During the ship battle tutorial you will be tasked with ramming another ship once it's immobilised. You will want to hit the side of it directly in the centre while holding "W" to initiate ram speed. If you miss out on this spot you can do it to any other enemy ship that can be boarded.
Solution sourced from Dr Zoidstein:
https://www.trueachievements.com/gamer/Dr+Zoidstein