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Old 12-31-2002, 08:10 PM   #1
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Default Installing 2nd bilge pump

I am in the process of installing a 2nd builge pump on my boat. Do I cut a new hole and add a new fitting for the water to exit or do I try to tap into the existing line. The existing line is kinda a flexable type hose, not sure it will stand up to too much pressure. I am sure it is just fine for the 1100GPH pump that came with the boat but I am looking at a 3700 or 4000GPH 2nd pump. I have room and access to cut another hole right next to the existing bilge exit hole.
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Old 12-31-2002, 08:25 PM   #2
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Default Installing 2nd bilge pump

I think I would try to pipe up a second pump discharge. If the piping on the first pump is as flimsy as you say, shouldn't you be prepared for it to bust. Only one thing worse then 1 bilge pump discharging back to the bilge, that's 2 bilge pumps recycling to the bilge.
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Old 12-31-2002, 08:54 PM   #3
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Default Installing 2nd bilge pump

Look at the size of the discharge hose, on most of the very large pumps its greater than the 1 1/8" that your smaller pump is. That of course means that you'll be in the new fitting market if you want a big pump (often 1 1/2"). Also, you can, and should, buy smooth bore hose that is substantial. In fact one of the real problems with it is that is not very flexible so it can be a bear making the connections. Doable, just a pain. The real up side isn't so much that its stronger , (there is basically no back pressure on a bilge pump line other than the head and that only comes to about 1 pound per square inch for each 2 feet of rise) but that it allows a much greater flow of water. That thin wall corrigated stuff is hell to pump water through.


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Old 01-01-2003, 07:53 PM   #4
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Default Installing 2nd bilge pump

Definality add the new fitting for discharge. We don't need any bottlenecks if you need both pumps at one time. Now to the discharge hose. Is it that plastic segemented crap? If it is GET RID OF IT! It's junk! I can't belive they sell that stuff for bildge hose. The segments slow and restrict water flow and it's just cheap A$$ stuff. Would you risk your life on it? Use the Series 162 polyester reinforced clear PVC tubing. Your life may depend on it!
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Old 01-01-2003, 09:38 PM   #5
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Default Installing 2nd bilge pump

I found the 162 polyester reinforced clear PVC tubing you were talking about in my West Marine Catalog. I will rig the new pump with that. As for the existing plastic hose I will replace that as well. The existing hose does have stamped right on it "For use with builge pumps" however the 162 pipe you mentioned seems like it would be much longer lasting and stronger. Thanks for the recommendation.
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Old 01-02-2003, 03:14 AM   #6
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Default Installing 2nd bilge pump

Remember to leave enough space between the first thru hull and the new one you are going to install!

You mention that you have enough room "right next to the existing bilge exit hole".

Too close and you will weaken the fiberglass in that area.

If your thumb can fit in the opening in one fitting, and the tip of your pinky on the same hand can fit into the openeing of the second fitting, than it is TOO close. On my hand that is almost 9".

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Old 01-02-2003, 04:52 AM   #7
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Default Installing 2nd bilge pump

Keep in mind that if you tie the new pump into the existing pump, you will be pumping water back down the existing pump hose if that pump fails unless you install two check valves. I don't know if they're made for this marine application, but even if they are I wouldn't trust a valve to keep my boat afloat!
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Old 01-02-2003, 04:58 AM   #8
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Default Installing 2nd bilge pump

There was extensive discussion on this not long ago.

old fishermen never die, they just smell that way
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Old 01-02-2003, 05:30 AM   #9
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Default Installing 2nd bilge pump

IMHO, I installed a second 1100 gph in my boat with the white reinforced smooth walled that was great to use from Boaters World.
Also, each pump has it's own float switch. The second pump acts a backup for the first pump. To do this, I installed the second float switch 1/2 inch above the other one.
I didn't want both pumps to always kick on pulling more juice than necessary if one could keep up.
To test the setup, I left the plug out of the boat, backed in on the trailer and watched the bilge. The one 1100 gph pump would keep up with the volume of water on it's own without the second pump kickon on! This was the most efficient way I could think of, and it worked perfectly!
Now, if I take huge gallons over the bow, I sure feel better now since I don't have a self bailing boat.
Also, I installed the second thru hull on the opposite side of the boat. That way, I would know by looking back if I had both running, to start to be concerned!
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Old 01-02-2003, 06:01 AM   #10
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Default Installing 2nd bilge pump

Great advice given here and at the risk of repeating what some have already said, I would strongly suggest the following:
Replace original drain hose with new, smooth bore bilge hose.
Pump ratings are at zero head, so be familiar with the net output capability/capacity (after installing and routing drain hose) and size pump(s) accordingly.
Double hose clamp each end of the hose.
Install second bilge pump on opposite side of hull for visual reference.
Install the second (backup) bilge pump 1"-2" above the primary bilge pump to avoid running the backup unnecessarily. This can be done by shaping a piece of pressure treat 2"x6" board to suit the deadrise if needed. The board should be level and can be secured with 3M 5200 marine adhesive. Let the primary pump handle the casual water and draw less on your battery.
Have an idiot light on the dash, along with the remote auto/manual/on switch, to establish a visual indication when the back-up pump is running.
Route the drain lines of each bilge pump so that there is an upward loop of about a foot (or whatever you can get) before it comes back down to the thru-hull and keep the thru-hull fitting well above the waterline. This loop will prevent any intake of water from outside the hull when listing, waves, or from a beam sea.
If you have cheap plastic thru-hull fittings, replace them with good quality fittings.
Use tinned electrical marine wire throughout for much longer life and reliability.
Wire pump directly to battery to always have pumping capability on board, especially if you moor or slip your boat. Do not wire with other wiring in a way that you can turn off power to the pumps.
Enough said. Hope this helps. This is a project you will enjoy. Good luck!

2001 Seaswirl Striper 1851 DC 115 HP Ficht

[This message was edited by Nauti Buoy on 01-02-03 at 09:34 AM.]

[This message was edited by Nauti Buoy on 01-02-03 at 09:36 AM.]
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Old 01-02-2003, 06:15 AM   #11
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Default Installing 2nd bilge pump

Great advice guys...I am getting ready to do the same this offseason.

Thanks for the info.

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