High water Bilge pump capacity?

J

jmunro123

Member
Feb 2, 2008
370
Gran Bend, Great Lakes
Boat Info
2004 Sea Ray 390 Motor Yacht
Engines
8.1's
WHAT IS THE WORST HOLE YOU HAVE EVERY PUT IN YOUR BOAT AND DID THE PUMPS KEEP UP?

On our boat it has 3 bilge pumps
aft 1,500 gph
aft 1,100 gph
mid 1,100 gph
for a total of 3,700 gph

I have read that a boat this size should have almost twice that volume?
 
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it says on pump itself.
you probably have a RULE pump and number on pump
(800, 900, 1000, 1200....) tells how many gallons per hour pump is capable of.
 
Those are the pump ratings w/o any restrictions, like hoses or fittings.

When hoses are added, the actual rate decreases.
 
jmunro123 said:
I have read that a boat this size should have almost twice that volume?
Click to expand...

Let me guess who wrote that. David Pascoe.

David is knowledgeable however he assumes every boater is going well offshore. He would scoff at the very boats you and I own, regardless of their onboard safety items.

Keep your current bilge pumps, test them to verify they work on a regular basis and carry onboard a variety or corks to pound into a hole.
Corks should be large enough to fill any thru-hull you have.

If you are going offshore, have a life raft + EPIRB.
 
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jmunro123 said:
how much would a 2 inch hole allow into the boat? Any ideas?
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I’m sure Gary will be able to provide a formula.

To answer your question we also need to know the depth of the hole.

A 2” hole at the water line will let in a lot less water than a 2” hole at the very bottom of your hull.

Say your transducer fell out. That would let in a lot of water.


Again, the idea is not to have sufficient pumps to keep up with all possibilities, it’s to detect the issue early, have onboard the necessary items to fix it and have a life raft.


Say you have outdrives and your gimbal breaks. Your drive will fall off, leaving a big hole. I’m not sure you could pump fast enough no matter what.
 
it looks like a 2inch hole 3 feet down will let in 20,000 gph of water.

Basically, the pumps will just give you more time make a tem fix or to hit the DSC button, get the lifejackets on and get the tender deployed.

Sea Gull - what did you put in the search field to get find that thread?
 
The water let in by a hole increases exponentially the further down it is from waterline (others already mentioned this).

Also, keep in mind the rated GPH is under controlled evnironments. Yours may vary by battery power, age of pumps (& impellers), blockage in the bilge, etc.

But you can test it (BE CAREFUL - some wouldn't recommend this)

Put one end of a hose in the water - attache a weight to it.
Take the other end, and jump inside your bilge. By keeping the hose at the water line, you can watch to see how quickly your bilge fills ane empties. If it's too much water, just lift the hose up.

If that test doesn't sink your boat, you can try again, putting the hose further down from the water line.
 
jmunro123 said:
it looks like a 2inch hole 3 feet down will let in 20,000 gph of water.

Basically, the pumps will just give you more time make a tem fix or to hit the DSC button, get the lifejackets on and get the tender deployed.

Sea Gull - what did you put in the search field to get find that thread?
Click to expand...

Look for the highlighted words when you follow the link. It looks like he used "hole" and maybe a Name that he knew to have posted in the thread. I search with my name a lot to find old threads that I have posted to.
 
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