the ship is here on top just like this? So, in the propeller disc if I take a section, the ship is
somewhere here, there is nothing below- can you understand that section?- there is a
restriction here, just see this little part, we will, when we come to wake we will see it in
greater detail, which we will do, but right now to understand the propeller, how it works
properly; see, there is a ship here, a ship here, but below there is nothing, so you can well
understand thus, water that is coming past ship is not having a constant velocity all over the
propeller disc- can you understand this, yes or no? Since it is not having a constant velocity
across the propeller disc, the propeller cannot behave exactly similarly as if there was a
constant velocity that is, each section will behave slightly differently with water than the
other section because the speed is varying- can you understand that? So, when you say VA is
constant, what are you saying, are you saying that each velocity is constant on each propeller
disc, each point is it constant, or are you saying overall velocity VA, I am giving, what you
are saying? When you say speed of advance VA it means you have made some sort of
averaging this over this whole disc and saying VA, it does not mean VA is same at all points
on propeller disc- is that clear? So, when we are saying VA, we are also averaging