you are unlikely to find what you are looking for in ready made form because it is not recommended that the large salon windows in a sailboat be openable....
over the years many boats have been sunk due to weak salon windows breaking out during a knock down to prove that a large open hole in the side of the cabin trunk is unsafe.... no manufacture wants to contribute to this by making large ones that open.
usually when owners want to replace the stock windows, they go the other direction that what you desire, as they will take out the stock windows and have thick plexiglass or lexan bolted in for strength and to insure water tightness for many years.
also, when making a window that has the ability to open, the larger the window is, the more prone it is to leak, and no reputable manufacture wants to produce something so expensive that they cant reasonably guarantee to be reasonably trouble free for the consumer....