Below is my new upload: OD type submarine chaser (this particular is ORP Śmiały). 12 such boats were obtained by Polish Navy from the Soviet Union in the 1946 and they served until 1960.
I must admit, that I'm not fully content with this drawing. Besides windows on the superstructure (but I don't think anything could be done with that), my main problem is with a gun - it's a standard 37mm gun, but the standard one (from the template) is obviously way too big, and I'm tempted to make my own.
Also, a note about mast - actually it's a thin mast (forward) and parallel antenna (?), several (perhaps 10) centimeters behind it, connected to mast in several places.
P.S. WhyMe - Thank You very much.
EDIT: There is some confusion in Polish sources about proper project number (Pr.200) and it's type name - which for the Pr.200 is OD (OD-200) but our sources use name MO-D-3 instead (which fits rather ASW conversions of D-3 torpedo motor boat)