Resealing classic Cheoy Lee windows - butyl/tape/silicone/hdpe dilemma

[wixlandia]

We are re-doing the portlights/fixed windows on a 1980 fiberglass yacht manufactured by Cheoy Lee. All were leaking at the time of purchase, and seemed to have some kind of ancient putty various sealants applied at the margins.

She has two window types - fixed portlights in the main cabin, and opening portholes of anodized aluminium design.

The former are installed in a 'sandwich' configuration with a profile cross-section in the attached image, with the glass captive between external and internal wooden frames that are attached to the margins of the cutout, but the glass is not unfortunately not directly compressed against the hull in any position. The internal ply fascia has been replaced, and sealed to the GRP with butyl tape. The wooden frames have been completely stripped and redressed. The glass has been replaced.

At this time, just the internal frames are installed, with butyl tape at B and C, and no signs of leak from B or C at all.

The glass can be placed in the cutout, but sits pretty loosely and the space between external frame (when dry fitted) and glass at D and internal frame and glass at F is quite large about 4mm on both sides - i.e. the window is not compressed in place by the frames. Our initial intention was to bed the window with butyl but a temporary fitment with butyl at E and F, without the external frames yet applied (shown in the picture taken from inside the cabin) has the window glass slumping to the bottom, and rain already in between glass and internal frame at F.

I figure we need to end up with some kind of gasket style seal bridging D, E and F with the external frame providing some moderate level of compression - but the butyl seems too gooey to do this.

Current plans involve using pieces of butyl tape as 'stand offs' at E to keep the window settled, then copious butyl sealant at F E and D and then maybe butyl tape or PE tape applied to the inner lip of the external frame at D to try to get some gasket style compression... it's not beautiful .

We could use a polyurethane sealant, but it'll be so hard to remove or repair in future - and we were keen to find a butyl solution.

Any help much appreciated.

 

[wreglesworth]

Hi - I found your post - I have a 1968 Cheoy Lee Offshore 36 with similar leaking windows. The teak veneer on the interior is also quite stained. I am thinking this is a perfect winter project. Please share any additional thoughts/ discoveries you might have. I would have thought that the windows were installed from the outside but it sounds like yours are held in place only by the teak frames. Thanks! - Jonathan

 

[BabaYaga]

The glass can be placed in the cutout, but sits pretty loosely and the space between external frame (when dry fitted) and glass at D and internal frame and glass at F is quite large about 4mm on both sides - i.e. the window is not compressed in place by the frames. Our initial intention was to bed the window with butyl but a temporary fitment with butyl at E and F, without the external frames yet applied (shown in the picture taken from inside the cabin) has the window glass slumping to the bottom, and rain already in between glass and internal frame at F.

I figure we need to end up with some kind of gasket style seal bridging D, E and F with the external frame providing some moderate level of compression - but the butyl seems too gooey to do this.

Current plans involve using pieces of butyl tape as 'stand offs' at E to keep the window settled, then copious butyl sealant at F E and D and then maybe butyl tape or PE tape applied to the inner lip of the external frame at D to try to get some gasket style compression... it's not beautiful .

We could use a polyurethane sealant, but it'll be so hard to remove or repair in future - and we were keen to find a butyl solution.

I faced a somewhat similar task earlier this year, and asked for (and got some good) advice in this thread:
Alternatives to silicone – butyl...or something else?
Your window construction is not exactly like mine, but I think there are some similarities. So I have a few tips that might be useful.

Firstly, I ended up using butyl, in two forms. 1) Butyl sealant from a cartridge, applied by a standard gun, to fill the void between the glass and the surrounding wood of the coachroof side. 2) Thin butyl tape (just over 1 mm thick) as a gasket on the inside of the metal frame.
This worked out well, no leeks so far. Of course, excess sealant was squeezed out over some time, but could be easily removed.

When installing, I had the same issue as you outline (if I understand correctly) in fixing the glass in place while at the same time compressing/bending it to fit in the opening. As "stand-offs", I used small bars of "chop-board plastic", four to each window, to keep the glass from sliding out of position. For compressing/bending, I used two "glass-lifters" (don't know the right term in English) on the inside, as can be seen in the photo.
This meant that the sealant could be applied and the frames screwed down with the glass already held in the correct position.

 

[billcole]

I used two "glass-lifters" (don't know the right term in English)

Yes you do...that is the right term !
Elegant idea too !

 

[wixlandia]

Thank you for all the replies.

BabaYaga, that's very nice. We don't have any metal frames on these (it is a sandwich of wooden frames inside and out, which means quite irregular surfaces).

In the end, we made a gasket of butyl tape between the inner frames and the hull, then a bead of liquid butyl from the outside, all the way around the inner frame, then the glass with small bits of butyl tape on the edges to hold it in place, then another bead of butyl circumferentially, then the external frames with small bits of butyl tape to help 'compress' the glass. So far, no leaks.

Learnings:
1) Extremely time consuming
2) If we do it again, we'll replace the windows with acrylic or polycarb cut larger than the cutouts that is compressed against a gasket from the outside of the hull with bolts and a trim, rather than this 'floating' glass design. Or may even put in pre-fabricated windows by just altering the fiberglass cutouts as required
3) We should have used skinning butyl, as there is some water staining on the outside of the glass after rain with small amounts of butyl residue - hopefully this is not an ongoing feature
4) Not worth it - replace windows or make a modern style such as acrylic or polycarb sandwiched from outisde