Time- and frequency-domain numerical models are developed to investigate the acoustic performance of metascreen-based coatings for maritime applications. The coating designs are composed of periodic air-filled cavities embedded in a soft elastic medium, which is attached to a hard backing and submerged in water. Numerical results for an acoustic coating with cylindrical cavities are favorably compared with analytical and experimental results from the literature. Frequencies associated with peak sound absorption as a function of the geometric parameters of the cavities and material properties of the host medium are predicted. Variation in the cavity dimensions that modifies the cylindrical-shaped cavities to flat disks or thin needles is modeled. Results reveal that high sound absorption occurs when either the diameter or length of the cavities is reduced. Physical mechanisms governing sound absorption for the various cavity designs are described.