The phrase "active vessels" is correct and usable in written English.
It can be used in contexts related to biology, medicine, or any field discussing circulation or transportation systems.
Example: "The study focused on the role of active vessels in the delivery of nutrients to tissues."
Alternatives: "functioning vessels" or "operational vessels".
For example, there have been considerable reductions in the number of active vessels and entities holding quota share in the Alaska Halibut and Sablefish and the Mid-Atlantic Surfclam and Ocean Quahog catch share programs.
Increases in day rates in the Gulf of Mexico have been particularly strong, and all of the company's active vessels in the Gulf are working under term contracts.
Financial problems forced the French Navy to reduce its battleship force to four active vessels.
The NWHI bottomfish fishery is a limited entry fishery, with eight active vessels, which are restricted to 60 feet in length.
Table 4 — Norway — Number of active vessels.
The average of the average best two of four years' mobile catch histories for active vessels in the same tonnage class.
Midshipmen at the US Naval Academy study a core curriculum plus 21 major fields of study, a wide variety of elective courses and advanced study and research opportunities, as well as a required "surface cruise" with an active vessel during the summer.
This corresponds to the more angiogenically active vessel front (Fig. 4S).
The total employment in 2015 was estimated at 1 728 jobs, corresponding to 608 FTEs with an average of 0.5 FTE per active vessel.
The total employment in 2014 was estimated at 1 517 jobs, corresponding to 532 Full-time-equivalents (FTEs) with an average of 0.5 FTE per active vessel.
Total employment in 2016 was estimated at 1 603 jobs, corresponding to 580 FTEs with an average of 0.5 FTE per active vessel.
