Installing Secondary Bilge Pump and Alarm

kappykaplan · Jul 13, 2015

New bilge pump should have its own dedicated discharge line.

Chief RA · Jul 13, 2015

I would hook in the existing hose as you have already stated its for redundancy. Chief

kappykaplan · Jul 13, 2015

So what if the primary discharge fails and both bilge pumps are trying to exhaust liquid through the same failed hose/overboard discharge? That is not redundant. I have a secondary bilge pump on my boat, and it has its own dedicated discharge.

kappykaplan · Jul 13, 2015

My recommendation is a new dedicated discharge line.

Chief RA · Jul 13, 2015

Over reaction to such things can create an additional problem. When do we decide that if we put the boat on the hard we won't have to worry about a bilge pump or two at all? Remember, he stated the 2nd pump is 6" higher than the other one, not a parallel simultaneous load. One quality hose, one hole in hull. Chief

Chief RA · Jul 13, 2015

Doc: 2nd pump is wise, I just didn't cut another hole when I did this, as, like you, my pumps are at different elevation. Chief

Kings Gambit · Jul 13, 2015

It depends on what you want the secondary bilge pump to do, or envision it to do. If to help dewater the boat in a emergency situation it needs its own discharge hose so the boat can be dewatered from two locations. Supposedly then, the second pump would be in a different location than the first one. If you wish redundancy (back up), where the second one kicks in when the first one fails and the water rises to that second level, then what you suggest might be OK but the "professsionals" would not like it. Clearly, if the 1st one has failed it will not be pumping water at the same time as the back up. But it sounds to me that what you really want is to be able to circumvent a defective float switch if necessary. Install a 3-way switch to the existing bilge pump where if the float switch fails, you can still activate the pump directely by flipping the switch from "stand-by" (float-activated pumping) to "on" direct activation. Also, put in the alarm so you (and your neighbors) will know if the water is rising but not being pumped out. BTW, I check the float switch on the Bavaria at least monthly to make sure it's operable--usually when I leave the boat for some period of time.

Sailvayu · Jul 13, 2015

What if the first pump fails because the hose is glogged, That second pump will also be useless sharing a clogged hose. And what if you are taking on water and need both pumps, you can only push so much water through the same hose.

https://youtu.be/Fcbd41iDe2Y

Chief RA · Jul 13, 2015

Skippers decision now. Chief

Benny17441 · Jul 13, 2015

The proper way is to install the back up pump is with a separate discharge line and port. To use a single discharge line you will need a check valve but the problem is that check valves are not recommended to be used in the bilge as they are prone to fouling. A fouled check valve will allow the discharge of pump #1 to flow through pump #2 (path of least resistance) back into the bilge. My opinion on electric bilge pumps is that they are the greatest convenience item put on a boat; it automatically discharges incidental water that accumulates in the bilge even when I'm not present. My opinion on 2nd or backup pumps is that they are OK to save the woodwork in the cabin sole but neither can be considered a safety item as they will quickly be overwhelmed by any significant inflow of water. On the other hand utilizing a check valve will not be a significant safety hazard other than for the woodwork. If I were taking the boat offshore I would insist on separate discharge lines but for lake and coastal cruising a single one would do. Choose your poison.

woodster · Jul 14, 2015

Bowedtoothdoc said:
Thanks Everyone for the input. I am going to try to run a separate discharge line if I am able to. Does anyone have recommendations as to the sizes of the various pumps for a 45ft boat? Also thanks for the link to Capt. Wayne's video!

i have a 750 gal pump 3/4 hose for primary and a 1500 pump 1 1/8 hose for secondary mounted about 12 inches above the primary.....and a 1 1/2 inch manual pump ...make sure your manual pump is in good working order and when all else fails i have a second manual pump mounted on a board that is portable just incase can't have enough bilge pumps

MrBill_FLL · Jul 14, 2015

the high water pump is usually much much larger capacity. -be sure you can turn off that alarm. -hard to think straight with that alarm in the middle of a crisis.

*if it gets that high, you have a serious problem.

(.02)

Chris Patterson · Jul 14, 2015

I've also got a high water alarm in the boat. It also has a kill switch on it as well. If you've ever been in a plane with the master caution or warning go off you'd see what I mean. It's hard to concentrate when that racket is going on..

Benny17441 · Jul 16, 2015

I would not worry to much about the size of the bilge pump in a 45 ft boat. It is the sailor in a 22 footer that needs the larger pump as the boat will fill up much faster. I would be happy with a 750 GPH pump. Check what you have now as the size of the discharge hose could differ if you go to a larger pump.

Sailor Sue · Jul 19, 2015

You might want to rethink this

A member of our club just had a very interesting experience. He was motoring his 50 foot Gulfstar with 2 other friends when they apparently hit a submerged log or deadhead - they're not sure exactly what happened. At any rate, 3 of the 4 bolts holding the prop shaft to the transmission sheared so the shaft's eccentric motion cracked the shaft log. When he noticed the inrush of water he turned on the electric bilge pump. I have no idea of the capacity or condition of the electric pump but it couldn't keep up with the flow. The three of them spent the next 2 hours taking 10 minute shifts on the manual pump while waiting for a tow to get hauled out.

This confirms my thought that you want a larger pump rather than the cheapest one. On our last two boats we have fitted 2000 gph pumps 4 or 5 inches above the 500 or 800 gph pumps the boats originally had. The 2000 gph pumps have/had their own discharge hose and wiring. Also have a manual pump in the cockpit.

Chief RA · Jul 19, 2015

A larger pump may pump more water (if the hose is large enough) but will run your battery bank down fast. In your example you better be onboard and crank up the engine as just your 1 big pump will draw about 2.5 times as much current plus the little ones current draw. (est. 12a)
Larger may not always be best! Chief