bilge pump discharge

[Obx]

My main bilge pump hose is connected to a thru-hull that has a 90dg pointing up. When it was installed they did not put a 90dg or sweep on the fitting so the hose could connect without being bent over. I have looked at Lowes/hardware stores and on line but cannot find one for my 1 1/2 thru hull.
Can anyone suggest where or provide a link.
Thanks in advance

 

[HopCar]

If I understand you correctly, I'd guess they want you to run the hose higher than the thru-hull to a vented loop and back down to the thru-hull. This is important if the thru-hull is less than about 18 inches above the waterline.

 

[jwnall]

If I understand you correctly, I'd guess they want you to run the hose higher than the thru-hull to a vented loop and back down to the thru-hull. This is important if the thru-hull is less than about 18 inches above the waterline.

What Parks said.

 

[Al]

Yep!! This past summer while traveling and with additional folks on board, we had bilge water building enough that I had to pump every couple of hours to discharge a couple of gallons. In a 27' boat it doesn't take much to look like a lot when there should not be any.

Could for the life of me, figure out where the water was coming. checked every thruhull and the shaft for leaking. Nothing. While at anchor not a drop and the bilge was dry.

3AM it came to me. A bilge pump installed as a secondary main backup was installed by myself and I assumed that the bilge pump has a built in check valve. Silly me. we found that under power the thru hull was running at or below the water line that rolling was allowing water to backfill.
Ran the hose up to the under floor and back down to the thru hull and bingo!

Al-Ketchikan

 

[sdowney717]

I used pool suction hose for the entire run from pump to outlet.
It conforms easily to a smooth curve. And it is robust, tough hose.
If you examine the inner surface, it has flattened ridges, so smooth wall. It is after all designed to flow water in your pool.

One I used was 1.5 inch diameter. Also had a 1.25 inch diameter hose.
So two Rule pumps, pool hose to upturned outlets set 90* glued into the hull, with hose arcing up then down in a smooth sweep.

I used black polypropylene 90* 1.5 inch street elbows, glued into hull with Loctite S30 and the tube end glued into the expanded end of the street elbow.

If it won't fit your fitting, lightly heat end of hose with a heat gun, it will soften and stretch.

here is basic idea, compare with the 3/4 copper original design. Original design simply a 3/4 elbow passed thru the hull with a large copper washer screwed on outside.
My plastic arrangement is not different in essence than what the OEM did 45 years ago, yet a whole lot bigger capacity.

Wood is 1 inch thick.
Plenty of surface area for the goo to hold.
And sanded flush to hull. nothing to catch-snag.

Other end of hose is clamped to bilge pump outlet with standard clamp.

And this hose sat outside exposed for 10 years, when we had a pool, so it holds up to the environment.

 

[Obx]

Sounds like a fix using the swimming pool hose
Thanks

 

[kapnd]

Not too sure the swimming pool hose would be my first choice for a worry-free discharge hose, as I have had many of them fail in my pool.
Your application puts the hose under pressure, where it is designed as a suction hose.
Flexible PVC hose is readily available, and is pressure rated, and glues up nicely to standard PVC fittings.

 

[FF]

kapnd,,

Just noticed that nice Grey boat.

Taking our 50 Utility ,,CT to Hawaii would be great fun , but the fuel tanks are too small.

 

[kapnd]

Fred,
Well, I often think about just the opposite trip, as cruising here is really quite limited. You can go from island to island, but good anchorages are limited, and "marinas" as known on the continent are almost nonexistent.
Boating here is truly boating in the middle of the ocean, with uninterrupted fetch for thousands of miles in any direction.
Did I fail to say that the weather is mild, and it is incredibly beautiful?
I tend to focus on fishing to keep my interest active.
To me Florida is the cruising Disneyland!

 

[Obx]

Not too sure the swimming pool hose would be my first choice for a worry-free discharge hose, as I have had many of them fail in my pool.
Your application puts the hose under pressure, where it is designed as a suction hose.
Flexible PVC hose is readily available, and is pressure rated, and glues up nicely to standard PVC fittings.

ok on the PVC hose but how do you attach the PVC hose to the metal thru hull

 

[Maerin]

ok on the PVC hose but how do you attach the PVC hose to the metal thru hull

If the thru hull is threaded, you'd connect a barbed fitting adapter to the thru hull, and double clamp the hose to that adapter. Preference of materials from best to least would be bronze, marelon, nylon. No PVC, NEVER brass, and always a connection that's mechanical based- IOW has a clamp, thread, or some means to mechanically secure the connection other than glue.

 

[FF]

"To me Florida is the cruising Disneyland!"

The FL West coast is a delight , the FL East has few anchorages south of Daytona till the Keys and is mostly for the M>M set. (marina to marina)

WE prefer New England with tons close well protected anchorage harbors , with central heat 3 season cruising is a snap.

 

[rwidman]

If I understand you correctly, I'd guess they want you to run the hose higher than the thru-hull to a vented loop and back down to the thru-hull. This is important if the thru-hull is less than about 18 inches above the waterline.

That makes sense but the question would be - Why didn't whoever installed it originally finish the installation?

Is this how the boat came from the factory or was the bilge pump installed by someone else?

 

[Obx]

That makes sense but the question would be - Why didn't whoever installed it originally finish the installation?

Is this how the boat came from the factory or was the bilge pump installed by someone else?

I don't know the answer to that since I'm the 3rd owner.

 

[FF]

The VENTED part of the vented loop reply is the key.

Just an up loop will syphon just fine.

 

[DHeckrotte]

Obx, just buy the vented loop that's sized for your discharge hose. Readily available online, variably expensive. Can certainly be Marelon - 'glass reinforced nylon. Lowes has a better selection of nylon hose fittings sold for lawn sprinkler systems; The Despot has precious little but PVC.

Our FuHwa has no vented loops on the bilge or shower discharge. Hasn't sunk the boat in 35 years, but there's still time...

 

[rwidman]

Ideally, the discharge thruhull is placed where it won't be underwater unless the boat is sinking.

 

[DHeckrotte]

Wes, my preference as well. Both those throughhulls are about 8" above the current waterline, amidships, and apparently do not go under as the boat moves. Putting vented loops on the throughhulls would not be pleasant for me; they're plainly visible in the 18" between the fwd ER bulkhead and the forward end of the stbd fuel tank but they might as well be on the moon, given my size and flexibility.

 

[rwidman]

Wes, my preference as well. Both those throughhulls are about 8" above the current waterline, amidships, and apparently do not go under as the boat moves. Putting vented loops on the throughhulls would not be pleasant for me; they're plainly visible in the 18" between the fwd ER bulkhead and the forward end of the stbd fuel tank but they might as well be on the moon, given my size and flexibility.

I have had my boat nine years now and have noticed that many things that were accessible by me nine years ago are now inaccessible.

My bilge pump discharge hoses go up and then back down but there's no vented loop, just the hose. I figure the designer figured this out before the boat was built and I shouldn't have to change it.

 

[HopCar]

Wes, unless for some reason the discharge stays under water, a loop is fine. If a situation arose where the discharge was continuously underwater, a siphon break (the vent) would be needed. This really isn't much of an issue on power boats but it is on those funny looking boats with sticks and rags all over them. On a power boat the vented loop is just an easy way to get the hose to turn 180 back down to the discharge fitting.

 

[FF]

"Ideally, the discharge thruhull is placed where it won't be underwater unless the boat is sinking."

Large ships will frequently discharge directly thru the bottom as too much energy (GPH) is lost simply lifting water up to no purpose.

Might work on a smaller boat with a remote handle for the valve operation.

 

[HopCar]

"Ideally, the discharge thruhull is placed where it won't be underwater unless the boat is sinking."

Large ships will frequently discharge directly thru the bottom as too much energy (GPH) is lost simply lifting water up to no purpose.

Might work on a smaller boat with a remote handle for the valve operation.

FF I don't think that energy would be a reason to discharge below the waterline. Say the waterline is six feet above the pump. It would take the same amount of pressure / energy to discharge six feet underwater as it does to lift the water to the waterline. Don't forget that water on the outside of the hull is pushing real hard to get into the hull. The pump has to overcome that push before water will leave the hull.

 

[AusCan]

There would be a slight bit of energy saved pumping directly through the hull.
(due to the height difference between the waterline and an above water bilge pump outlet, plus any friction losses)

I'd expect large ships pump directly through the hull to avoid the long discharge pipework required to get above the waterline. The pipe would likely pass through multiple watertight compartments, possibly affecting the integrity.

On our small boats -it's not worth the added risk of having another below water thru hull.