Given we make you do this it only seems fair we give you some guidance...
Jump to whichever part you need help with;
Part 1 - Removing a framed window
Tools required: Masking tape (19mm or 25mm), screwdriver, combination pliers, 2”-3” good quality filler knife/scraper and lightweight hide or nylon mallet. A variety of thin wedges are useful too.
The first thing to try and work out is what is holding the window in position. If lucky it will be old bedding compound which will give way so easily as to appear to welcome your efforts with open arms. If the windows have been in for 15+ years this is a likely situation. Alternatively, if nursed from the dark side, ie installed with the devil's own gunk (sikaflex or silicone) then you may regret (more) the day you became your fine boat's custodian. The devils gunk is an adhesive, probably a very good one which like a killer shark will fight you for every mm of movement. Good luck! In contrast (take note for re-installation) bedding compound is designed to seal, but let go...
Let's assume you are lucky....
Using the masking tape, label the windows and the inner trim rings (if fitted) to include location and orientation, e.g. STBD AFT ? Loosen the screws all the way round the window – if you have inter-screws (threaded sleeve nuts) fixed to the trim ring inside your boat, you may need the help of someone to hold them with a screwdriver or pliers to stop them from rotating (or like many they may refuse to move even when the windows are out).
Remove all the screws in pairs that are diagonally opposite each other. Remove any other fittings or attachments that may impede your access to the windows. The trim rings will now be loose and will drop down so be aware of any potential problems e.g. the headlining may be attached to them or they may scratch some wooden interior fittings.
Using the mallet, gently tap the filler knife into the joint between the window and the GRP/wood of your boat. It is best to only tap the filler knife in about 1/8” or 3mm and work your way around the whole window. Repeat this several times until the filler knife comes in contact with the inner flange of the window frame. If your window is a piece of Perspex screwed directly onto the boat, the filler knife blade should be visible from the inside of the boat. If your windows have been sealed with an adhesive type sealant, you may need to insert a long thin blade into the joint to cut the sealant.
Your windows should now be ready for removal. If it does not come out readily, someone on the inside can assist by gently pushing from the inside. On no account should you use a screwdriver or other tool to lever the window out – it will result in damage to your boat and window. If using the wedges, make sure they are evenly distributed so as to avoid any bending of the frame.
Count and store all the trim rings and fixings until required again for re-fitting the windows.
Don't fall into the trap of thinking that was easy, I'll just take them apart a bit... We won't give a discount if they arrive in bits as we then have to work out what goes where and we still have to clean even if you think you have. It's our reputation....
Part 2 - Refitting the window
To get you in the right frame of mind : be aware that the most common fault when refitting windows is finishing with insufficient bedding compound between the frame flange and your boat. Things normally start well with a nice bead of compound on the flange prior to fitting so where does it go? The most common culprit is you and your desire to make sure the fixings (screws/bolts) are tight. Just a little more often results in all the compound being squeezed out. Another culprit could be the guy who laid up your hull moulding or repaired the cut-out after a Friday afternoon jigsaw fest following a boozy lunch. If there are hot-spots (ie raised areas) on your hull, or if your frame is bent then clearly some areas may suffer more of a squeeze than others. The latter you can check for in advance, the former, now knowing the issue, you can take steps to avoid.
If you have hot spots, make sure these retain adequate compound, even if this results in more in other areas. You can rarely have too much, but too little will leak.
Next, how to avoid squeezing too hard. The rocket scientists amongst you will see two obvious options; One, is to refrain from screwing too hard, checking that approximately 1mm of compound remains between flange and hull. Two, is to position something of the required thickness between the flange and hull so that you can't squeeze tight. There are two favoured approaches: One, supplement the tube based bedding compound with the tape based equivalent (GZ tape). This comes in rolls and is nominally 10 x 3mm, but when compressed closer to 12 x 1mm. Rarely possible to compress beyond 1mm, this will ensure you have 1mm of compound around your window. Given the tape goes all the way around this also deals with hot spots too. Two, use pieces of chocking rubber (1mm), placed on the flange (inboard closest to pane). The potential downside with the rubber option is that unless your cut-out is a close fit to your frame there is a danger that the rubber may end up pushing against air. It also fails to deal with hot spots unless placed close to high areas.
Note that some flanges contain recessed areas/channels to hold compound even if the flange is closer to the hull. The same normally applies to the base plates on Hatches.
Now let's get on with the process...
The notes below refer to sealing the window with the non-setting bedding compound as supplied by Eagle Boat Windows, which is recommended for this application. This is the grey ARBOmast BR butyl compound supplied in 380ml tubes. Do not use an adhesive based sealing compound (like Sikaflex) as this will cause problems and prevent you from later removing the windows without damage to the frame and the boat (as warned above).
Check the fit of the window in the aperture. Carry out one or two “dry” fits of the window using all the fixings and inner trim rings (if used) to make sure that there are no problems. Remember to look for high spots.
If using the butyl (GZ) tape as well as the compound, place the tape on the inside of the flange closest to the pane. You will put the compound on the outer side of the flange. Do not put compound on top of the tape.
To fit the windows, cut the nozzle at 45°, and apply a 6mm/¼” bead of bedding compound in line with the screw holes (or slightly outside if using tape as well) around the inside of the window flange that butts against the GRP/wood of your boat.
Present the window to the aperture (remember orientation!) and press it against the boat. You will see a witness of bedding compound appear in the holes where the screws locate. If your windows are fixed using inter-screws, you must remove the witness of bedding compound otherwise it will be trapped in the inter-screw and you will not be able to tighten the screw correctly. Insert the screws and tighten very lightly around the window. Working your way around the window several times, tighten the screws so that there is only a small gap (1-2mm) between the frame and the boat. Do NOT overtighten! If you squeeze all the compound out there will be nothing left to seal and/or prevent leakage.
Leave the witness of bedding compound to harden for a few days and then, using the small plastic scraper supplied, peel off the excess compound. If there are any stubborn remnants of material, use a soft cloth and White Spirit to remove it.