Dribble pump...

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stmbtwle

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Had occasion to drop my rudder today for inspection (ran aground last weekend). The top of the 1-1/4" stuffing box is maybe 3" below the waterline, and one wouldn't expect a big problem from the water that came in.

Well, the little 500 gph primary pump could NOT keep up with the flow; it wasn't but a minute or so before the larger 1200 "backup" pump kicked in to pump out the balance. The big 4000 "crash" pump never came on.

So for those that think a little 500 pump is "enough", think again!!!
 
500 gal/hour is only 8.34g/minute. And that is measured at full voltage, with zero ( 0 ) head ( lift ). You should always de-rate these numbers to account for head and usually to account for lower voltage, as well. ( and commonly, de-rate for corrugated hose, as well. Yecch. lousy stuff for pumps! )

In short, that pump, in actual use is going to deliver closer to 4 or 5 gpm. That means that is can handle a bit of minor deck hatch leakage from spray or rain. It is not nearly enough for an actual hole in the hull. Upgrading the bilge pumps is likely appropriate for -every- boat ( as delivered new ) because that is one area where mfgrs "meet the regs, not the needs".

Can pumps save you from sinking? Perhaps, if the leak is "small" such as a shaft pulled out of place, but you need substantially more pump capacity than I have ever seen as "standard equipment".

btw: Even if is does not actually stop the boat from sinking, it will give you more time prior to abandonment or time to find and plug the hole. Pumps are useful, but you need sufficient capacity to make them useful.

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Several posters will recommend rather substantial dedicated "crash pumps". These are a good thing, but in smaller boats, impractical. Upgrading the pumps can be useful to all.
 
Can pumps stop you from sinking? It all depends on the leak. IMO compartmentation is a better solution but not found often on pleasure boats. Alarms are essential as they give you more warning and the opportunity to do some damage control. When the engine drowns out it's too late.

I rely on the 500 gph pumps strictly for rain leakage, condensation and shaft "dribble" and they do a good job at that. They're cheap, easy on batteries and float switches and can dry your bilge out better than a bigger pump; but they're simply not big enough for any kind of leak. IMO you need at least two pumps per compartment and an alarm.
 
I have 3 Rule pumps on my tug.
1. 1500gph
2. 1200gph backup
3. 500gph for the shower drain

If that doesn't save me ?? Let the old girl sink then. :)
 
When we had our Chaparral surveyed before its puchase, the surveyer showed us the 375 GPH bilge pump. I called it a joke, not a pump. His comment to me was interesting. Basically, he said, the job of a bilge pump is to get rid of rain water and spray. In a real emergency, it will only hold off the sinking long enough to call for help and evaculate. I have replaced the pump with a 2000 GPH pump. Food for thought. Hy
 
My bass boat came with a 500 gph with no float switch. After a near sinking at a dock in a rain storm (South Florida) I upgraded to a 1000 with a 750 backup, both on floats and hooked to different batteries with the float switches straight from the batteries, NO switches to accidently turn off. 20 amp fuses which are way to big for the load but I figure they'll blow before a fire starts and I want to be sure they'll pump.
 
As the surveyor said the small pump's job is to remove rainwater. As far as giving you "extra time" a pump that size isn't going to make much difference if you have a leak. As I mentioned the water coming in through the rudder stuffing box (only a couple inches below the W/L) was enough to overwhelm a 500.

Having multiple pumps on multiple batteries is a good idea, as it's possible for a pump to drain the battery and THEN the boat sink. However without some attention the SECOND battery will die from the same cause. You still need an alarm to "get your attention", either on it's own float switch or connected to the second pump.
 
Why would you have a smaller backup than the primary pump? If the primary isn't keeping up then the backup being smaller surely won't. I would thing you have them backwards, as the secondary is to do what the primary won't.

I don't have this question on mine as both are 2000 gph Rules with a 750 shower sump that also deals with A/C condensate
quote:
Originally posted by way577

I have 3 Rule pumps on my tug.
1. 1500gph
2. 1200gph backup
3. 500gph for the shower drain

If that doesn't save me ?? Let the old girl sink then. :)

Click to expand...
 
In my bass boat I put the biggest pump I could fit as low as I could and then the other one is higher and, again, I run into space issues. And how many 1" holes I want to add. The 750 is hooked to a 3/4" that was where the original 500 was. I added a 1" for the 1000 and decided that it should be primary and I didn't want another 1" hole.
 
"Why would you have a smaller backup than the primary pump? If the primary isn't keeping up then the backup being smaller surely won't. I would thing you have them backwards, as the secondary is to do what the primary won't."

Bear in mind that if the 1500 "primary" can't handle the flow, with the 1200 "backup" running as well the rate is nearly doubled. It's not like you turn the primary off.

On my boat the 1200 "backup" IS larger than the 500 "primary" pump, by more than double. So with both of them running the rate is (at least theoretically) TRIPLED. If the 4000 "crash" pump ever kicks in the rate is tripled again. Even if I downrate them all by 50%, that's still nearly 50 gallons/minute.
 
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