Having just purchased Parker 21/8 I am looking to replace the main cabin windows. These appear to be machined from 8 mm Perspex, bedded in butyl rubber and attached directly to the GRP using No6 x ¾ inch self-tapping screws. These are countersunk screws and have matching countersinks in the Perspex so that the screws are under flush when fitted. I have approached Eagle Windows to make replacements but they have advised me against using countersunk screws as this may cause the Perspex to crack in the area of the screw. There does not seem to be any cracking on the windows I will be taking out!
I could ask them to make counterbores and use pan head screws instead.
Has anybody had experience of this and perhaps advise of the approach they adopted?

I replaced both windows over the last few years. I also bought the perspex from Eagle. I then cut the correct profile using a jig saw having clamped the old window to the new perspex. This also allowed me to drill the holes in the correct positions.

I was also advised to use pan head screws. I think this is sound advice: countersnk screws must create a lot of stress, particularly if the screws are tightened to try and prevent leaks. There were several cracks, starting at the screw holes, in mine. The proud pan heads have not been a problem.

I bedded the windows in Sikaset marine sealant, and they have been watertight so far. I also put a bead of sealant around the edge of the window -rather like we do in bathrooms. I thought that when they leak in the future, it would be easier to replace the bead than to re-seat the whole window.

Overall, it was a fairly quick and easy, and so far successful, job.

My Parker 21 No 30 has pan-head screws with no counterbores, they just stand a bit proud but no problem! My windows were bedded on an adhesive foam which eventually squashed down and leaked. I took the windows off and rebedded them on some grey mastic stuff I got at a boat show. That seems to have stopped them leaking. I do still have to tighten the screws up now and then and some of them are beginning to strip. I expect to have to replace them one day with bolts in holes drilled right through with nuts on the inside.

Update on changing the port window on 21/8, this was not an easy or short job!
I wondered why the window was cracked in the 1st place and am assuming that a previous owner tried to stop a leak and broke the window in the process as the non-viewing part of the window was attached by a very 'sticky' soft rubber across the whole area making it very difficult to get off.
After 2 hours of fighting I eventually managed to remove the window (in pieces) and am now considering the options for replacement. I could obviously retain the current method or just seal around the edges.
I am assuming though that the original method was employed to maintain an even black colour across the whole surface otherwise. As with taped edges only you may be to see the white grp below? The main viewing window area seems to be sealed with the same black rubber but as a tape.

Geoff/Jeff were your windows attached like this? I cannot image they were as this job was far from 'quick and easy'.


Any member advice would be very welcome.



The extent of the black sealant/adhesive that attached the window to the cockpit:-



The residual sealant/adhesive remaining on the cockpit:-



The window removed in pieces:-

Hi Alan, The P27 area has a similar thread running
cheers
Chris

The bit of the window which is forward of the coachroof aperture on mine is painted black so as not to show the white underneath. It all came off by gravity as soon as I took the screws out! Later 21s don't have the dummy bit of window ahead of the cutout.

As Chris says there is a window thread on the Parker 27 chapter of this parish - maybe this should all be in the "Other Tech Issues" section - I remember my Sinbad had the same window system and they never leaked even though they were underwater on a hard beat. I remember Jill complaining that she could see fish from down below!

There is a rubber sheet layer on mine, similar to yours It was in much better condition and I left it there, applying the sikaset sealant onto the rubber.

I have been told that we can buy sealing gasket material, although it is expensive, and I wonder if this is what the sheet rubber is. Anyone know about this?

Sorry this is not more helpful.

Hello Guys

Thanks for all of the helpful advice. I will be talking to Eagle Windows about what sealing options they recommend, also the information on the Parker 27 thread was very interesting and worthy of following up.

Alan.