Could my bilge pump thru hull siphon back?

[danstanford]

2000 Hunter 290. Been almost bone dry through the month we have sailed her...we think!

Did a couple of hours on a blistering starboard tack this afternoon with the rail almost in the water and had a blast. Until my Bride went below and hollered that we had water over the floorboards! The bilge pump would only come on when I held the override switch which I did till we got the water down to a manageable level. The bilge pump was not working normally on the float switch but would work with the override. Could the siphon start if the bilge pump wasn't working?

We cannot find any place else other than the galley sink which has a frozen sea cock, but we couldn't see where it would have pumped water in as the area around and under the sink seemed dry. After getting her dried out it appears that the water is not getting in any place else though we did notice quite an odour from the holding tank though it was pumped out recently and has had only a couple of liquid flushes. The galley and the bilge pump through hull are both on the port side while the other thru hulls are all on the starboard side which certainly did not give us any problems after we tacked. On reflection, I wish I had kept her on the starboard tack till I figured out where the water was coming in but all I could think of was getting it out and stopping it from coming in!

Any ideas? Dan

 

[njlarry]

To siphon the discharge port would have to be below the waterline. Most are on the transom so that can not happen. If it is below the waterline it needs an anti siphon loop. More likely you have a leak on the starboard side.
I would replace that sink seacock as that baby can flood you fast.

 

[danstanford]

Larry, the discharge is about mid-ship on the port side and would have been under water for a couple of hours because of the starboard tack, it would normally be 18-24" above the water line when she is sitting level.

I didn't look for an anti-siphon loop and it wasn't easy to do so because of where it goes up under the floor and behind the cabinets/wall panels but I will.

Still wondering if the issue has been in place before but been short enough in duration that the bilge pump dealt with it and either the pump burned out this time trying to cope or that the issue only became obvious because the pump quit.

Does it make any sense other than a bad float switch that the pump would work on override but not normally? I triggered the float switch manually and it wasn't stuck but otherwise had no way to test. Do they have two systems or just two ways to switch on?

Thanks for the feedback, Dan

 

[Ken Cross]

Could your heeling been sufficient to keep the float switch from working? I suspect the float switch is designed for vertical mounting.

Ken

 

[Capt jgw]

I'm not clear on whether the pump came on when you lifted the float. If it did there's nothing wrong with it. The angle of heel could have jammed the switch so it wouldn't lift, they'll only tolerate so much angle. Water definatly can siphon in if the outlet goes below water. I've had that happen in the same type situation.

 

[danstanford]

The switch was bad and so I replaced the whole mess with a new pump. I have had her heeled over this far before on both tacks and never noticed any problem. I now wonder if the only problem I had was the bad switch. My stuffing box is dripping at over 40 drips per minute at rest with no shaft rotation so if the pump was not pumping perhaps the water was just under the sole in the marina and only became evident when she heeled over.

Now that I have a shiny clean bilge I will take her out and heel her over and go through the systems to see if I get any water. Oh, and I will tighten up that stuffing box too!

Dan

 

[njlarry]

If your discharge is ever going to be below the waterline make sure that it has a vent loop. I would not count on any electric bilge pump working. I'm sure you know to mount the float switch fore anf aft so that it will not be affected by heel.
My next switch will be the non mechanical type.

 

[Pat]

Dan, on our O'day, we had a hose come off the galley faucet and the water switch was on so it emptied the
water tank on the teak and holly floor....this happened twice....then one time later, we again had water on the floor
and had been pretty well heeled over for a while, but that time we found out the 30 gal tank had a hairline crack and when
heeled to starboard, the tank leaked.....good luck...and yes, the bilge pump can send some water back into the bilge.
but you want to make sure, your pump sensor is low enough that this backflow is limited.....good luck, Patrick

 

[uncledom]

I'm a big fan of the Water Witch electronic bilge switch which happens to be available right here on SBO.

 

[danstanford]

I finally got the thru hull for the galley sink drain to operate now that I have her on the hard so we can eliminate that as an issue but I have not yet found a way to tell if I have an anti siphon loop in the bilge pump discharge line as it is behind cabinets and panels at the end of the galley. No more water in the boat after I fixed the bilge pump switch and tightened up the drive shaft seal so I think I am now mostly in control.
In the end I think the leaky seal dripped into the bilge and since the pump switch was broken the bilge filled up to just under the sole which didn't show up till we were heeled over. The misleading part was the fact that we had turned on the electronics while at the dock and then nobody went below for more than an hour which made it seem like the water was suddenly there.

Thanks for the input folks!
Dan

 

[Ken13559]

could it be the bilge water was collected over time instead of from the heeling? Same thing happens to mine. Didn't notice bilge level till boat heels and water wets the floor rug. Pump didn't work probably for some time as bilge was slimmy like kept water for months! Didn't notice there be vent on discharge hose but hose rises up above discharge thru-hull.

 

[Ken13559]

Dan, good that you found the "bugs".

 

[danstanford]

Ken, you nailed it. The bilge pump switch had quit and the persistent drip at the stuffing box filled her up to just under the sole. Finding it at the dock would have been better than half way across a Great Lake though!

 

[Maine Sail]

Larry, the discharge is about mid-ship on the port side and would have been under water for a couple of hours because of the starboard tack, it would normally be 18-24" above the water line when she is sitting level.

This is just a poor design decision by the builder or the installer who installed it. A bilge pump discharge port, that can go below max heeled waterline, yet does not have the height for a siphon break AND a proper seacock, should not be installed on a sailboat.

The proper location for bilge discharge on a sail boat is above the maximum heeled waterline in an area that area does not dip below the discharge port when under sail.

The answer is yes your bilge pump system can siphon especially if it has been designed in a poor fashion......

A few things, such as water above the floor boards, could have been avoided if the vessel had been built to the meet the applicable safety standards:

"22.7.3 On boats with an enclosed accommodation compartment, an audible alarm shall be installed indicating that bilge water is approaching the maximum bilge water level.

22.8.6 The discharge location shall be above the maximum heeled waterline, or

22.8.7 the discharge may be located below the maximum heeled waterline if the discharge line is provided with both of the following:

22.8.7.1 a seacock installed in accordance with the requirements of ABYC H-27, Seacocks, Thru-Hull Connections, and Drain Plugs, and

22.8.7.2 a vented loop or other means to prevent siphoning into the boat. A check valve shall not be used for this purpose."

With safety standards it is usually best to not build to the "or" part which are "exceptions to the rule"....

 

[FastOlson]

Looks like the problem was found and (hopefully) fixed. One factor that was not focused on was the pump itself.
Production boats at the bargain end of the spectrum usually have centrifugal pumps, like the ubiquitous Rule.
Under just the right conditions, they can move a lot of water for their size and cost. Unfortunately they are almost never installed without moderate to severe compromise in the discharge piping.

And... without a high enough anti-syphon loop they will back-syphon readily. A long time ago, I discovered this problem on our boat. I was replacing a deceased original ITT Jabsco chamber-type pump and was seduced by the GPM hype for the Rule. Later, after experiencing the back-syphon failure (with about five gallons of water wandering around our shallow bilge (after sailing for quite a while at enough speed to submerge the transom thru hulls) and really reading up on the reduced GPM problem with a long hose run, I spent the extra $ for a new ITT-Jabsco 37202-0000. These do not back-syphon. The factory guys @ Ericson got it right the first time.

Oh yeah, on the subject of switches..... I would swear that those little float switches have a programed-in failure point of about 5 years, whether ever actually activated or not! How such a simple "rolling ball" device could be so cheesy is a wonderment. Yes, I do lift each float by hand to test them several times a season.

Regards,
Loren

 

[Maine Sail]

I was replacing a deceased original ITT Jabsco chamber-type pump and was seduced by the GPM hype for the Rule. Later, after experiencing the back-syphon failure (with about five gallons of water wandering around our shallow bilge (after sailing for quite a while at enough speed to submerge the transom thru hulls) and really reading up on the reduced GPM problem with a long hose run, I spent the extra $ for a new ITT-Jabsco 37202-0000. These do not back-syphon. The factory guys @ Ericson got it right the first time.

Centrifugal pump ratings are pure hog wash as installed and used! In my opinion EVERY BOAT should have a high capacity centrifugal "oh $hit pump" (in excess of the 2000 GPH Disney fantasy rating) AND a diaphragm pump for dealing nuisance water. Builders are cheap but the good builders still install diaphragm pumps.

Oh yeah, on the subject of switches..... I would swear that those little float switches have a programed-in failure point of about 5 years, whether ever actually activated or not! How such a simple "rolling ball" device could be so cheesy is a wonderment. Yes, I do lift each float by hand to test them several times a season.

Regards,
Loren

Five years was pretty true back when mercury switches were used, today it is more like a few weeks to a few months.... The only switches I install these days are the ones made by Ultra Safety Systems. I know a lot of people recommend the Water Witch but I have had quite a few issues with those switches. The best bilge switch, the one I have & use on my own boat, was unfortunately discontinued because NO ONE was willing to pay for the quality.

If boaters continue to demand cheap crap, they will continue to get cheap crap. IMHO none of the centrifugal pumps are worth the packaging material they ship in. I am glad I bought a spare for my bilge switch because I might need it in oh, 30 years..... My savings on bilge switches will continue to fund a new centrifugal pump every 1-2 years...

BTW my last diaphragm pump was from 1982 and was still going strong when I replaced it. It was just getting a bit rusty so I yanked it, but it was still purring along beautifully and pumping water like crazy. The boat has had no less than a dozen centrifugal pumps in that same 31 year time frame.

A well designed electric bilge pump system would always include one high capacity centrifugal and one diaphragm pump, at a bare minimum. Sadly most boaters don't take their bilge pumping systems as seriously as the really should and continue to accept the lies and deceit force fed to them by centrifugal pump makers.

Rant off...

 

[woodster]

i have one like this on my high water pump

 

[Ken13559]

with this frightening experience of "flooding" I've ordered a new bilge pump and a bilge level alarm.