Window refurbishment – a commendation, a few hints and an enquiry

[Hydrozoan]

Having just removed a saloon window for refurbishment, I thank PBO and the author for this well-illustrated and helpful article: https://www.pbo.co.uk/expert-advice/renovating-boat-windows-27718. It is I think likely also to help owners of other Sadler models, and perhaps of other makes too.

A few hints:

(1) As well as adding the protecting tape on the stripping/filler knives as shown, I also ran a length on the coachroof side around the edge of the frame.

(2) Getting a knife into the lower edge of the frame to cut the sealant to the coachroof was difficult because of the limited space above the side deck. An old table knife with a flexible steel blade, honed near the point, was very helpful there.

(3) For the same reason, prying the out the bottom of the frame was difficult, yet necessary because the frame was a tight fit in the aperture and had to come out square. I resorted to inserting a large wood chisel sideways into the ends of the lower frame and gently twisting it. To try to avoid this next time, I shall make up a few small J-shaped aluminium pry bars and hope that by inserting the (sharpened) short end of the J upwards under the frame they can be levered gently against the coachroof side below, to help pry it out evenly.

I will now reset the glass in the frame, but have an enquiry about sealing the frame back into the GRP. The article and other accounts I have read recommend Arbomast BR butyl sealant and that is probably what I shall use. However, one hears also about butyl tape for sealing deck hardware and I wonder if anyone has used it for sealing window frames into GRP? My reservations are that it may not be thick enough, and that it may not be possible to get it round the tight bends without introducing vulnerable joins. Any experiences would be much appreciated.

 

[Stemar]

If, like me, you have to bend the window into a curve as you tighten it down, you may find you squeeze out more butyl than you would like in the middle.After fighting leaks on windows 130 cm long by less than 30 high for more than 10 tears, I cut off the part of the frame that held the perspex, making an l instead of an h, so the frame is now simple a decorative trim. New perspex is bolted through this trim, with some neoprene to prevent it scratching, the perspex, butyl tape, the cabin side and a new wooden trim (3mm ply). The result looks good - not significantly different from the original design - and, most importantly, is waterproof.

 

[Hydrozoan]

Thanks, Steve. I don't think there is much visible frame curvature from side to side (perhaps more on the larger windows, which I have yet to tackle) but the article to which I linked does refer to using small pieces of ca 1mm thick Firestone EDPM roofing material in the centre section to avoid the Arbomast sealant being preferentially squeezed out there as the screws are tightened. (BTW it attributes that hint to the PBO forum, in a post or posts I must have missed!)

Getting an even thickness of sealing around such packers is perhaps another reason not to use butyl tape, however – so thanks again.

 

[Deleted member 36384]

.... However, one hears also about butyl tape for sealing deck hardware and I wonder if anyone has used it for sealing window frames into GRP? My reservations are that it may not be thick enough, and that it may not be possible to get it round the tight bends without introducing vulnerable joins. Any experiences would be much appreciated.

My windows (aluminium framed, similar to the ones in the PBO article) were refurbished by Hadlow Marine. They were returned with Scapa 3507 bedding tape, 3mm thick, see link below. This is a foam tape which is not sticky like soft butyl. Some of my windows have a small compound curve (fore and aft as well as athwartships). The foam is not sticky and requires compression to make the seal. The earliest refurbished window has now been in place for 5 years and has been heavily tested in extremes of temperature (-17 to +25 Celsius), heavy rain, power washing, wave slap. Not a drop of water has passed the frame to hull seal (or glass to frame seal).

Fitting was easy: make good any damage to the GRP, fair, clean with solvent, offer window up to aperture, fit screws lightly, tighten flange evenly in steps by adjusting opposite screws alternatively. The screws were tensioned so that there was a slight bulge of tape protruding from the frame / GRP interface.

http://hadlowmarine.com/Pages/seals-bedding.html

 

[Hydrozoan]

Thanks BOB - that looks very interesting, and your experience is certainly encouraging. Definitely a possible alternative – it sounds a lot cleaner to use than ‘liquid’ sealant.

I see it compresses down by 30% from 3mm to about 2mm, and it would presumably easily cover the 1mm side-to-middle frame curvature implied by the use of 1mm central EDPM packers in the article. The existing sealant on the outside was less than 1mm, but a bit more unsightly reveal on the inside could be dealt with by a larger bead of internal sealing. I might need slightly longer screws, but am in any case intending to epoxy wood plugs into the existing screw holes to ensure a secure hold.

PS The Sadler frames are very tightly curved at the ends, as the pictures in the article show. Do you think that might be a problem for the Scapa tape?

 

[Deleted member 36384]

.... PS The Sadler frames are very tightly curved at the ends, as the pictures in the article show. Do you think that might be a problem for the Scapa tape?

Some of my frames are curved but two of the longer saloon window frames were not, although the ends over lapped the curved coach roof. The screws pulled these frames into place to match the curves. The foam was compressed to about +0.5mm at the edge of the frame, where the curve started and about 2mm where the frame finished around the curve. So far water tight. The foam material is supposed to have a fair bit of tenacity / resilience i.e. it wants to return to its original shape. The foam is also available in 6mm thicknesses.

 

[Hydrozoan]

Some of my frames are curved but two of the longer saloon window frames were not, although the ends over lapped the curved coach roof. The screws pulled these frames into place to match the curves. The foam was compressed to about +0.5mm at the edge of the frame, where the curve started and about 2mm where the frame finished around the curve. So far water tight. The foam material is supposed to have a fair bit of tenacity / resilience i.e. it wants to return to its original shape. The foam is also available in 6mm thicknesses.

Thanks - I was wondering if one would need to snip triangles from the inner edge (I can't think of a technical term for that!) to keep it flat on a curve of about 6cm radius.

EDIT: I should have explored Hadlow's site further - its guide to using Scapa tape actually suggests that technique for tight curves (but does not say how tight - I may call them for advice) and also shows interlock techniques to make joins. http://hadlowmarine.com/Pages/Fitting acrylic windows.pdf

 

[UK-WOOZY]

for my 1988 jeanneau sundream the side windows are 6mm, the front is curved 12mm. Jean Pierre at Hadlow (his house) recut new ones using the originals and drilled the holes and supplied the foam bedding tape and interscrews. the screws werent suitable so i used slotted interscrews from seascrew. along with the foam tape, i also used dow corning marine sealant on the outside for a beed and used arbosol in the screw holes. the frames are alu internally. fitted them during the cold wet winter at the beginning of this year, was worried about the front acrylic cracking when having to force it aound the front curve, but hadlow assured me didnt need to heat it and he was right, started in the centre and bolted outwards each side equally. took a very long time though to do everything. cost of the acrylic and fittings exl the other screws i got from hadlow was £600

 

[Hydrozoan]

I have decided to use a slightly thinner (2.5mm) version of the Scapa 3507 tape for sealing the frames to the coachroof sides, and Arbosil 1096 for the glass to aluminium joint (and for the frame fishplates and screw sealing). I have also made my 'J-shaped tools' for prying out the lower edges of the frames.

My sincere thanks to all who responded.

 

[Keith-i]

A bit late to the party, but I've just refitted my windows with butyl tape. I struggled to decide between tape and Arbomast BR but eventually went for the tape as it has a bit more solidity and form to it. It went round curves with a 200mm radius without any problem and could probably go much tighter. If anything it was the backing tape that limited the curvature rather than the butyl itself. It is very pliable and so far seems to have done a good job. As my hull sides have a bit of curvature to them I felt the Arbomast would ooze out too much at the pinch points.

 

[Hydrozoan]

A bit late to the party, but I've just refitted my windows with butyl tape. I struggled to decide between tape and Arbomast BR but eventually went for the tape as it has a bit more solidity and form to it. It went round curves with a 200mm radius without any problem and could probably go much tighter. If anything it was the backing tape that limited the curvature rather than the butyl itself. It is very pliable and so far seems to have done a good job. As my hull sides have a bit of curvature to them I felt the Arbomast would ooze out too much at the pinch points.

My understanding is that the Scapa 3507 tape is not as 'sticky' as a butyl tape, and given BOB's experience of it I will give it a try, as likely easier to use (and more easily 'reversible') than a liquid sealant. I expect to have to apply it very carefully around
window ends with a smaller radius than 200mm, but the vertical and lateral curvature of the coachroof sides themselves is fairly small. We shall see - and thanks for coming to the party anyway!

 

[[3889]]

Having just removed a saloon window for refurbishment, I thank PBO and the author for this well-illustrated and helpful article: https://www.pbo.co.uk/expert-advice/renovating-boat-windows-27718. It is I think likely also to help owners of other Sadler models, and perhaps of other makes too.

A few hints:

(1) As well as adding the protecting tape on the stripping/filler knives as shown, I also ran a length on the coachroof side around the edge of the frame.

(2) Getting a knife into the lower edge of the frame to cut the sealant to the coachroof was difficult because of the limited space above the side deck. An old table knife with a flexible steel blade, honed near the point, was very helpful there.

(3) For the same reason, prying the out the bottom of the frame was difficult, yet necessary because the frame was a tight fit in the aperture and had to come out square. I resorted to inserting a large wood chisel sideways into the ends of the lower frame and gently twisting it. To try to avoid this next time, I shall make up a few small J-shaped aluminium pry bars and hope that by inserting the (sharpened) short end of the J upwards under the frame they can be levered gently against the coachroof side below, to help pry it out evenly.

I will now reset the glass in the frame, but have an enquiry about sealing the frame back into the GRP. The article and other accounts I have read recommend Arbomast BR butyl sealant and that is probably what I shall use. However, one hears also about butyl tape for sealing deck hardware and I wonder if anyone has used it for sealing window frames into GRP? My reservations are that it may not be thick enough, and that it may not be possible to get it round the tight bends without introducing vulnerable joins. Any experiences would be much appreciated.

Not butyl but I successfully used this to seal windows on my Hunter 27.
They had acute corners, c. 45 deg, but partially cutting through the outer radius of the bend allowed a single section of tape to be used. The fitting guide on the webpage shows how to make the single join watertight. Ive also used it to seal deck hardware.

Edit: Whoops. Should read whole thread first.

 

[captainboo]

Thanks - I was wondering if one would need to snip triangles from the inner edge (I can't think of a technical term for that!) to keep it flat on a curve of about 6cm radius.

EDIT: I should have explored Hadlow's site further - its guide to using Scapa tape actually suggests that technique for tight curves (but does not say how tight - I may call them for advice) and also shows interlock techniques to make joins. http://hadlowmarine.com/Pages/Fitting acrylic windows.pdf

I also had my widows done about 8 years ago by Hadlow and refitted using their tape. No leaks since refitting.

The tape will go round a tight curve, less than 6cm in my case. The technique I found that worked was to attach the tape along the straight edge towards the curve and then only the edge of the tape along the larger outer radius first allowing the 'excess' tape to bulge up along the inner edge. Press the tape down along each flat section towards the curve to fix it firmly in place and then working from the outside of the curve to the inside press the tape down. This will cause the tape to compress along the inner curve and it should lay flat quite happily with no wrinkles. Do not stretch the tape at all anywhere to make it fit when attaching as it will only shrink back over time!

 

[Hydrozoan]

Thanks to you both – slightly different techniques, and I’ll see what works best on my frames, but it’s good to know from a number of people that the Scapa tape works well, and I take the point about not stretching it.

 

[Hydrozoan]

A brief update as I’m now on the second, larger window. After knifing away accessible rubber seal, the article advised clamping one end of the window and malleting a filler knife inserted between the glass and frame at the other end to split the frame. That did not work well for me, so I made up a simple puller from a long bolt carrying a plate hooked under the frame end, and that split the frame very easily and controllably.

I am using Arbosil 1096 rather than a two-part putty for the glass to frame seal and although it’s an art getting a well-shaped bead on the outside face, one improves with practice. The 2.5mm Scapa tape needed only small radial cuts to sit flat on the curved frame ends, and it made refitting the windows very easy indeed. Sealing only against the coachroof sides also enables me to use only a cosmetic bead of silicone inside, and having had to knife out an awful lot of silicone from the reveals to free the frames, that is a big benefit - albeit I hope to the next owner, not to me!