Lewmar fixed portlight leaking

[umu]

On our B37 2006 I noticed a slight leak on the fixed elliptical portlights made by Lewmar (mounted below deck, about 50cm above waterline).
This only happens when going hard to windward for an some time, was not able to reproduce the leak with a water hose.

Anyone got that before and has hints about possible root cause?

[Symphony]

First you need to determine if the leak is between the frame and the hull or the frame and the glass. No secret about the cause of leaks. Failure of the seal between the faces. Solution is to remove, dismantle and reseal as necessary. Not always easy as suspect that the portlight is glued to the hull.

[umu]

Thanks Symphony - that's what I tried to figure out with hosing down the portlight. However no leak whatsoever just with water from the hose.

And when sailing hard to windward I can see after a while that it gets wet below the portlight, however no chance to see where exactly it comes from, it seems not to be between the glass and the seal (seal seems dry on the inside), but could be between the seal and the frame or the bedding of the frame or the point where the frame halves meet.

That's why I asked if someone has had a similar pattern and figured what the cause was.

[dawntreader]

Are you sure it's the side portlight?  I thought mine was leaking too but after detailed investigations found water entry from on top, along the ceiling ridge and down past the portlight. I fixed the leak (roof portlight seal) and the side portlight hasn't leaked since  This may explain why no water entry despite hosing down 

[Clivert]

We had the same problem on our 2001 '34 fitted with Rutgerson opening portlights.
The are bedded on foam seals.
On removing the portlight I found the the seal was not bedded properly, so I simply fitted a new foam seal and problem solved

[Stockie]

I have the same model and year, and both my hull windows leaked.  So I undid the screws, after soaking with WD40 for a week.  Tip, take all the screws out, bar one at one end, swivel down the backing plate, reinsert the opposite screw, without going through the back plate, and tie a line on and anchor it to the side stay strut. This will give you a back stop if it pops out, into the drink!
Mine tapped out easily enough, and I was underwhelmed by the amount and placement of the foam sealant, pretty ordinary I thought!
I cleaned both surfaces and applied Sika marine sealant, and reseated.  Just sanded and re varnished the wood panel that was starting to look scungy, it came up nice with satin clear.
Give it a try, glad these Bavaria only have one window!
Richard