No, not ranting, air vent on the Pilot Boat.
I suppose these are pretty easy in modelling terms - you buy something suitable, drill a hole in the superstructure and glue them in place.
At the front we have mushroom vents and behind, the other sort. According to the model on the stand when I bought the kit, they should face backward. Presumably if forward facing, at speed the air inflow would inflate the cabin !
What I don't understand is how anyone makes a master for these. The stalk is narrower than the gaping mouth. They have to be very hollow too - you can't supply them blind and tell the modeller to drill them out because no known drill could get narrower as the hole turns to head down the shaft.
And before some says "they come out of a mould", yes I know that, but how would you make one by hand ?