The porthole consists in a fixed part (frame) and a moving part (window).
For opening, it is necessary to unlock the window by turning the handles 90° outwards. Closing is done by means of a thick seal on the porthole frame.
It is necessary to make sure that the two knobs are correctly closed, in order to make the window seal adhere well to the frame.
The mosquito net (optional) hinders the sealing of the portholes, take it off before closing the porthole.
Close the portholes and the skylight when navigating or when the yacht is left unattended for a long period.