Fitting new cabin windows

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grahamclive

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26 Mar 2008
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Hello All,
I am looking for some advice on fitting new window glass to my Holman 26'. The cabin sides are teak with a 6/7mm deep rebate on the inside face for the glazing (4mm toughend glass) . Teak trim pieces and plenty of woodscrews hold the glass in place. The seal appears to have been white lead putty, but this has deteriorated with age resulting in wet bunk cushions etc. I am wondering whether anyone has experience with the modern sealants such as sikaflex, arbomast etc. From the tech literature I have seen, there appears to be no single product that fulfils all the requirements i.e. sticks effectively to glass, teak, is resistant to UV light, able to form a good seal in such a small gap etc.
Perhaps its best after all to use the traditional stuff, but any suggestions would be most welcome.
 
My formerly leaky windows sound similar to yours except the rebates are in the outside of the cabin and the windows are held in by S/S frames and lots of screws. I was advised to use Marineflex Bedding Compound available here. It's a non-setting polyurethane which means it sticks and stays stuck, you just have to be careful to clean all the exposed sealant away once the joint is made. I rebedded my windows a month ago and so far so pleased, it seems to be a lot more waterproof than the previous arrangement which I think was some sort of silicone rubber.
 
As an alternative to mastic-type goo you could try EPDM dry glazing tape, such as that stocked by ironmongerydirect.com. This is a dense foam rubber self-adhesive tape which is aplied to the rebate to form a gasket. I use it to install double glazing units in timber frames (on land!) and have had good results. It's a lot quicker and cleaner than mastic, and it remains flexible over time.
If you do go down the mastic route I'm a fan of polysulphide sealants, such as Arbokol. One common cause of failure with mastic seals is squeezing the joint up too tight on assembly. If the mastic film ends up too thin then the material can't accomodate the shearing forces involved due to differential movement, and the joint fails. It's important to design in a suitable thickness of material - this might involve creating a groove in the rebate to contain a bead of the mastic.
 
Our windows are fixed in much the same way. I opted for the foam tape. My windows fit flush once clamped onto the seal, I used 3mm thick seal (6mm polycarbonate windows). I was a bit dubious because the width of the seal surface is only 10mm but we have had no problem so far. Certainly beats the gooey stuff!!
 
Arbomast BR (butyl rubber)

To clean off easily.......make up a sharp chisel-pointed stick, spray
stick, windows and surround with white spirit, remove excess sealant with stick as if a chisel and catch the excess on a bit of ply or card.
Respray with white spirit and rag off remainder.

White spirit in a spray gun (ex kitchen cleaner) is SO handy!
 
I am in the process of doing this on my Falmouth Pilot. I have had to replace the whole cabin side which includes two windows. These were sealed by a u section channel section, long since deceased and possibly the cause of the rotted plywood. I thought that the seal section might be unobtainable but Seals Direct came to the rescue and I am about to fit them back. The outer trim is a stainless steel collection. If you hear a scream, they wont' fit!
 
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