several boats; a few vessels
Used as a noun to refer to a small number of boats or ships. The counter 隻 is specifically for vessels.
Several fishing boats were anchored in the harbor.
A few ships can be seen offshore.
数台 is used for counting vehicles or machines, while 数隻 is specifically for boats and ships.
数機 is used for counting aircraft, whereas 数隻 is for vessels.
Compound of 数 (several) and 隻 (counter for boats/ships). The reading すうせき follows standard on'yomi.