Window replacement

[Mike_Rose]

We have had our boat for almost 5 years now. When we bought it, there were some issues. One, that I didn’t recognise as a major issue was a crack in the starboard front window. It was a little strange, as it was the inside pain that was cracked. We purchased the boat in Panama in the middle of COVID. There was simply no chance of replacing the window in Panama, so we put a couple of layers of fiberglass over the window to make it structurally strong enough for ocean cruising. On closer examination, the reason the inside pain cracked was because the bottom corner of the front and side windows actually are touching. A bead of silicone was over this fault. It has actually compromised both the front and side windows. I bought the boat knowing the fault, but was still disappointed.

Well, after almost 5 years, it’s time to fix the windows. You can’t actually see there is an issue from the outside as we usually keep the window shades on.

We contact the factory, and unfortunately there has a change to the shape of the windows, and the factory that made the windows is out of business. The new factory uses 8mm glass. We have 6mm.

We are currently in Fiji, so have looked at NZ and Australia for glass options. NZ can supply the glass for 33k NZ. Fitting is extra. And it’s 10mm laminated.
A lot of the cost is scanning the windows and making a mould.

Another option is plexi glass or acrylic. These options are starting to look attractive. They can pull a mould off the existing windows, and the mould doesn’t have to stand the same temperature as a mould for glass, so is many times less expensive.

So, to replace all the windows in glass, we increase the weight of the boat by a lot, and it’s about 70k

To use plexiglass or acrylic, it’s about 4k

Glass lets much more heat through.
Plastic scratches.
Glass can crack, but it’s clearer.
Plastic is actually stronger.

Has anyone replaced a window?

Would you consider plastic?

I’ll include a photo of a boat with plastic windows…

[Mike_Rose]

[Tourterelles]

Hi Mike,

Long night passage here so I thought I would contribute. Whilst I have no direct experience of replacing the windows, a problem shared is a good thing - so these are my thoughts.

On my previous boat (Allures 45) we had plastic windows. The only damage we got was from flogging sheets which would leave pretty impact marks. These polished out (so I assume the windows were acrylic).

On the glass vs plastic - in the circumstances, I would definitely go with plastic - but not all plastics are made equal, you will no doubt be choosing between acrylic and polycarbonate.

As you say, neither are as scratch resistant as glass, but both offer better impact resistance with polycarbonate having excellent impact resistance but less abrasion resistance.

If you keep the window blinds on all the time then abrasion from lines is less likely but you may get abrasion from the blinds themselves - but is that a big issue?

If you take the blinds off to sail then flogging sheets can cause marking (but given the sheeting runs much less so on a Knysna than an Allures).

I would also look at additional reflective films - or maybe the printed dot type films. Serving two purposes - firstly a sacrificial layer for abrasion but also internal temperature control.

As to fitting - beyond the normal marine goops (Sikka do some specialised products for this), there are options using super-strong adhesive tapes that are now being used in vehicles (I think KYC were investigating this). There are also flexible adhesives used for putting windows into skyscrapers and vehicle windscreens. So plenty to research.

Obviously whatever adhesive you use it must be compatible with the window material you choose and may require a primer.

Another thing to be aware of when using the various adhesive sealants is to ensure the bed of cured adhesive is deep enough to allow for flex without breaking the bond. A friend on a Moody really struggled with his side windows with bonds failing because the design simply didn’t allow enough depth of adhesive to create a flexible bond - so the bond failed. Check the adhesive spec carefully for the minimum depth.

As to cost… 70k versus 4k!! I assume NZD not that it matters. If you took 70k and invested it at a 5% return you could replace the windows in plastic almost every year and still have your original 70k !!

If it was me, I would definitely go with plastic - glass windows worry me…

I hope that helps.

[Mike_Rose]

Thanks for your thoughts.
We have decided on plastic windows. We will keep this thread updated with the process, as it may be of interest to someone in the future…