As I have been looking at jachts, it is worth looking at a good example of a moderate-sized, three-masted jacht, the Heemskerck. This was the ship in which Abel Tasman did his exploration. He was accompanied by a fluit, the Zeehaan.
The Heemskerck was built in 1638, with dimensions: 106ft x 24ft x 9ft (Amsterdam feet). Without being able to consult Ab Hoving's book, I would guess the armament to have been 14-18 guns.
Artitec, the fine model makers have a picture of their Heemskerck model:
