The following was sent to me for a 2009 B40 Cruiser leaking forward hull window.
Solution.
Remove plastic insert. It is attached with Velcro.
Undo bolts and remove window completely (you will require a person in the dinghy or on a wharf to assist or it could drop out)
You will find that the hatch was sealed with a foam tape.
When window is removed place on flat surface and fill with water to test if window is leaking between glass and rubber.
If it is and the yacht is still under warranty it is best to request replacement window. Photos will be required to prove leak and serial number of window.
If yacht is not under warranty and you do not wish to purchase new window you can attempt the following. Undo the screws and carefully pull apart the window being careful not to bend the joiners.
When removing rubber from glass, be careful not to stretch or kink rubber.
Coat rubber in lanolin grease or silicon grease and re-insert around glass but be careful not to pinch rubber when sliding frame back into place, ensuring a good snug fit.
Do up frame and then test with water by filling frame and rubber with water and see if it leaks through.
To fit back into the hull, completely remove all foam tape and clean completely. Run a bead of sikaflex/silicon or similar around hull where frame will be inserted.
Insert Window into hull and do up bolts a bit at a time crossing diagonally from bolt to bolt. Do not over tighten or you will squeeze out all the silicon. Wait 24 hours and then hand tighten all bolts. (what you are trying to do is create a gasket and completely seal the window. There is always some flex in hull under sailing conditions and having sufficient sikaflex between the hull and the fame will allow flexing with out water ingress.
Replace plastic insert.
THe key step is to allow the silicon/sika/sealant to cure for 24 hours which creates a more flexible seal.
Cheers