Discoloration around hull porthole windows

Jul 2, 2015
7
Beneteau 423 Hauraki Gulf
Hi there - I own a 423 (2006 vintage). She is lovely boat except for one problem - around the hull portholes over time she develops a nasty grey / black discoloration on the hull. This season I tried to deal with the issue on haul out by wet sanding the gel coat, then cut, then polish then 3 lawyers of wax. All to no avail. 6 weeks later see attached photos.

One possible thought I had is maybe it is the aluminium leaching out and running down the side of the hull? The dis-coloration will wipe off with some scrubbing and is easier with detergent but that removes the wax I painstakingly applied. In either case it still leaves a slight discoloration.

Any suggestion on causes so I can fix the problem? Any solutions on treating the symptoms other than soapy water which destroys my wax?
 

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Oct 19, 2017
7,732
O'Day 19 Littleton, NH
I looked at a couple of for sale ads for the 423, a 2005 showed similar markings but to a lesser degree.
I am incline to think there is a gasket or silicone between the glass and the hull that is breaking down. It looks too dark and too much to be the aluminum. If you see a lot of pitting in the aluminum then maybe you are right. Weather could be a factor, acid rain, smog, but if you don't see similar problems on your neighbors' boats... . Does it need to have rained or does it happen from hose water? Does water even need to be present? Is this boat new to you? Was there a time when you didn't have this problem? Can you see similar marks on the inside of the hull? Is there a sunny side where the boat is always sitting the same way in her slip? Do you get equal markings on all hull ports? Nothing around cabin windows?
Take a camera, set it on macro mode and get close-up pics of the seal where the most leakage is and see if there is corrosion, pitting, cracking, something that could be a breakdown of the silicone or gasket. That is my initial guess.
- Will (Dragonfly)
 

DougM

.
Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
looking at the first photo, there appears to be corrosion or deterioration around the port itself. There is apparently some kind of reaction occurring there with whatever was used as a sealant.
That is far more visible than the leaching that happens with aluminum.
The ultimate solution may require re-installing the ports with a totally different sealing material.
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
My B323 has the aluminum toe rail with holes about every foot. Every so often the dirt accumulates from the deck and will run out the holes and makes the black steaks, but you have the wood toe rail. With the holy rail, the boat can start to look like a zebra. There is a "black streak" remover product, but I don't know how well it works. I get those marks around my port, too.

Use "ON & Off", or "It Works!". It works is my favorite, and is cheaper at Home Depot. They are a bit caustic, so pour or spray a bit on. By the time you reach for the hose, the stains will probably be gone. Works on the brown bow mustache, too- in about 10 seconds!
 
Last edited:
Jul 2, 2015
7
Beneteau 423 Hauraki Gulf
Hi there - thanks for suggestions so far. Yes I will take a closer look at the seal / gasket (though getting a look isn't easy owing to the angles obviously).

Boat was not new to us. It's gradually built up. It doesn't happen over night but over a period of weeks after cleaning it becomes obvious. Not happening to neighbouring boats and we live in NZ away from most smog etc so don't think its environmental. Not sun based either as on a swing mooring.

Marks are not equally distributed and don't appear to be coming from toe rails.

From everything here so far suggests to me it might be the gasket...
 
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Likes: Will Gilmore
Jul 2, 2015
7
Beneteau 423 Hauraki Gulf
Someone has suggested running a bead of silicon around the windows to seal off the gasket so it doesn't produce the leaks. Anyone see any problems?
 

NYSail

.
Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Was at boat today..... just below window. Has to be something with sealant on Windows. Have no leaks with windows but in spring will inspect. Was cold today!
 
Jul 2, 2015
7
Beneteau 423 Hauraki Gulf
Hi there

I think I may have found the solution to the problem. See the thread of the conversation I had with Beneteau technical services.

Dear Sir

Here are the answers of our Spare Parts Department.

Please for any other questions contact a Beneteau dealer

Thanks

Veronique




I assume that:

  1. PMMA is the glass window / porthole (see https://en.wikipedia.org/wiki/Poly(methyl_methacrylate)) è Yes, PMMA is the glass window.
  2. Colle is “glue” è yes, colle is glue.
  3. Normount tape is something like this http://www.totalplastics.com/products/386 è under the blue tape, you have the adhesive normount.



  1. I assume “polyester” is the hull itself? è yes, polyester is the hull itself.

Second, the space between the window and the hull is very small. Do you need to removing the windows /porthole to do this è if the window is not leaking, do not touch it.


If you have to remove the windows is there another solution? I am very reluctant to remove the windows as that is a big job and could create other issues.


Could we run a silicon bead around the window to seal in the glue? Would this work? èYES, this would work. You have to clean the hull, degrease and dry the area where you will do the new seal. This new seal will be of course a silicone glue allowance. You put the silicone glue on the existing PU glue.






De : Paul Adams
Envoyé : jeudi 4 janvier 2018 20:21
À : Véronique MORNET
Objet : RE: technical question for Beneteau


Dear Veronique


Thank you for your email.


I wish to ask a few clarification questions.


I assume that:

  1. PMMA is the glass window / porthole (see https://en.wikipedia.org/wiki/Poly(methyl_methacrylate))
  2. Colle is “glue”
  3. Normount tape is something like this http://www.totalplastics.com/products/386
  4. I assume “polyester” is the hull itself?

Is this correct?


Second, the space between the window and the hull is very small. Do you need to removing the windows /porthole to do this?


If you have to remove the windows is there another solution? I am very reluctant to remove the windows as that is a big job and could create other issues.


Could we run a silicon bead around the window to seal in the glue? Would this work?


Kind Regards,


Paul Adams | Global CEO



From: Véronique MORNET
Sent: Friday, 5 January 2018 5:58 a.m.
To: Paul Adams
Subject: TR: technical question for Beneteau




De : Contact BENETEAUYACHTCLUB
Envoyé : jeudi 4 janvier 2018 17:41

Objet : TR: technical question for Beneteau




Dear Sir,


To what we can see from the pictures, there is no seal on the upper part of the window. In consequence, the black glue is exposed to the UV and the sea sprays.


So you need to put a seal and to polish again the hull.








For any other questions, please contact a BENETEAU dealer

Many thanks

Veronique


De : Paul Adams
Envoyé : lundi 18 décembre 2017 09:21
À : Contact BENETEAUYACHTCLUB
Objet : technical question for Beneteau


Hi there


I own a 423 (2006 vintage). She is lovely boat except for one problem - around the hull portholes over time she develops a nasty grey / black discoloration on the hull. This season I tried to deal with the issue on haul out by wet sanding the gel coat, then cut, then polish then 3 lawyers of wax. All to no avail. 6 weeks later see attached photos.

One possible thought I had is maybe it is the aluminium leaching out and running down the side of the hull? The dis-coloration will wipe off with some scrubbing and is easier with detergent but that removes the wax I painstakingly applied. In either case it still leaves a slight discoloration.

Any suggestion on causes so I can fix the problem? Any solutions on treating the symptoms other than soapy water which destroys my wax?



By the way can I suggest you have a better mechanism for resolving these technical issues than your dealer network? A boat is a huge investment and to have technical problems pushed back to the local dealer who may not have any idea about a problem that faces many different people or occurred on a boat that is older or pre-dates them is very frustrating.


I would very much appreciate a response to this problem as it is marring an otherwise lovely purchase.


Kind Regards,


Paul Adams | Global CEO

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