Harbor protection systems detect unauthorized harbor entry by intruders such as divers, mini-submarines, and small boats. These systems typically consists of a sensor network array to detect harbor entry, a messaging system to communicate status, and a response system to react to any perceived threat. This system falls under the general problem of detecting a moving target through an array of stationary sensors. If the sensor performance is misunderstood, overall system performance can be erroneous. In particular, the assumption of independence with respect to intra-sensor detection opportunities is often incorrect, resulting in overly optimistic performance estimates, which can be attributed to correlated data. We define strongly correlated data, and using this assumption, provide a result which relates the probability of first detection with the maximum probability of detection.