I would personally recommend Silpruf. My understanding is that it was designed to put windows in skyscrapers and it has 100% elasticity. When we put windows in the SC 50's, the rig shop I worked for was the only one I am aware of that would guarantee the window installation. I would recommend black for the color. Takes more to cleanup but looks better overall IMO (Looks like a shadow line vs dingy white after a number of years).

https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Doffi...

The key is to have some space like Brendan mentioned. I use small nylon washers on either side of the bolt holes to maintain the gap vs E-tape.

The key is to only tighten the window so that it is snug (less is more in this situation) and not to over-tighten. Oversized holes in the windows is key as well like Brendan mentioned. Once everything has cured, you can tighten the bolts a bit more but only tighten the barrel nut on the inside. You want to take care not break the seal on the outside. You likely won't need to do this but if you do, then that is how I would do it.

If you do the job, I would highly recommend you do new windows as well. It is a big job and you wouldn't want to make the effort without new windows IMO. It would probably take me 6-10 hours for the 4 windows in the Express to do it right and I did a lot of windows back in the day when I worked as a rigger.

SC 50 was 8 hours per 8ft window for reference. That is a pull, prep and seal new windows in.

Jason

:: I don't use acetone on the windows but have not observed
:: any visible harm for use on gelcoat. More harmful to
:: lungs & tissue.
::
:: Next time, I may try what I've seen on Yeti, a foam
:: automotive like weather seal. Also, if you are in a jam,
:: blue tape the window edges before a race or use Stay
:: Afloat puddy (smells like jerky) if surface is dry or
:: wet. Jam into joints or cracks.
::
:: JB
::
:: :: Tell us more about NOT using acetone or solvents. What
:: :: should be used and why no acetone or solvents. SDK
:: ::
:: ::
:: ::
:: :: :: No posted instructions that I know of, though you can
:: :: :: search the internet and find various approaches people
:: :: :: have taken.
:: :: ::
:: :: :: Generally windows leak through the screw holes, though
:: :: :: if not well sealed originally they can leak anywhere.
:: :: :: The cabin top flexes a lot when walked on and will break
:: :: :: the seal for the windows. If the windows are in very
:: :: :: good shape and seem well sealed you can try removing
:: :: :: offending screws, sealing them with silicone, and
:: :: :: replacing them.
:: :: ::
:: :: :: To re-bed the windows they must be removed, all old
:: :: :: sealant carefully cleaned from boat and windows
:: :: :: (difficult as you should avoid using acetone or solvents
:: :: :: to clean the boat or windows), and then resealed. It may
:: :: :: be a good time to replace them--if you take the old
:: :: :: windows to Tap Plastics they will fabricate new windows
:: :: :: for a very reasonable price. Have them drill the screw
:: :: :: holes also (oversize to allow for expansion), as
:: :: :: drilling through lexan without a proper drill will cause
:: :: :: micro cracks that spread later. Note that Tap will bevel
:: :: :: and/or melt edges to your specifications for a very nice
:: :: :: look.
:: :: ::
:: :: :: After breaking several windows during races, I switched
:: :: :: to polycarbonate windows, which scratch more easily but
:: :: :: are much much stronger.
:: :: ::
:: :: :: When re-bedding windows, you want to have a good
:: :: :: thickness of silicone. One trick I learned for this is
:: :: :: to cut tiny squares of white electrical tape and placing
:: :: :: them near (1/4" away from) the screw holes, so when you
:: :: :: fasten the window in place there is still a thickness of
:: :: :: silicone to make the seal. Don't tighten the screws
:: :: :: until the silicone has set up somewhat, and then don't
:: :: :: tighten them very much. Remember, you want a thickness
:: :: :: of silicone to make the seal.
:: :: ::
:: :: :: Masking over everywhere that silicone should not go
:: :: :: (window, cabin top) is a good idea, as silicone that
:: :: :: gets loose will both make a mess and make future
:: :: :: painting / repair jobs go poorly.
:: :: ::
:: :: :: I have an Express 37 with the original windows (very
:: :: :: hazy but no leaks). They have very thick silicone layer
:: :: :: (perhaps 1/8" thick). I'm not sure what trick they used,
:: :: :: but it has been very effective over the years.
:: :: ::
:: :: ::
:: :: ::
:: :: ::
:: :: ::
:: :: :: :: Where can I find how to repair Express Window water
:: :: :: :: leak?
:: :: ::
:: :: :: :: I heard it is common for Express 27. Any article or
:: :: :: :: instruction for the repair?