Quote Originally Posted by lw395 View Post
There is drag and there is inertia.

It takes more force to start moving a paddle through the water than to keep it moving at a steady speed.
That extra force is due to the inertia of the water.
Once the paddle is moving so is the water to some extent so the relative velocity between the water & the paddle is reduced, the u squared term in the drag equation decreases & hence the force decreases.

I still suggest that the hydrodynamic drag of a chum is trivial with my (admittedly simple) analysis & you have not countered it with anything convincing other than dubious use of the term inertia.