need a "Skip Experiment"

[brackish]

Still struggling with where to put a hole for my output hose for my auto bilge pump.  As I recall, Skip lets his share the same outlet as his manual pump (with a wye?).  While this is not considered best practice and the normal "expert"advice is to not do it, I wonder if an experiment is called for. Condition one, timed pump into a bucket electric bilge pump. Condition two,same thing manual pump.  Condition three, both at the same time.  Does one plus two equal three water volume speaking?  Is there any backflow into the either pumps line when the other is only being used?  inquiring minds and all that...really would like to avoid drilling another hole.

[CaptRon28]

Most electric bilge pumps will allow the seawater remaining in the output line to drain back into the bilge after the pump shuts down. I've noticed that on several boats with varying sizes of bilge pumps, which makes it nearly impossible to pump the bilge dry. A check valve could stop or reduce this, but they tend to reduce the flow, and are unreliable. Loops won't help either. Never tried it, but I assume if the manual and electric pumps use the same through-hull and there are no check valves on either side, then either or both could allow some of the seawater back into the bilge while the other pump is being used.

It's not a great idea, but I've used a sink drain in the past. But make sure the loop goes well above the water line. Best way is to break out the electric drill with the appropriate hole saw. Not a bad job either. These hulls are solid fiberglass.

[skip1930]

1~Back flow valve is part of the 5 gpm Gusher manual pump. No water will flow back past this manual pump as long as the 750 gph El Pump hose is down stream.

2~So a tee in the cut line down stream of the pump is fine. I won't care if the water runs up to the manual pump. So what?

3~Water will flow only at 33 feet per minute through a hose. Were talking 6-1/4 gallons per minute max flow. I think we have OK hose diameter to flow 6-1/4 gallons/min.

4~The 'Sea Water' has to splash past the factory flapper valve in the transom and flow up hill to flood over to the manual pump and back track out the electric pump.

5~Typically the hand pump discharge line is way above the hull water line. Even above the cockpit floor. It's just below the settee hatch.

6~Granted the electric pump has no back flow valve but the 'Sea Water' has to flow up hill from the scupper in the transom.

7~I understand your point about routing the tube from the el. pump. It's an acceptable risk me thinks.

8~One plus two equal three? Yep. It does.

9~The literature of this electric pump says the pump continues to run for x?x amount of seconds after the float see's no more water. This helps clear the lines and impeller housing of pumped water. So the statement "Most electric bilge pumps will allow the seawater remaining in the output line to drain back into the bilge after the pump shuts down. I've noticed that on several boats with varying sizes of bilge pumps, which makes it nearly impossible to pump the bilge dry." is not that much of a concern.

My bilge is my adult beverage ice box on three day weekend cruses. It pumps out dry enough Sunday night at the pier.

skip.

[brackish]

Hmm, might try it, (Skips plan), based on the following:

It's reversible, if tests or practical use is unsatisfactory then I go another route with little alteration

I've never actually had a drop of water in my bilge.  I think I have a greater concern that the manual pump will dry rot or the auto pump will become coated with dust and debris and jam if it finally sees some water.  Apparently the lack of a stuffing box to neglect, probably the primary reason for water intrusion when a boat is left unattended, results in a dry bilge.  Now I have had water come in when pressure washing around the hatch, so I suppose a hard wind driven rain could, however, still not enough to actually make it to the bilge.  The use of that great space as an ice chest for adult beverages certainly has merit to periodically wet things down and clean it out, however, I must not be as agile a Skip, don't think I'd be wanting to climb in there.

in the event I hit something hard enough to hole the hull, the electric will be the one operating, while I'm trying to put in a temp patch on the hole.  If i have crew, then both will be operating, and if one plus two actually does equal three, I'll still be getting the maximum water out.

Skip's analysis of the potential for a following sea to come back through the outlet to the electric pump was something I hadn't thought about, but seems like that would be the case regardless, particularly since I was anticipating another transom mounted outlet.

Thought about the sink as a common outlet, however, on my sitting headroom boat, the bottom of the sink is low enough that the sink outlet is very low on the hull. Consequently I have a shutoff valve mounted at the outlet, that is normally closed.  Another thing to remember.  Would probably have merit on a larger boat with more elevation for the sink.

[crazycarl]

Our Starwind's bilge pump discharge outlet was about a foot above the waterline on the transom.  I had been moving with a following sea for 9 hours and when I dropped anchor.  I had a filled bilge and 3" of seawater on the cabin sole.  After swimming around under the boat looking for a hole, I climbed back up the stern ladder and realized how the water came in.  No scupper valve on the discharge outlet.  I hadn't installed the automatic switch on the 2000gph pump.  I learned my lesson after 2 1/2 hours of pealling wet labels off of cans of food and writing on them with a marker.


I like Skip's idea of using the "T".  Think I'll give it a try.

                            Carl

[skip1930]

Brackish says, "I think I have a greater concern that the manual pump will dry rot or the auto pump will become coated with dust and debris and jam if it finally sees some water."

I had forgotten to mention that the 'debris' concern clogging up the works either manual or electric is a real concern. I de~painted the area so any flakes of paint won't enter any pump mechanism. The second reason to de~paint is for the epoxy to stick and hold in place my aluminum angle that the electric pump is anchored on. Now the only thing I worry about is beer bottle paper labels floating off in the deteriorating ice pile. I do pick those out.

The manual pump being a diaphragm configuration will pump mud providing you have enough arm and is the perfect choice for it's intended purpose.
The electric with a spinning centrifugal impeller must remain clean to flow. This electric pump is kind of like your mom's coat. You put on a coat when your mom gets cold. It just make her feel better. It really doesn't do much...but you feel you have to have it. LOL.

Every season while still on the trailer, I pour in about 10 gallons of water in the bilge to test the manual pump and to finish off the test with the electric to make sure that thing works. It works well enough to sop up what's left with a beach towel. You can buy rebuild kits for the manual pump from West Marine.

By the way. The handle for the pump is snap clamped directly under the Port side settee hatch and any guests on board go through a little dissertation on it's use. Plus on the bottom side of the Starboard settee hatch are the rules of navigation, [red right returning] and radio call procedures [Pan-Pan or SOS, number of soles on board, vessel description, approximate Lat & Lon, nature of distress, ect.] just in case I vapor lock or fall overboard and watch the boat sail away. My passengers get back.

Side bar: Back in the late 1970's I got involved in a little job where some low level radioactive mud from a Kerr-McGee operation was pumped into tankers for disposal using a couple of Wilden Air Operated Double Action diaphragm pumps. The pumps and hoses and all ancillary equipment went with the last load for disposal.

I don't know if it's true but I heard that every day 4 miles of railway is laid in the fly over country of Colorado and four miles of low level radioactive waste is stored in rail cars. All the waste is hospital or medical waste from everywhere.

skip.

[brackish]

Well I did this, the "Skip" plan and the driveway test indicates it is a success.  Sea trials to follow.  Slight variation, I oriented the tee with the small inlet up and put a loop in my auto bilge pump discharge line to the bottom of the bridge deck then back down to the tee.  Seems I shouldn't have any following sea problems with the flapper in place and that high loop in the line.

had difficulty finding a tee with OD's that would accept an 1-1/2" ID manual discharge, and an 1-1/8" auto bilge pump line.  A $1.25, 1" x  1/2" reducing socket PVC tee works just fine if you turn down the large end OD's from 1.630" to 1.5", still plenty of wall thickness left.   The small inlet works fine doing nothing.

still need to get the Admiral to pump the manual so i can stick my head down there to make sure I'm not getting any blow back into the auto line at the tee.  Don't see how that could be possible with the high loop and enough discharge area so no back pressure can build.

[skip1930]

I used reducing tees and bushings for the plumbing. It will work just fine, a vacuum break created by a high tee is a good idea.

skip.