Renovating boat windows
Bedding the refurbished frames back into the boat
Finally, the frames are re-bedded back into the boat hull. We prepared each frame for installation using one-pack
butyl sealant, which is essentially non-setting and can be cleaned up easily with white spirit
F
irst, check the fit of the
window and alignment of
screw holes in the hull
opening: thankfully all our
screw holes lined up correctly.
Despite our careful stencilling,
some of the hull window openings
still needed a couple of mm of
easing to enable the frames to fit
back in. I therefore made a small
tool to hold abrasive sheet from
a 10cm block of wood and some
old aluminium tile trim, which
happened to be the same depth
as the frame. Any additional
making-good of the opening was
also carried out at this stage.
Our windows have a slight
curvature, which immediately
straightens when you remove
the frame from the boat. There
is therefore a tendency for the
central section to be compressed,
squeezing out any sealant and
potentially giving rise to future
leaks. This didn’t seem an
attractive proposition after all
the hard work, so to avoid this
I decided to incorporate small
rubber spacers made of some
Firestone EPDM roofing material
I had been given. It was just over
1mm thick and was bedded in
the same butyl sealant a day in
advance of installation. Note that
this is a non-standard procedure:
however, reading the PBO forum,
some other people feel spacers
are desirable.
Each frame was prepared for
installation using Arbomast BR
(one-pack) butyl sealant. This
versatile material is intended forLESSONS LEARNED
1
Window refurbishment
is a lengthy and labour-
intensive job taking around
10 days (excluding curing
time) for six windows: just
cleaning the frames took
two days.2
Use a professional
resealing company’s
services if time is tight;
this then enables you
to concentrate on
removal/reinstallation.3
The two types of butyl
were pleasant but messy
to work with – prepare!4
Your technique will
improve as you do more
windows, so do the job in a
couple of batches.5
There’s more to this
job than meets the
eye, but it’s well within the
capabilities of a practical
boat owner!An ‘easing’ tool, about 10cm long,
adjusted the hull window aperture
The frames were inserted to check fit and hole alignmentOne of the window frames, cleaned up and reinstalled‘covered’ sealing applications and
is essentially non-setting, apart
from an external skin which
forms to a stiff chewing-gum-like
consistency after a day or so. It
cleans up easily with white spirit.
Cut the butyl nozzle at 45° and
apply a 6mm bead of bedding
compound on the inside of the
window flange in line with the
screw holes, forming a doughnut
shape around the screw holesA 6-7mm sealant bead was applied in line with the screw holes, forming
a doughnut shape around the holes themselves
themselves. Use a little more if
incorporating spacers.
Present the window to the hull
the right way up and gently press it
against the hull, which will create a
‘witness’ around the perimeter.
Remove any initial sealant
appearing in screw holes in the
frame before the screws are
inserted, otherwise a hydraulic
build-up of pressure in blind-ended
holes or inter-screws can occur.
However, you may also wish to put
a little sealant around the neck of
the screw to ensure an effective
seal. Carefully tighten the screws,
working around the perimeter of
the frame, doing this in rotation
several times until only a small gap
remains between hull and frame.
The butyl should not be squeezed
out completely or it will leak.
Screws should only be ‘nipped up’,
not fully tightened. Leave for a few
days to harden, then trim using a
scraper and white spirit.
So that’s that job complete. It
took longer than expected, but will
hopefully mean we’re watertight for
another 25 years. Now, let’s see
about re-bedding the hatch!Thin EPDM sheet roofing packers
(bedded in butyl) were used to
avoid butyl sealant squeeze-out