Number + 艘 + 巡逻艇
巡逻艇 (xúnluótǐng) means "patrol boat," a small vessel used by coast guards, navies, or police for maritime surveillance. It is a compound of 巡逻 (to patrol) and 艇 (small boat). This word frequently appears in news reports about search-and-rescue operations.
海上巡逻艇已经出发去搜救了。
Hǎishàng xúnluótǐng yǐjīng chūfā qù sōujiù le.
The maritime patrol boat has already set out for the search and rescue.
两艘巡逻艇在附近海域执行任务。
Liǎng sōu xúnluótǐng zài fùjìn hǎiyù zhíxíng rènwù.
Two patrol boats are carrying out a mission in the nearby waters.
巡逻艇在河面上来回巡视。
Xúnluótǐng zài hémiàn shàng láihuí xúnshì.
The patrol boat is cruising back and forth on the river.