SHIP HANDLING in Following Seas

Nice video useful information for mariner.

Hello how on earth do i Read the Diagram of Encounter waves,,, Explain

Captain: Helmsman, adjust the encounterwave period, so that is does not coincide with one half of the natural rolling period of the ship!
Helmans: Aye Sir (prcoeeds to adjust the encounterwave period)

Increase size and length of Bilge Keel Plate.

To stop the parametric rolling, you could also increase GM thus speeding up the roll period. So that the right way of thinking about it?

So basically in a following sea, slow down, alter course if possible

How does a sailing vessels deep keel and ballast affect these formulas?