Sudden crack in C41 Perspex deck window

[Tarrant]

Looking for help. Yesterday discovered vertical crack in port side deck window on lightly sailed C41 9 years old. No obvious idea as to reason. Bavaria agent says need to change to glass now as Perspex faded out by Bavaria. That means changing 4 windows!! They have estimated at about £900 plus vat each plus fitting !!!! Talking £7000 plus!!! Do Bavaria have replacement Perspex windows or a template to cut too?

[Yngmar]

Checked SVB? They're an official Bavaria parts dealer.

DIY it'll cost less than 10% of that quote, even if you buy a router to flush cut from the old and an oscillating tool to scrape out the old gunk. Or send it off to have a company remake them and just install them yourself.

[Impavidus]

Looking for help. Yesterday discovered vertical crack in port side deck window on lightly sailed C41 9 years old. No obvious idea as to reason. Bavaria agent says need to change to glass now as Perspex faded out by Bavaria. That means changing 4 windows!! They have estimated at about £900 plus vat each plus fitting !!!! Talking £7000 plus!!! Do Bavaria have replacement Perspex windows or a template to cut too?

This is a known problem with the Farr design hulls. I have posted a previous article with regard to leaking at the joint between the two sections of window and the adhesion of the 3 way joint.
The exact same issue has just happened to our 2015 Bavaria 37. The starboard side window has split at the forward section. The port windows are showing the same level of stress cracking. I used to work in the window and facade industry so it is a subject I know a bit about. The issue is due to the rate of thermal expansion between the deck molding in white and the cast acrylic sheet that is dark tinted.

BAVARIA ARE AWARE OF THIS LATENT DEFECT.

The deck molding and the acrylic expand at different rates in strong sunlight. The rate of expansion is very pronounced and this causes stress fractures in the acrylic and leaks at the joint between the saloon window and the aft cabin / heads shower, depending on your model. The adhesive (mastic) used is a high modulus polysulphide mastic / bonding compound that has an in use lifespan of around 5 years. 
Even the very best glazing / bonding mastics from Arbosil, Sika or Dow Corning only have a lifespan of around 8-10 years. Commercially Dow will not warranty their products above 10 years and that is if production samples and batch tests are carried out during the glazing process.

So where does that leave us? 

We are going to replace the saloon / aft cabin / heads window set on both Port and Starboard. We are going to ask a company in the UK to produce the new cast acrylic windows from templates we will make in a few weeks time. The projected costs are around £300-£400 for all the window without the fritting.
We/I used this company when we were in business they are very professional. When and as we do this project we will cover it on our YouTube channel.

Footnote; The rate of thermal linear expansion between monolithic glass fibre castings and mouldings is very different from the rate of; Toughened glass (not really suitable in this application) standard float glass (a dangerous choice) The best choice is heat soak tested toughened laminated glass (4-2-4) 10mm which would be the best choice but it will debond after time because of the thermal issues.
We will keep you all updated as we look at this issue, Meanwhile,  Bavaria know the issue and will keep kicking the can down the road.

If enough people respond we would be happy to take this on with Bavaria, make a video on the issue as there are a lot o the Farr designed hulls that are having the same issue and will need remedial works.
Sail Safe Guys, Ant & Cid   
Email us @ impavidussailing@gmail.com for a faster response...