back-flow on bilge pump hose

[Paul Silverman]

I just installed a rule 2000 in the bilge- it takes a hose that is 1 1/4 inches. The lift from bilge to outlet is about 4 or 5 feet. Here's the problem: the float switch is installed at the same level in the same bay between floors. The pump quickly empties the bay and the float switch turns the pump off. The hose then empties back into the bay and the switch turns the pump on. This cycle continues ad infinitim. I've considered two fixes: (1) install a check valve (rubber flap type) near the pump. (2) raise the pad that the float switch is mounted on so that the switch does not turn on when the water remaining in the hose empties back into the bilge. Disadvantage of #1 is that rule does not recommend installation of a check valve in the line. Disadvantage of #2 is that I end up with a few inches of water (fresh water!) permanently in the bilge. Opinions?

[Ken Hutchins]

An option is a relatively large cross section, but shallow storage tank with another pump in it. Use a switch with a lot of travel. This has the advantage of having another pump in case of a clogged screen or other failure of the first pump.

Edited to correct tank description and add switch info.

[ 07-03-2005, 08:12 PM: Message edited by: Ken Hutchins ]

[Gary E]

Why a 5 ft head? Is the bilge water level that far below the boats waterline?

If you can move the outlet to just above the water line how far much head is there? allow a little loop to provide an antisyphon feature.

If all that is not possible, install a 3/4" pump and set it to do the normal pumping and set the float switch on this high capacity pump higher as a high water pump only amd include an alarm to tell you that it is on.


The pump quickly empties the bay and the float switch turns the pump off. Are the ajoining bays still full of water? if so fix that so they drain rapidy to the bay that the pump is in.

[ 07-03-2005, 08:57 PM: Message edited by: Gary E ]

[Bob Cleek]

Oh for Pete's sake guys! Talk about reinventing the wheel. All that needs to be done is to install a check valve in the bilge pump line. Rule and Whale make them. They are sold anywhere you buy the pumps because this is a very common problem and these in-line valves are made to solve it. Every bilge pump should have one. They cost about eight bucks as I recall.

[John B]

This is how I learnt about non return valves for the bilge pump. Mine is rule 2000 for the record too.
Picture the boat .. 1907 counter stern yacht. like all 90 yr olds , she might leak a bit from time to time. The bilge pump hose runs up to the deck level and out the counter to within about 2 ft of the stern so its well above W/L.

Soooo annnnyway, we're motor sailing off about 25 or 30 miles to Kawau island one friday night and Kirsty thinks she'll give the pump a blip while we're going along ,except she turns it on and forgets it. Because the motor is on we don't notice the noise of the pump,So its on running dry for 1/2 an hour or so until ooops , pump is still on , turn it off.
See here's the thing, at 7 knots the Waterline is increased by about 5 ft and the hull wave follows the counter right up to the transom. By turning the pump on and off at the speed we were doing, we set up a syphon and we filled the boat to the level of the sole before noticing. ;) No biggy in itself but illuminating.
I fitted a non return valve after that.

[Paul Fitzgerald]

Bobs right, my bilge stainers come with the non return valve built in.

[Ian McColgin]

Besides the non-return valve, even a pump with the discharge above the normal waterline should have a high vented loop to deterr syphoning.

I could be induced to have an auto-pump if I ever did not live-aboard and/or did not check or use the boat at least weekly, but that aside, I much preferr a good diaphram pump like an Edson. Part of watch change becomes pumping, counting the strokes (realily convertable to gallons) and logging it. That way, few surprises.

Grana had three watertight bays. Rather than one pump and a manifold I decided on three pumps to give a little redundancy.

Anyway, I don't like electric pumps unless the system has a light and minutes counter so's you know what's up.

We've all seen what happens when the bilge reaches the orlop.

G'luck

[Paul Silverman]

Thanks. I'll install the check valve. The head may be around 4 feet- total draft is 5 feet and the outlet is about a foot above the waterline. There's no room for a storage tank or for a hose loop that would be effective. There are limber holes on each floor, but the constant cycling still will happen.

[formerlyknownasprince]

I'm with Gary - I've installed a second, much smaller, pump which is in the lowest possible part of the boat - on the garboard, about 3/4" below the main pump which sits on the keel. It made quite a difference to the water level in the bilge, as the larger pump doesn't get anywhere near as much water out.

Ian

[Andrew Craig-Bennett]

I'm with Ian; I will not have an electric bilge pump.

[Dan McCosh]

The check valve would solve the cycling problem. I'd also note that keeping the pump inlet covered by a couple of inches of water prevents any oil that that gets into the bilge from being pumped over the side. This is becoming a larger issue today due to the stiff penalties for such discharge. As an aside on keeping track of the pumping--our electric pump discharges into the cockpit drain, and it is clearly audible when it kicks on.

[Ian McColgin]

Because a check valve can be kept open by any bit of bilge debris that gets past the strum box, an insurance survey of average care will deny coverage to a boat where the bilge pumps do not have an anti-syphon loop and valve.