Important - Bilge Pump Alert!

[Rob]

Ah - where to start....After an afternoon sail today, I did a routine check on my bilge pump (1 year old) and found it was not functioning. Luckily, my bilge is relatively dry (I have an A-4) and I rarely, if ever, see it pump out. Nonetheless, I like to know that the pump is up to its task, so I dump a bucket of water into the bilge once a month or so, and watch the pump go at it. Today, it failed completely. I am writing this post to warn you of a possible problem that may exist on your boat if you have my type of pump.The pump in question is a Rule 500 Platinum. It is a self contained unit, which does not use a float switch. It operates by spinning up once every 10 minutes. If the impeller senses no resistance, it cycles off, and waits another 10 minutes before checking again. If it DOES sense resistance, which it assumes is water, it runs until the water is pumped out and no water is left to offer resistance. It then goes into alert mode, cycling every 2 minutes for the next 10 cycles, and then returning to cycling every 10 minutes. A sound principal in theory, but here is its Achilles heel.If water enters the boat somewhat suddenly (such as a broken hose), an air bubble can (and frequently does) form around the impellar, causing the impeller, when it spins, to spin in air, not water. In other words, the bubble keeps the water away from the impeller, and the processor on the bilge pump senses no resistance, which SHUTS THE PUMP DOWN AS WATER CONTINUES TO FILL THE BILGE.I know this sounds a little alarmist, so I performed a test. I disconnected the pump from the battery, and reconnected it to force it to start cycling. I did this over 20 times without the pump drawing water (even though it was completely submerged). Doing a rough calculation based on the pumps cycle times revealed that the boat would have taken on water for almost an hour - and at the end of the test, the pump still was not pushing water out of the boat.I am of the opinion that this type of pump has a design problem. Has anyone else experienced this?As always, your opinions and experiences are greatly appreciated.Best Regards, Rob Rich

 

[Steve O.]

design problem alright

The problem is the darn thing is too complicated and has too many ways to go south on you. I'd go back to the old-fashioned float switch type.

 

[Don Evans]

Thanks Rob...

But any pump is only as good as the batt that its attached too and if your not there lets hope somebody notices the continual stream of water before your batt drains down.To help, my father in law rigged up a high water alarm and a car horn to his boat bilge. What a wracket when it goes off (I tried it once). It hopefully draws attention to your boat. I'm considering rigging one up to my boat as it is moored in a fairly low traffic docking area. Somebody may not notice the problem. I give complete permision for anyone to break in to my boat and rescue her if she is sinking at the dock and have signs affixed stating to call me collect if a problem is noticed.Don

 

[Jim Hague]

Great post

Great 'writeup' Rob. I've seen other pumps become airlocked like you describe. However, they were all external-switch models.

 

[Mike Kenny]

Seems like it needs a vent.

After reading your post, I initially thought adding a float switch at a higher level could be a quick and easy solution offering redundancy. Kind of a 'belt and suspenders' approach. Although, after a little further thought, the pump is already cycling without disturbing the air pocket. An auxiliary float switch is not likely to help.Your pump needs some form of vent at the impeller to prevent an air pocket from ever forming. Perhaps it has one that has become clogged?

 

[David]

MINE JUST QUIT

After less than a year, my rule automatic 1100 just quit. As have the other 4 rules in the last 4 years. They suck. But I can't find an alternative

 

[Rob R.]

Mike - good question

I'll check into it and report back. My initial thought is that a vent would cause the pump to "suck air" and de-prime itself, unless the vent had a valve to prevent that. If it doesn't, I think we just found a million dollar idea!Rob