In the early 17th Century, Sweden was at war with Poland. King of Sweden, Gustavus Adolphus, decided to build a ship that was to be a game changer. Very few ships at this time had two decks of guns. He wanted that. He wanted a heavily armed ship that was fast. As you can tell by trying to push your hand through water palm-first or to the side with all fingers following in a line, a narrower ship is going to be easier to move through the water faster.
