The term pinnace can refer to either a ship’s boat or a larger frigate style vessel. Evelyn uses the term for the latter. In an entry, he describes it as
I marched three English miles toward the packet boat, being a pretty frigate of six guns, which embarked us for England about three in the afternoon.
At our going off, the fort, against which our pinnace anchored saluted my Lord Marshal with twelve great guns, which we answered with three.
The word pinnace, and similar words in many languages came ultimately from the Spanish pinaza c1240, from pino (pine tree), from the wood of which the ships were constructed. The word came into English from the Middle French pinasse. – Wikipedia