Bilge Pump, Loop & Water Discharge

RWS

RWS

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Given:
.
rear bilge pump thru hull is partially or completely covered (submerged)due to overload
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and
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loop from that bilge pump is well above the water line
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will that bilge pump still be able to pump water and discharge it from the boat, as long as that loop remains higher than the water line?

Inquiring minds, you know.....

RWS
 
I don't think the answer is simple. Depends on type of pump, total head up to loop and depth of through hull. Seems to me though that back flow at pump shut off turns this into a siphon if it's not a positive displacement pump. Am I wrong?
 
Definitely not a good set-up. You're forcing water out against all the water on the outside. Depending on the pump, you may have negative bail. If the hose, coupler, or fitting fails, your boat will sink. You need to reconsider the boat's loading and/or install a thru-hull higher up on the side of the boat, securely closing the present thru-hull. If it were me, I'd be looking to lighten the boat's load. By over-loading the boat, you're affecting its safety and its handling and probably making yourself legally liable if anything happens. hy
 
Yes it might pump water but it also can create a nice siphon into the boat.
 
quote:
Originally posted by pdecat

Yes it might pump water but it also can create a nice siphon into the boat.

Click to expand...


So put a siphon breaker vented loop like Forespar makes at the top of the hose loop. As long as that is never below the waterline, you're good to go. Lots of overboard discharges are designed to work when the boat heels and the outlet is below the water line. Used all the time on macerator pump discharges.
 
+ 1

quote:
Originally posted by caltexfla

quote:
Originally posted by pdecat

Yes it might pump water but it also can create a nice siphon into the boat.

Click to expand...


So put a siphon breaker vented loop like Forespar makes at the top of the hose loop. As long as that is never below the waterline, you're good to go. Lots of overboard discharges are designed to work when the boat heels and the outlet is below the water line. Used all the time on macerator pump discharges.

Click to expand...
 
yes a siphon breaker is a good idea and it might work if the check valve in the breaker does not stick open. Holding tank systems are mostly closed and have check valves while bilge pumps often do not. IMO holding systems are unlikely to sink a boat while open bilge pumps are a different story.
if this is a trailered or lift stored boat then someone would be onboard when it was in the water. If it is water stored and unattended I think it should be fixed. Insurance might even refuse coverage due to negligence, just my opinion.
 
RWS, why the overload? Did you add something new?

Is your boat bottom painted and in the water, or do you have a lift?

Is your friend still selling his repowered 36, or is it already gone?
 
it will pump fine but chances are that as others have mention you may syphon water back in and possibly sink the boat. A syphon break will do he trick but if that TH is permanently below water line, I would move it higher. You can probably do this while in the water by using weight to temporarily give the boat a list.

Three concerns about having it underwater...

- you don't have a seacock, required on below waterline fitting
- hose may not be rated for being under waterline, most builders used cheap ribbed garbage
- is it double clamped?
- if the TH is metal, is it bonded? If plastic is it cooked by the UV and could it crack. I ve seen it happen.

Oops... That s four...
 
Thanks Guys, !

actually it's NOT MY BOAT.

Someone asked me the question regarding running in the protected canal portion of our 7 mile boat parade.

http://www.puntagordaboatparade.com/2012_Parade_Route.pdf

In addition to your comments, I told him to have adequate life vests on board, good insurance and a great attorney to represent him, should the need arise.

RWS
 
I dunno - when someone starts a sentence, "Hey, if on my overloaded boat, I have xxxx . .." isn't that kinda like that long, lost red-neck relative you once had, whose last words were, "Hey everybody, let's see what happends when I do this . ...!"
 
"HOLD MY BEER AND WATCH THIS........."
 
There was a thread here a few months ago about an overloaded boat that CAPSIZED, killing several children...

The bilge pump may be the least of your worries.
 
You all are missing the point! Its not the owner's fault for operating an overloaded boat - its the manufacturer's fault for failing to put a label on the boat indicating that overloading could cause the through hull to be submerged and if something breaks, water could enter and sink the boat. And it is probably also the government's fault for not requiring the label.

After all, wasn't that the defense in the Long Island case referred to by STMBTWLE. Silverton failed to let the owner know that 27 or so people on a 34' Silverton is too much.

Whatever happened to common sense. If it was designed to be above the waterline and is now below it, something bad is possibly going to happen. As is said, you pay your money and take your chance!
 
Agreed. Common sense should tell one that when an over-water thru-hull is underwater, something is wrong and should be changed - with the boat's loading, not with the thru-hull. Hopefully, RWS or the boat owner he's discussed (assuming it's not him and his boat) will realize the error in his ways and correct the situation before we read of another boating tragedy. I've met a fiend of the owner of the Silverton which sunk, causing the death of those three children. The family, according to him, still thinks they did nothing wrong and it was just a tragic accident caused by a rogue wave. Sometimes common sense isn't that common. Hopefully, a second such event can be prevented by this thread. Hy
 
quote:
Originally posted by pdecat

yes a siphon breaker is a good idea and it might work if the check valve in the breaker does not stick open. Holding tank systems are mostly closed and have check valves while bilge pumps often do not. IMO holding systems are unlikely to sink a boat while open bilge pumps are a different story.

Click to expand...


I don't recall seeing a holding tank discharge with a check valve, it would be a quick candidate to get gummed up. Vented loops yes, and still you have to maintain those for clogging the valve. Many holding tank macerator pump discharges are permanently under water and so the threat of flooding is very real.

But I should have made myself clearer and was wrong not to do so. Overboard bilge discharges should not be underwater on an ongoing basis. A simple gently curved bight of the hose extending well above the maximum heeled water line of the boat should be adequate and keep complication to a bare minimum.
 
What's this thing you call "common sense"? Are you sure you didn't mis-spell some other phrase?
 
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