Safety and security in marine environments is an emerging application area of low-power wireless sensor networks. Yet, these environments pose big challenges to network reliability. The IEEE802.15.4-TSCH protocol has been extensively regarded as a reliable low-power wireless sensor network solution. It requires, though, an external scheduling mechanism in place to allocate connections to specific timeslots and transmission channels. In changing environments, rescheduling is often required to keep up with network performance. To ease the schedule selection process, we propose a schedule assessment method given a certain topology. The method combines the schedule and topology into an interference graph and uses the network density metric to rate the schedule. Moreover, it pinpoints the connections and pair of nodes that should be rescheduled to improve schedule efficiency. The experiments and initial results have shown high accuracy on rating schedules as well as on selecting connections for rescheduling. The results have also indicated directions of improvement of the method.