out.

I don't care how fast it pumps the water, I'm just happy to finally have a livewell .

[Guest]

The longer the livewell hose is,the pumping rate will drop as it takes alot to pump a further distance,my bet is 5 mn.if you have more than 6 feet of hose.

[Valv]

Ok, I have a better solution. Lets' post how long it takes on each of you to fill up your livewell.

Since all the boats have 500gph or 750gph with few 900gph, it won't take much to find out.

Let's start timing....

[Deitz Dittrich]

True valv.. but different size livewells! I may rig my livewell up with twin 500 gph, and turbo charge them.. then put in a 10 gal plug to fill the bottom of the livewell.. JUST SO THAT I CAN WIN!!!.. ok maybe not.. back the real world!

[Valv]

Deitz, lets cheat. Hook up 2 batteries, 24 volts....

I will replace yours for free when it blows.... but we'll be first

Just be sure you'll be there when it works, don't go answer the phone and find your boat sinking for overflowing of livewell, or worse boat on fire since pump got too hot with 24v....

[Guest]

Dietz and Valv--If you guys would just install your overflow below the water line your livewell would not even need a pump and it would fill real fast,with a pump you could set records and sink or now figure out how long it would take your bilge pump to empty out.

[Surface Tension]

Ahh, but what if I placed 6 eyes in that live well while it was filing. After all your not going to fill your well if theres nothing to put in it.

[Deitz Dittrich]

LMAO @ all of you!..

[RonZych]

I would never fill my livewell with lake water! First off it will be filled with ice to keep the things cold that make me feel better when I'm not catching fish. When I do catch fish I fill the 2nd livewell with carbonated mineral water.(They seem to like the french stuff the best) It really keeps them fresh. When I hit the recirculation switch its a beautiful fountain of bubbles and smiling fish.