Chronic leak in the Beneteau Oceanis 473 deck

[MauHof]

I'm a very happy owner of a Beneteau Oceanis 473. I bought this sailboat four years ago and crossed the Caribbean Sea a few times with her. It is a very comfortable boat and well built. But I'm having a recurring problem with the portlight that is fitted over the deck (see the picture below). It's kind of windshield. It's very big. It seems that it has three parts, but it is only one piece 2.5 meters wide and 0.5 meters long. It is glued externally over the deck. The only thing that keeps it in place is glue. And that's the problem. It goes off at the ends and leaks both rain water water and sea water while saling. The regluing has been done o couple of times, but it gets loose again. I am affraid that some day it simply pops out of the deck.

Does any owner of Beneteau Oceanis 473 had this problem?

Some have suggested to close this lightport with fiberglass, but I find that very radical.

I thought of screwing it on deck, but I fear it may break.

Does someone have any suggestion? An special glue? Some tipe of fittings?

Thank you for any advice.

Mauricio Hofmam

[rognvald]

Mauhof,
It appears that there is an "applied force" from port and starboard created when the vessel is underway. It is the most likely conclusion based upon your statement. The only way to remedy the problem is to negate the force with additional support under the deck-- preventing movement, or to remove the panel and re-glass the opening. My opinion is that it is a design flaw inherent to that particular model and others like it. Why not go to a Beneteau's Forum or contact the company direct? Good luck and good sailing.

[Dulcesuenos]

Not sure what glue has been used in the past, but my recommendation is to Remove the windows, clean and sand where they bed, clean with some denatured alcohol, tape and sand / clean the glass where the sealant needs to go. and use DOW corning 795. We used this on the windows for our Leopard 38, its very durable and strong, but surface prep is important. They use this stuff to install windows in sky scrapers.

DOW CORNING® 795 SILICONE BUILDING SEALANT

[donradcliffe]

The problem is not that the opening is flexing, it is the differential expansion of the lens and the opening when the sun heats things up. The sealing joint has to accommodate that lateral movement, or the seal will break loose. Larger windows mean more expansion and more leaks. Good workmanship and seal design is important--the thinner the layer of sealant is the more likely it will break loose. If you look at the rim of a aluminum hatch, you can usually find that it is made so that there is a ring of sealant 1-2mm in thickness to let the lens expand without shearing the sealant. If the use of a really good sealant like Dow 795 does not solve the problem, maybe you can rout out a ring in the opening material to provide a thicker seal.

[7623]

I agree with the last poster, the problem is most likely temperature expansion. The window needs to sit on a thick layer of sealant / glue.

That size window I would go for about 10mm. I have done this successfully on a window of 2.7m length. Here in Australia I used a Fixseal product but dow corning should work well too.
I went through about 8 cartridges...

Sent from my GT-I9506 using Cruisers Sailing Forum mobile app

[7623]

If you could cut the window into 3 and put expansion joints between each piece, that would be even better!

Sent from my GT-I9506 using Cruisers Sailing Forum mobile app

[bsurvey]

3m 5200 should solve your problem. it is adhesive not caulk put a tooth on the glass and one on the opening


this is a bad design flaw and may have more to do with the mast and compression loading

[Cheechako]

I agree... that's a long piece of plastic.. and it is likely expanding and contracting a lot. I would imagine there are also stresses on it from the boat twisting and bending also.
If it were mine, I would probably cut it into 3 pieces and bolt it in place around the perimeter an use one of the sealants mentioned above.(may require new plastic)

[hamburking]

I had a 1982 C&C27 with side windows attached with glue as you describe. The previous owner had already stripped and reglued the windows, and included the complex jig he had built to apply pressure while the glue cured.

My jumping around on deck quicly caused the ends of the windows to pop out. At first I used SIKAFLEX to stop the leaks. Later, I put pails below every time it rained.

In researching the problem and speaking to other owners (who all had the same issue), I found there were two common solutions. The first was to drill through and bolt to the inside. The risk of this is to crack the window from stress concentrations. The prefered solution was to have a window frame built of bent channel aluminum with a rubber gasket all the way round, like most older boats. This solution cost more, but was effective, and looked good if done right.

My solution was to sell the boat.

[Duchie]

Some of the answers are correct : 1, take off the window and clean off and out all the old ahesives ,:2 , use Dow Corning as mentioned before ( I stuck all my windows on my 48ft Crowther cat with this product 3 years ago ) but you need a thickness of 5mm thick by 50mm wide , (I used soft rubber spacers to maintain the 5mm thickness ,) this will allow for expantion and contraction , then , once the window has been placed , allow at least three days for it to cure, check Dow
Cornigs specs , You can drill over sized holes for screws and a washer at the exstreme end of the window to hold them down , ( and leave them in place ) , if the material is not to old and perhaps brittle , in that case you need a new window anyway . Cutting the window in sections with 5mm gap between them ,will reduce the overall expantion , but then you have to hold down 6 ends that want to lift up while curring . I hope this is of some use to you .

[MarkJ]

My Beneteau has a similar window. Fortunately it doesn't leak. I have always looked at it and thought DON'T TOUCH IT!
But you obviously have to.
As others have said, check B473 forums. There's a B393 Yahoo Group if u can't find a B473 group.

I would get a Beneteau agent/yard/etc to do the job. It must be done by someone who has done the job before successfully and using the exactly correct product (obviously 5200 is not the right one!).
There must be a trick or 10 to the job. Laying a curved 10 foot window on a 24 foot line is sticky sealant perfectly ain't gonna be easy! A pro job, me thinks.

All the best

[MarkSF]

What's needed is not necessarily a Beneteau yard, but someone with experience of bonding windows to fibreglass. The devil is in the details - correct preparation of the surfaces, correct sealant, thickness of sealant, and so on.

[MarkSF]

"apply pressure while the glue cured." There's a problem, right there. You need to space the window off the fibreglass, to get a good thickness of sealant, which will allow for flex. Applying pressure just squeezes it out.

[nigel1]

I have a 2001 build 473, and no issues with leakage in this area.
My first step would be to contact a good Beneteau dealer and ask them if they are aware of this problem, and if the are, what is the recommended fix.
They were very helpful with advise when I had to re-seat the lower bearing on the rudder stock.

[leftbrainstuff]

Originally Posted by MauHof

I'm a very happy owner of a Beneteau Oceanis 473. I bought this sailboat four years ago and crossed the Caribbean Sea a few times with her. It is a very comfortable boat and well built. But I'm having a recurring problem with the portlight that is fitted over the deck (see the picture below). It's kind of windshield. It's very big. It seems that it has three parts, but it is only one piece 2.5 meters wide and 0.5 meters long. It is glued externally over the deck. The only thing that keeps it in place is glue. And that's the problem. It goes off at the ends and leaks both rain water water and sea water while saling. The regluing has been done o couple of times, but it gets loose again. I am affraid that some day it simply pops out of the deck.

Does any owner of Beneteau Oceanis 473 had this problem?

Some have suggested to close this lightport with fiberglass, but I find that very radical.

I thought of screwing it on deck, but I fear it may break.

Does someone have any suggestion? An special glue? Some tipe of fittings?

Thank you for any advice.

Mauricio Hofmam

Bonded surfaces often fail due to loading by peeling. This is an assymetric tensile force normal to bonding typically at an end or change of direction. Elastomers tend to be strong in pure tension and shear and perhaps compression but weak in peeling.

This may be due to a flat panel bonded to a curved surface or a warped surface.

If its just bonded with no support it will need a very stiff base and a flexible panel to seal well. If you have flex in your deck or a very stiff panel this may fail repeatably. Matching the elastomer to the joint is important. For example a less compliant elastomer will carry more compression loading but will fail in peel more readily.

Have you identified the initial failure point? Is it simply an issue of a stiff elastomer? Could a more compliant elastomer solve your problem. What does Beneteau recommend?

On our Liberty 458 all glass and ports are retained by stiff bronze through bolted flanges surrounded by epoxy dams. The hull and deck are also very thick and stiff. The sealant is only loaded in compression.

You might want to investigate options to add a through bolted flange. Careful attention to ensuring epoxy dams as potential leaks is avoided is needed.



Sent from my SM-N900T using Cruisers Sailing Forum mobile app