Aft Sump Flooding!

[Michael Moradzadeh]

In this year's "Spinnaker cup" race, the wind was string and on the nose, so it turned out to be a bumpy upwind slog of about 90 miles.

Our J40 made it about 10 miles and retired.

Our excuse? A lot of water in the cabin.

We were heeled well to port, burying the rail, and slamming a lot. Crew noticed a couple inches of water standing in the port corners of the cabin.  I bailed out out, but it refilled quite quickly.  Time to quit!

My theory is that the water was coming in through the shower sump line.  Either siphoning or the entire assembly was below the waterline enough that the water could just flow in. 

 I will head back to boat this morning to freshwater rinse everything, turn on a dehumidifier, and eyeball the situation to see if my hypothesis holds.... water.

Michael

O2, 190 J40

[Tom Keffer]

Don't know about a J/40, but my J/42 will flood through the sink in the aft head when on a hard starboard tack. 

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[John Hope]

Same on a J-40. We close the thru-hulls in the forward and aft heads when we’re sail hard on the wind. 

John

Misty Rose

J-40 #80

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[Chris Leo]

I had this problem on one of my first cruises when I bought j/40 Cowbuoy in 2018. On a port tack, the cabin began filling with water from the aft. It turns out the starboard cockpit drain was cracked in its final turn towards the aft thru-hull. So water was freely flowing into the boat on that tack. 

I put a wooden plug in it and sailed on for the next 6 years like that, until I finally replaced it all in 2024. It’s just impossible to get back there, when I removed the aft water tank it finally created enough room to at least exist back there and get the job done.

On Sun, May 24, 2026 at 12:48 PM Tom Keffer <tke...@gmail.com> wrote:

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[Michael Moradzadeh]

That's interesting....  I believe my surveyor noted something like that and I had the boatyard deal with it.... I think.

Dang, now I gotta go check that too.

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[Jim Bordeaux]

When heeled hard to port, J40 can get flooding via the sink in the forward head.

Sent from my iPhone

On May 24, 2026, at 1:43 PM, Michael Moradzadeh <m...@yachtpc.com> wrote:



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[Michael Moradzadeh]

aha.  did not look in the forward head.

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[Al Goethe]

Flooding through the forward sink is a pretty common problem I think. J/44 has it. I’m sure J/46 would have it, too, except Hamburg II (#31) has a check valve on the sink drain that prevents that. 

When heeling hard in heavy air it’s always better to have these seacocks closed. 

Al Goethe

On May 24, 2026, at 11:48, Tom Keffer <tke...@gmail.com> wrote:



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[York.richardw]

MM-

On at least one 42, there was frequent siphoning of water back through the electric bilge pump hoses.   Although there was a loop, it was no where near high enough, and had no anti-siphon valve.

Worth a peek.

… Dick

On May 24, 2026, at 15:28, Al Goethe <ankg...@gmail.com> wrote:

Flooding through the forward sink is a pretty common problem I think. J/44 has it. I’m sure J/46 would have it, too, except Hamburg II (#31) has a check valve on the sink drain that prevents that. 

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[Fred Hawes]

Gentlemen,

I want to thank the person that decided this was an appropriate topic for larger J boats. Twice, Anona (J-46 #15/35) has had water coming up thru the sole in the port side of the galley, while ocean racing in 4 foot chop. I have, until now, not figured it out, although I have replaced the aft 5 sole pieces in the main saloon, and the electric bilge pump and associated trigger switch. It sounds like the thru-hull to the aft sink might be the problem on a hard starboard beat. This has never happened in the bay.

Thanks guys,

Fred Hawes

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[David Jade]

We have had sea water come up through the aft sink drain once or twice and overflow on a rough passage. It seems the one-way valve in the drain lines occasionally acts just like one of those shaker-siphons. Our solution is to just close the seacock when it happens.

                                                                                                           

Hmm, now you got me thinking. Has anyone ever seen this bilge siphoning on a J/46?

 

We had an instance of a mysterious amount of salt water appearing in the bilge after a 4-day offshore passage and we haven’t been able to locate the source. It is not the usual water down the mast into the shower path as our mast boot does not leak even a drop nor does anything but rain water ever get inside the mast.

 

Siphoning from the bilge is about the only theory I’ve been able to come up with since we can find no evidence of a path that water took to get to the bilge. We have an anti-sipon valve on the loop in the forward closet but one thought now is that maybe it got fouled and allowed siphoning with a good amount of rolling and heel.

 

David             _/)

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[Michael Moradzadeh]

Yeah the lack of good anti-siphon is my prime suspect.

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[Todd Stevens]

Well, one more possibility that I mentioned in another thread - 25 year old bilge-pump hose recently removed from my boat was brittle and easily cracked.  Considering that the through-hull is almost at the water line on the port side, any cracks toward that end could let water in when heeled.  Worth checking and/or replacing before that happens.  

My vented loop is found near centerline up in the top of the galley cabinet. Seems high enough for most occasions? 

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[Dick York]

Todd ....  good point on the brittle hoses.  

I actually had to do a pan-pan from ARAGORN one night, at 2300.  Sailing very fast and water coming in the boat.  

The drain from the propane locker exits far aft, just above the waterline.  Of course it was below the waterline at 8 knots.  

The 22-year old drain hose was hit by an errant box not properly tied down, and the wear cracked the ancient hose.    Nice water intake in an almost invisible place.

Two aboard; I was able to divert to Pilot's Point easily. The crash pump worked its magic, and we (of course) took on no new water once tied to a dock.  

It took me two days of unpacking a loaded boat to find the bad hose.

I need to find all the old hoses and have them replaced on a regular basis.  I used to do that on the engine with a great mechanic.  But now we should be looking at all of them.

BTW, does anyone know the lifespan of a Propane gas hose? Anyone have an ABYC spec on this??

Thank You ... Dick York

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