Bronze boat porthole opening to 2 cranksets. Around 1940.
These windows are from the same ship. Photo taken the floor (transparent glass).

D 43 D glass 30 cm / 6 cm thick / 12 kg Total Thickness with mannetons 11 cm
9 mounting holes (D 14 mm center distance cm) diameter crossing hull 34 cm (P 1 cm see photo rear view)
Transparent glass in good state. We select the portholes whose glasses are in good condition. They are never split but can have some small scratches due to 40 or 50 years of use.