Leaky Beneteau 393....

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SailingGirl

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We are dealing with a mystery leak on our Beneteau 393. The bilge seems to be filling up. The fitrst thing folks are telling us to check is the prop. We have checked the engine and compartment and it is bone dry so it cant be the prop. All through hulls are tightly closed and dry, we have yet to fill the water tanks. There was condesation in the fwd tank area but not enough to fill up. The water in the bilge is clean so where else can it be coming from. Any and all suggestions welcome. Thanks, SailingGirl.
 
Sounds like the forward tank. Condensation is always my excuse to the wife when we get fresh water in the bilge, but it's normally come from the deck.

On deck, toe rail screws are a bugger for it, also cleats get put under a lot of strain in mooring. Aftermarket deck hardware that might not have been well installed.
I had a U bolt for stowing a moveable forestay for instance. The bolts hadn't been tightened and no sealant at all.

Water heater can leak as well, there will be a pressure relief valve that probably empties into the bilge.
 
I presume it's a keel-stepped mast? Check the mast gaiter for leaks, plus don't underestimate the amount of rain water that can find its way down through the mast (halyard entries, wire entries etc etc) if you're inspecting after a lengthy period.
 
We had wet bilges when we acquired the boat but not on the scale you describe. Two causes; water heater without an expansion tank leaked a bit through the PRV every time it heated up and the water pump aluminium body was fractured slightly on the high pressure side and constantly leaked. Both fairly easily dealt with!
 
I have recently spent ages tracing fresh water leaks on a fairly similar modernish boat.

In the end found and fixed:-

Calorifier PRV - my first check, now on 3rd PRV in 18 years, and I do click the valve round every so often as you are supposed to do every month according to the instructions.

Calorifier hot water outlet - tiny leak that when water was hot evaporates and you don't see it, but get off the boat and leave system prerssurised and it slowly drips out.

Leak in pipe joints to T-piece in hot water system for expansion "hot-pot" tank

Leak in body of freshwater pressure pump

Leak in piping joint to transom shower fitting.

All these were the sort of leak that really wasn't very visible "in use" - but leave the boat for a few days with a pressurised water system with a 5 litre expansion tank and most of 5 litres would end up in the bilge.

As Hoolie has said - check the PRV first. I have long since disconnected it's pipe to the bilge and routed it into a plastic 2 litre bottle so you can see if it is leaking. If it stll leaks after changing it you need a bigger expansion tank.
 
jwilson said:
.. leave the boat for a few days with a pressurised water system with a 5 litre expansion tank and most of 5 litres would end up in the bilge.
Click to expand...
One of my shut down checks is to turn the pump off and depressurise the system. I use the last of the fresh water to flush/fill the toilet bowl.
 
Here are pics of the drain to the bilge where it is coming from. If you are familiar with Beneteaus 393 it is on the starboard side of the couch under the table. All Other areas are dry that lead to this drain.
 

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Inevitably any water finds its way down to the lowest point in the bilge. That does not help finding the source. As it is fresh water it is either coming from the freshwater pipework as already suggested or from the outside from leaking fittings or windows/hatches. No alternative to checking everything possible, starting with the freshwater system as this is both the easiest and most likely.
 
So happy to report that I found the leak. It was the filter cup for the AC/ Heating intake. FFS. I was kneeling on the only floor board that I didn’t lift up in my search. Cleaned the filter cup and checked the seal. The cup had shaken itself loose.

Thank you to all who took interest in this posting. Definitely a learning curve.

Happy Sailing!
 
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