how big of bilge pump do i need?

[tlc19641982]

i have a 93 cajun 200 hp, about 20ft, the bilge pump in it finally quit, it was in the boat when i bought it. i want to upgrade, it had a manual 650 pump in it. i want to put a automatic one in, i have seen a couple of types. one with a separate float switch and one with a built in float switch in the pump. which type is better and what size do i need, and which brand is better?
thanks
dee

 

[phwrd]

Re: how big of bilge pump do i need?

Welcome to Iboats.

A 20 foot, 200 hp boat is going to stand up pretty good. Might suck in a lot of water. How deep is your bilge ? Any leakage when floating ? Can you see into it while running ?

I would get 2 pumps for your boat. First one would be the Largest auto I could afford (750 - 1000) that also fits the existing tube/thru hull fitting.

Use smooth bore hose, corrugated tubing is cheap and easy but will greatly decrease the efficiency of the pump. Double clamp everything with stainless if you can. 2 Radiator clamps are better than one stainless.

2nd, I would get a larger one with a float switch, If you have room, mount the pump on the bottom, float switch a little bit higher in the bilge. With a warning light or buzzer. I have always had good luck with Rule brand.

But then again, I am a bit paranoid about my boat disappearing out from underneath me.

 

[redone4x4]

Re: how big of bilge pump do i need?

i saw an 800 gph Rule automatic pump for around 60 bucks this weekend...i would go with something along the lines of that.....i also agree that a 2nd pump wouldnt be a bad idea, but i only have one and just check its operation on a regular basis.

 

[BaileysBoat]

Re: how big of bilge pump do i need?

2nd the 2 pumps idea.

http://www.yachtsurvey.com/bilge_pumps.htm

 

[Blue Crabber]

Re: how big of bilge pump do i need?

I throw my 2 cents in here and say go with the 2 pumps as well like phwrd suggested. That is the way I had my last boat wired up. I had a 750 gph with an internal float. Then i used a 2000 gph manual pump. I figured if I ever needed to turn on the second pump, there was a real problem and I wanted a big pump to handle it.

Just got a newer boat and working on doing that to this one. Safety first. You might never need it but if you do, you will be glad you have it.

I am guessing you are aware that bilge pumps ratings are never actually achieved. The ratings are at around 14 volts normally and with no discharge hose or lift. Adding a hose and pumping the water up 2 feet drops the rating significantly. Just an FYI. That is the reason I went so big with the backup pump.

 

[tlc19641982]

Re: how big of bilge pump do i need?

thanks everyone for your replies. i will go with 2 pumps, this is my first nice boat and i really don't want to see it sink. again thanks to everyone and have a great day.

dee

 

[The Famous Grouse]

Re: how big of bilge pump do i need?

One critical aspect that has not been mentioned is to make sure the correct size wire is used for the pump.

All electrical wire has resistance. The smaller the wire gage and the longer the run, the higher the resistance and the lower the available voltage to operate the pump.

I've seen a boat that came from the factory with tiny 14 gage wire to the pump. With 25 feet of wire run, that means that only about 10 volts were available at the pump, so when you include the lift that the pump had to overcome, a 1000 GPH pump could barely operate at 50% of its advertised capacity!

Bottom line is make sure the wire is up to the task and make sure all connections are done properly with all connections made above the bilge waterline. You should aim for a voltage drop of <5% at the pump, and IMO a drop of >15% is not acceptable and a higer wire gage must be substituted.

I second the idea of adding a backup pump, but a second pump is no substitute for a proper installation that has the pump running at near maximum capacity given the lift requirement and the available voltage.

Grouse

 

[Mark42]

Re: how big of bilge pump do i need?

I agree with the two pump setup. A 750 gph set low in the bilge for regular duty, and a second 750 or larger set 6" or so higher so if the first pump is being overwhelmed, the second pump will kick in.

Remember, bilge pumps are not intended to keep you boat from sinking when it gets a hole punched in the hull. Even a 2" diameter hole low on a boat will overwhelm a 1000gph pump in minutes. The real function is to pump out rain, water splashed in, etc. It needs to be large enough to handle heavy rain for long durations. If you got a 4" log stuck through the hull, your going down unless its full of flotation foam.

And dual pumps should be fused, wired and plumbed completely independently of each other. No sharing nothing.

 

[bob johnson]

Re: how big of bilge pump do i need?

2 1000 to 1200 GPH bilge pumps is what i would recomend.

of course I am a duck hunter and go out in rough weather...swells and rough seas are the norm...take on a few rogue waves and you might not be in serious trouble if you can get some of that water out in a hurry before you get some more blind side you.....

I would wire them manually myself...i dont want an auto getting stick and running my battery dead...

but I never moor my boat over night..I trailer it every place i go.


for Famous Grouse:

how about a 10 foot run of wire to 1000GPH pumps?

is 16 too small?


I looked up the rule website:
http://www.rule-industries.com/products/pumps/bilge_pumps/rule_1100/iid_244/index.htm

says the 1100 only draws 3.3 amps? shouldnt need special wire for that should ya?

thanks

bob

 

[This_lil_fishy]

Re: how big of bilge pump do i need?

2 1000 to 1200 GPH bilge pumps is what i would recomend.

of course I am a duck hunter and go out in rough weather...swells and rough seas are the norm...take on a few rogue waves and you might not be in serious trouble if you can get some of that water out in a hurry before you get some more blind side you.....

I would wire them manually myself...i dont want an auto getting stick and running my battery dead...

but I never moor my boat over night..I trailer it every place i go.


for Famous Grouse:

how about a 10 foot run of wire to 1000GPH pumps?

is 16 too small?


I looked up the rule website:
http://www.rule-industries.com/products/pumps/bilge_pumps/rule_1100/iid_244/index.htm

says the 1100 only draws 3.3 amps? shouldnt need special wire for that should ya?

thanks

bob

I'd say you're pretty good. I've used 18 for lighting, which draws a fair bit more current. Heck, GM uses 20guage for headlights!

Ian

 

[Mark42]

Re: how big of bilge pump do i need?

At 10 feet, the wire gauge should be 14 (AWG) to get a minimimal voltage drop. The smaller the wire, the higher the voltage drop will be, and the pump will run slower.

Also note that marine wire is rated in the American Wire Gauge (AWG), which is 12% larger than the Society of Automotive Engineering (SAE) gauge. If you are buying wire at the auto supply, or Radio Shack, remember to go one size larger to keep within the specs for your pump. More important, although SAE wire meets minimum marine requirements, it does not meet requirements for bilge pump use because of the moisture and fuel/oil restance requirments of bilge pump wire.

BTW, before you buy a Rule pump, you should check out the Attwood line. Their S750 and S1100 both pump more than the Rule 750 and 1100 at 3.3 feet of head at the same voltage, and do it using less amps. The review I read rated the Attwood pumps performance the best, but knocked them down for not having tinned wire, they just had marine grade wire. That was a few years ago. Now all Attwood pumps (except for maybe the smallest manual pumps) come with tinned marine wire standard.

The amp rating is important for boats that are moored. Less amps used means the pump will run longer than a pump using more amps.

If you don't know where to buy marine wire, a number of members (myself included) have had great experiences buying from Greg at gregsmarinewiresupply.com Look at the 3 wire bilge pump wire. It makes switching a pump easy, and has an extra heavy jacket to protect from chafing, water and gas.

If you are adding a pump for the first time, you might find this project interesting: http://shareaproject.com/pages/projectTut,p,512,00.html

Spend your money wisely.

 

[Home Cookin']

Re: how big of bilge pump do i need?

I have a 21' Sea Hunt CC. There are two scuppers flush with the floor, with flappers, to drain the cockpit. There are no other openings to the bilge except the deck plates around the console and over the gas tank. Even the rod holders drain into the cockpit. Fish and anchor lockers drain overboard.

Now, I know that some water will seep through the edges of the plates to the bilge, but otherwise any major water, from a wave or a downpour, will go out the scuppers. So realistically, am I at risk of overwhelming the bilge pump, other than if there is a through-hull failure? Maybe I should rig a cockpit pump (I have a bucket) instead of 2 bilge pumps?

Actually, I'm being a little academic here b/c I won't tempt fate. I plan to rig a second pump for back-up and I bought a hand pump as a first piece of equipment. Now that I'm curious, I might plug the scuppers and run a hose in the boat, and observe how much seeps into the bilge from the deck. I already sealed the interior of the console, a notorious leaker for Sea Hunts.
I keep the boat moored so the pump is important.

 

[IVAZ]

Re: how big of bilge pump do i need?

I think the smaller the boat the bigger the bilge pump should be (small boat will fill up with water quicker).
My old 18 footer has two 1500gph pumps installed. It might be overkill but I usually buy good stuff when it comes to safety gear.
They are there but never get used. Unless we take on some waves or we come in from swimming it stays dry. So far they have not kicked on for any reason.