Salt crystals under bed

[ArthurWood]

A few years ago after returning from a 6-week cruise to the Bahamas, I found several gallons of fresh water in the storage area under the mid cabin bed in our Sea Ray. I pumped it out and dried the area and kept an eye on it for several weeks after. There was no recurrence during those several weeks, but a few months later I looked and, behold, water. I still have no idea where it came from. Fresh water pipes and the toilet exit pipe run through there but there was no indication of a leak.
Last weekend, and now at least two years since water was present, I opend the compartment to pull out some stored cushions which I had been careful to protect in a plastic bag in case of more water ingress and this time found a thick layer of salt crystals completely covering the bottom of the storage area. The deposit is very salty but is dry. This is really puzzling me as you can imagine. Could it be dried urine deposit, although there is no smell whatsoever or could there be a hull leak, but if so, why is it intermittent? If there were a leak in the toilet system, the vacuum pump would run constantly and it doesn't. If there were a hull leak, surely it would not be intermittent. Any thoughts (constructive) would be welcome.

 

[Greenwichman]

I have had a similar problem in my Beneteau 285, with very intermittent instances of water ingress, sometimes saline, sometimes not.

After several years of cursing and brooding, it occurred to me that rough weather was a common factor.

Carefully analysing the possibilities, I concluded that the only way that water could find its way in - all other obvious routes having been sealed and double-checked - was via the (VERY small) conduit for the electrical supply to the bow navigation lights, situated in the chain locker.

Later, head down in the locker, with a viewing mirror and a bright light, I placed waterproof sealant in the mouth of the cable conduit ..... and the problem went away.

The moral of the story is - it will be something less than obvious, very small and (when you finally solve it) it will release in you a "Eureka moment" that will make the hassle seem worthwhile.

Good luck!

/forums/images/graemlins/smile.gif

 

[alienzdive]

I would imagine the salt crystals are left over after the water got in and was left unnoticed, then over time evaporated, leaving the salt water behind.

Sorry still does not tell you the cause of the problem though.

 

[simonfraser]

i found some small holes behind the rubbing strake after a lot of searching . . . .

 

[Amphitrite]

The fresh water may have been there because it leaked out of the vents of the freshwater tanks when the boat had a great heel....

 

[ArthurWood]

Thanks for your responses. The place in question is about 30ft from the bow and I don't see how salt water could have got that far back from the anchor locker, which actually drains overboard at the bow.
The fresh water tank is also in the bow, a long way from the storage compartment.
The rubbing strake may be a place to look. My boat doesn't heel like a sail boat to the extent that the rubbing strake is submerged, but water does come up over the strake when diving off waves!
Re crystals: yes, I assume salt water has evaporated.

 

[cliffordpope]

It must be very dry for salt to crystalise out of sea water. Normally salt attracts water and goes wet and mushy (hence the additives in table salt).
Is it actually Sodium Chloride salt, or some chemical or cleaner that has been spilt?

 

[ArthurWood]

Clifford - I tasted the crystals and they are very salty - and there are lot of them! I suppose they are not absolutely dry, but very slightly mushy. The boat has aircon constantly and a dehumidifier running intermittently.
The compartment is completely - on the face of it - sealed and lined with a hard grey paint. Nothing apart from fill-in cushions and their supporting boards has ever been stored in it since the boat was new. Several pipes run through it, but there is sealant where they pass through the walls of the area.
I'm mystified to say the least!

 

[Swagman]

If the crystals are rather large then we have the same issues annually. I believe ours is salt water coming in - mostly via mast - and initially settling in out of the way stringers etc until finally it ends up as 4mm deep bilge water. We park up in a hot climate - and four weeks unused see's it reduced to those large crystals - which we hoover out.
Cheers
JOHN

 

[ArthurWood]

Your crystals seem to be like mine - some are about 1/4" cubes. But my boat doesn't have a mast!! I shall investigate further. Thanks.

 

[BrendanS]

Arthur, can you dust the whole compartment with talc powder? Then if you get another leak, the source should be more easily apparent

 

[ArthurWood]

I can do that, Brendan, after I've cleaned out the crystals. Thanks

 

[BrendanS]

get a puffer bottle and dust everywhere, including upside down, and on the pipes

Any leaks from that point on should be apparent, even if they happen months or years later. You can trace the leak from the wake in the powder even if it happens intermittently

 

[PuffTheMagicDragon]

[ QUOTE ]
The boat has aircon constantly

[/ QUOTE ]

Maybe the airconditioner uses seawater for cooling? if it does, then perhaps there could be a slight leak somewhere along the discharge line.

 

[ArthurWood]

Yes they do use seawater, but both outlets are on the opposite
side from the problem area. But come to think of it, the inlet is on the problem side and I think the hose runs through that storage area. I'll take a look at it again. Thanks.

 

[ArthurWood]

I think I might be getting somewhere: I cleaned out the mushy salt yesterday and have put some fresh water in the compartment to dissolve the few remaining particles. I'll suck the water out today. The aircon intake hose does indeed run along the bottom of the compartment, to one side. It's one of those translucent plastic hoses with what appears to be an embedded reinforcing nylon mesh. The whole think is wrapped in a protective plastic sheath like the ones used for keeping electrical wiring together. I can't thing how the hose could get punctured, but once I've dried the area out I'll have a closer look.
There is no obvious ingress of water while the aircon is running so I can only surmise that when the boat was at the yard for several weeks in the water with no aircon, there was pressure in the line, enough to force water into the boat. That's my theory anyway.