The original postcard arrived from France:

There are a plenty of interesting details to be found:

a)
The windowframes are whiter than the hullcolour - so the hull is not a bright white!
b)
What is the structure aft the window for?
c)
Could this be a metal block above the window?

a)
The mushroom vents are with a dark top head - black? DARK blue?
b) The netting is beginning in a rail in the lower Edge of the "grill deck"'s framing, turning INSIDE the second rail and ending in and out a ropeon 2/3s of the stanchions hight. As the sailor can press down the netting it has to be a rope.

a)
The netting isn't interrupted for the gangway - but the railing is.
b)
The handrails are fixed and the A-rods are from the very same shade of colour as the mushroom vents' tops.
c)
The mushroom vent in the "grill deck" is white topped.
a)
The pair of "vents" at the hull's top are bronze(?).
b)
There seems to be a pipe INSIDE the "tunnel" in the starboard side.
c)
the shape of the grill is interesting and complex.
So there is a plenty to discuss here.
@Waldemar have you got any helpfull ideas?