Here's how:

1) Place flotation along the entire length of the pennant so it can't sink below the ball. (I use closed-cell pipe insulation from Home Depot and tape it every 12-18").

2) Use a mooring ball that's a cylinder shape, or if it's ball-shaped -- size it so the weight of the chain sinks it at least halfway (this lets the pennant pull over the top rather than under).