Boat windows questions

[Boo2]

Hi,

I have been meaning to replace my main saloon windows (see pic below) all year and have just had a look at how they're fastened. There are interscrews in the coachroof sides but they are longer than the solid grp sides are thick and so protrude into the cabin by 4mm or so. The excess length being compensated by holes relieved into the outboard sides of the headlining in that area.

When I come to replace the windows I have the choice of trying to undo the screws carefully enough that the screws + interscrews can be used again or alternatively I could drill them out and replace with new, shorter ones that are a better match for the thickness of the coachroof sides. Any ideas which of these tactics is likely to prevail ? The windows are presumeably 35 years old now and the screws have most likely never been undone in that time so I'm not super-optimistic about the chances of getting them out intact...

The alternative would be to accept that the old screws have had it and get the new windows made up with screw holes in completely different positions and put new screws + inter screws in. Or an alternative might be rivnuts but they are presumably not watertight if the sealer fails ? Or through-bolt ?

Anyone know what is likely to happen and what is the best way forward ?

Thanks,

Boo2

View attachment 35096

 

[VicS]

we took ( some of) the windows out of a Westerly a few years ago. I dont remember any great difficulty in removing the interscrews but a number were not reuseable.

They were an odd size that Westerly used at one time and only available, as far as we could find, from Trafalgar yacht services. They were expensive but not as expensive as new frames would have been.

 

[yoda]

The deciding factor may well be getting the old windows off in one piece. If you do then making new ones with the holes in the same place is possible but otherwise you will almost certainly not achieve it. It would be wise to reuse the old holes if at all possible. When I did mine the issue was finding a way of getting the pull down required without cracking the acrylic as the coachroof is curved. Yours doesn't look too bad but it still looks like the interscrews have a flat head or washer to avoid a point load when tightening. Do you have to remove the headlining to get to the inside? If so then Nuts and Bolts would be the easy way forward. If the inside shows then you could use Chrome Dome nuts. Also I used a butyl mastic strip to bed the windows - undoubtedly saved me time, money and leaks - so much better than trying to use tubes of sealant.

Yoda

 

[rbmatthews]

Also I used a butyl mastic strip to bed the windows - undoubtedly saved me time, money and leaks - so much better than trying to use tubes of sealant.
Yoda

Do you mind saying what butyl mastic you used? I have tried Sikalastomer 710 and Arbomast BR Black (both butyl rubber) on our windows over the years and neither have lasted much more than a year before starting to leak again as it does't bond well to the acrylic. I am going to have to do them again this winter and am just considering which options. Butyl rubber is certainly much easier to use than an adhesive like Sikaflex 291, but if it doesn't work ...

Rob.

 

[Talulah]

You'll need the longer screws to pull the windows in and squeeze out the sealant. You could use the old screws for this then replace with new shorter screws for the last bit of squeezing.

 

[ianj99]

Do you mind saying what butyl mastic you used? I have tried Sikalastomer 710 and Arbomast BR Black (both butyl rubber) on our windows over the years and neither have lasted much more than a year before starting to leak again as it does't bond well to the acrylic. I am going to have to do them again this winter and am just considering which options. Butyl rubber is certainly much easier to use than an adhesive like Sikaflex 291, but if it doesn't work ...

Rob.

Use caravan mastic. I tried it on the front wheel house windows and its been 100% effective for 2.5years so far.

It does not set or skin over and is easily removed with white spirit or if you need to remove the windows again.

http://www.caravan-components.co.uk...lant-Silicone-Mastic-Butyl-Tape/Butyl-Mastics

IDL99 £2 / tube

Ian

 

[PCUK]

You can use stainless self tappers into the fibreglass which will have more than enough strength. Make sure the holes in the acrylic are larger than the screw diameter to allow for expansion and avoid cracking. Also place a washer over the screw behind the acrylic to hold it slightly off the GRP as this avoids squeezing out all of the mastic when tightening.

 

[Deleted member 36384]

Do you mind saying what butyl mastic you used? I have tried Sikalastomer 710 and Arbomast BR Black (both butyl rubber) on our windows over the years and neither have lasted much more than a year before starting to leak again as it does't bond well to the acrylic. I am going to have to do them again this winter and am just considering which options. Butyl rubber is certainly much easier to use than an adhesive like Sikaflex 291, but if it doesn't work ...

Rob.

I used Arbosil GZ Mastic Strip, going on 3 years now for the first batch of windows that were refurbished first with no leaks so far; the frame to GRP seal. On a framed window you have to be sure that the glass to frame seal is 100%. If not then the frame will leak through the frame joint or in some cases pitting corrosion holes in the frame itself. On my own windows the glass was sealed into the aluminium frame with Sikaflex (the one designed for mineral glass) as part of the refurbishment as the O ring seal had perished; it is an inferior sealing method compared to modern adhesive mastics for setting glass inside aluminium frames.

http://hadlo-43547-001.dsvr.co.uk/Pages/Sealants.html

Boo2 the above is for framed aluminium windows, I do not know if it would be suitable for direct mounted perspex windows.

 

[jakeroyd]

Just to follow up the sealant question , if you need to use it. see here
http://www.ybw.com/forums/showthread.php?363505-Leaking-windows-Grr-Grr-Grr&highlight=jakeroyd

Note Sika 291 is not the best to use for windows due to it's relatively low rsistance to UV.

 

[Stemar]

When I refurbished my windows, I used a self-adhesive neoprene from Seals Direct with no leaks (touch wood) for 7 years. This was with framed windows, but I've often seen very scruffy-looking unframed ones and thought that painting the back of the window where it overlaps the GRP and using the neoprene could make a very tidy job. It has the advantage that it doesn't adhere to the boat, so the widows can be removed easily should it be necessary.

Incidentally, I had the problem of pulling the window down onto a curved cabin. I used long bolt to pull it in, then went changed them for shorter ones with dome nuts, as they're visible inside. It looks a lot tidier than the original with interscrews in a tatty bit of wood.