Beneteau 40.7 water in headlining troughs

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ernestltd

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Hi

After lots of rain I am finding a lot of water (at least a cup full) in troughs Port and Starboard in the headlining plastic moulding in the aft cabins? Is this leaking deck hardware or condensation. Every time I open a headlining panel I cannot find any issues. I can access the deck/hull joint and there is no water leaking there.

How much condensation should I expect? My dehumidifier 5Litre tank fills up after a few days.

Any other 40.7 owners seeing this?

Thanks
Jeff
 
I can't quite picture where you refer to.

When I did a mile-builder in a First 40.7, the shelves in the forecabin (marked in red below) filled with an inch or so water, and waves formed in them with the motion of the boat, splashing down onto the forecabin mattress.

CPGMeA6.jpg

The skipper believed the water ingress to be where the hull-deck joint was formed above the shelves. The deck has been laid onto the hull and secured with long screws. If you get your head underneath the deck joint (marked in blue below) you can just see the tips of the screws nearly poking through the fibreglass.

The screws which hold the deck to hull go right through and then, if you look carefully, you can see that a short length of fibreglass tape has been soaked in resin and stuck over the bottom of each screw. Thus water is able to enter the GRP around the hull-deck jointing screws but, for the first few years of the boat's life, is unable to exit. Once the boat is out of warranty, no doubt exacerbated if the water freezes in the winter, these start to leak.

The skipper I sailed with told me he'd want to spend weeks rebedding all the deck hardware, should he be asked to sail this boat again for an extended period.

SE9JEaA.jpg
 
I had lots of rain coming through the through deck fittings of my side stays, as in liters after heavy rain.
Now these had particularly large holes that were impossible to seal which is not relevant to this story.

But the main thing is that rain can stick to vertical stuff and turn in to a continuous stream rather then a drop every now and then.

And streams can also occur horizontally (maybe starting vertically).
So, have a look at how water may stream rather than trickle and see where that water may pass some holes, in this case on both sides of the boat.

And it may always start where you do not expect it, like going down through holes at the mast support and then travel somewhere else.
 
Blimey, some excellent posts.

I had a GRP Folkboat once, with a 4ft deep bilge, it was bone dry, in fact it was not even fitted with a bilge pump when I bought it. No condensation there.
So all I can add is, whenever I have tried to kid myself dampness is condensation, in the end it always seems to be a leak. : -(
.
 
It’s likely to come down to some patient ‘leak detective’ work...

Remove all headlining/trim panels that you can. Take them home, even, to store them safety while you live without for a while and monitor the area.

Also pay attention up on deck. Anything not look right? Any after-market additions (cable glands, deck fittings) that might be a culprit?

Bear in mind that water can move a long way in often surprising directions and collect far from the source, as suggested above.

Consider masking-taping some blue roll or kitchen paper in likely routes and see whether they show up the passage water is taking - to try and trace it back to source.

On an older boat, re-bedding all deck hardware is often the answer. But on a newer boat, it’s likely to be just one culprit. The tiniest leak can cause water to pool inside.

Yes, it could always be the hull-deck join, but it’s not as likely as a rogue fitting/seal.

Good luck!
 
dankilb said:
It’s likely to come down to some patient ‘leak detective’ work...

Remove all headlining/trim panels that you can. Take them home, even, to store them safety while you live without for a while and monitor the area.

Also pay attention up on deck. Anything not look right? Any after-market additions (cable glands, deck fittings) that might be a culprit?

Bear in mind that water can move a long way in often surprising directions and collect far from the source, as suggested above.

Consider masking-taping some blue roll or kitchen paper in likely routes and see whether they show up the passage water is taking - to try and trace it back to source.

On an older boat, re-bedding all deck hardware is often the answer. But on a newer boat, it’s likely to be just one culprit. The tiniest leak can cause water to pool inside.

Yes, it could always be the hull-deck join, but it’s not as likely as a rogue fitting/seal.

Good luck!
Click to expand...
Yes, blue hand towels/wiping paper is an excellent medium for showing up trickles of water. It's often found in public toilets and service station forecourts.
 
Just one thing in @ernestltd's original question that I see none of us have commented on - it's definitely not condensation.

Typically condensation just makes the underside of your mattress a bit wet

A bad case of condensation (living aboard during a wet October) and there will be drops of water on the windows, ceiling and inside the coachroof - a dehumidifier will reduce this to normal within days.
 
On my Benny, there was a small water leak from the stanchions just aft of the stays. Easy to get a socket up there and remove , rebedded with butyl and not a drop since. It is a common leak area as crew are always pulling themselves on board.
Cheers
 
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