Bilge pump upgrade. Bigger hose and wiring needed?

[MC3387]

Hey there, I want to replace the bilge pump on my 24’ cuddy, and I want to go with the biggest pump possible.
I hear that you can’t just throw in a bigger pump without possibly changing to a bigger discharge hose and electrical wiring.
So how do I go about shopping around for “the biggest pump I can”? Do I just measure the diameter of my discharge hose and then look at pumps and see what size hose they recommend using? Seems like that would be a slow process.
Is there a standard for hose diameter and pump gph that I could look at before shopping for pumps to expedite the pump selection process?
And what about the wiring? Do pumps manufacturers tell you what gauge wire you should use for their pumps?

 

[Scott Danforth]

what size discharge do you have now? 3/4"? 1-1/8"? 1-1/2"?

stock pumps are usually 500 gph. some are 800 gph

1-1/8" thru-hulls will flow up to about 1200-1500 gph. to go bigger, go with a bigger thru-hull.

however keep in mind, a bilge pump wont help with a hull breach.

 

[mr 88]

Just get a 1500 gph and hook up to your existing hose after measuring, might need to go to a smaller pump. If you take on more water than that your going to need a Fire Companys diesel powered pump to keep up with it. Or buy two 1500/800 pumps and hook them.up directly to the battery ,they do not draw big amperage ( rule 1500 7 amps / SeaFlo 1500 8 amps ,both 1"- 1/8 outlet ) so I would not overthink the gauge size . Out of curiosity , why the need or worry about getting the biggest vs what the mfg installed.

 

[MC3387]

Out of curiosity , why the need or worry about getting the biggest vs what the mfg installed.

I have to replace my bilge pump anyway so I figured I’d go with the biggest one I can find that matches up with my discharge hose and through hull fitting. When it comes to bilge pumps im under the impression that bigger is always better.

 

[mr 88]

Nothing wrong with getting the biggest one that matches up to your hose ! Your 1st post did not mention it was broke , just that you wanted to replace it. Lead me to think you were set on upgrading because of maybe taking on too much water for whatever reason. And to me at that point , your going down no matter the pump size . Worried about the wiring , just compare the amperage on whatever you have now vs the biggest one that fits your setup , should be within a amp or two and it would help if we knew what gph pump is in it now to answer some of your other questions.

 

[Bt Doctur]

most builders give you a pump to keep up with your urine discharge. Get a 1500 at a minumun, 1800 is better. Both use 1 1/8 discharge hose, Can have both wired with their individual float switches or both on a "manual " switch Leave whats there now and just add another

 

[MC3387]

Nothing wrong with getting the biggest one that matches up to your hose ! Your 1st post did not mention it was broke , just that you wanted to replace it. Lead me to think you were set on upgrading because of maybe taking on too much water for whatever reason. And to me at that point , your going down no matter the pump size . Worried about the wiring , just compare the amperage on whatever you have now vs the biggest one that fits your setup , should be within a amp or two and it would help if we knew what gph pump is in it now to answer some of your other questions.

I actually left the bilge pump on by accident for about 3 days. Ran dry the entire time. I’m also wanting to install a float switch. So I figure while I have everything pulled open to access bilge(it’s a PIA to access) I might as well drop $60 and just install a new pump in case mine that was left on is damaged.
Other than that my bilge area stays practically bone dry.

 

[MC3387]

most builders give you a pump to keep up with your urine discharge. Get a 1500 at a minumun, 1800 is better. Both use 1 1/8 discharge hose, Can have both wired with their individual float switches or both on a "manual " switch Leave whats there now and just add another

I’d like to leave what I have now and add another but I really don’t want to drill through my boat to create a new through hull for the new pump discharge hose. So I’ll probably replace what I have now that’s already plumbed up and then possibly get a back up bilge I can leave under the seat that alligator clips to your battery for use in emergency.

 

[hugh g]

Get the biggest gph pump you can fit in your bilge with your existing wiring etc. The pumps that boat builders use are for the most part garbage thrown in to meet minimum CG regulations. A 500 gph pump won't pump anywhere near 500 gph (like 30% of that) once you factor in head height, length of discharge hose etc. A bilge pump may not save your boat but it can buy you time. The smaller the boat the faster it will fill up with water.