This study presents a systematic investigation of bilgewater emulsion characteristics using various in situ analytical methods, while assessing the effect of environmental parameters [e.g., ionic strength, suspended solids (SS), and temperature] on emulsion destabilization. The stabilizing properties of three emulsifiers [Triton X-100, B&B 3100, and sodium dodecyl sulfate SDS)] were evaluated under various conditions over 5 days. Time-course visual observation, relative oil separation, droplet size distribution, and grayscale intensity profiles were used for the physical characterization of the emulsion samples. In particular, the grayscale intensity was found to be a useful technique for the rapid detection of emulsion separation using simple image analysis. Major findings on bilgewater emulsion stability in this study are as follows: (1) emulsion stability decreased with NaCl (ionic strength) addition and temperature increase, resulting in higher oil separation, (2) emulsions stabilized with B&B 3100 (commercial cleaner) were more stable than Triton X-100 and SDS (neat surfactants) at the equivalent critical micelle concentration, and (3) SSs particle size larger than the initial droplet size could promote the formation of larger emulsion droplets, thus increasing oil coalescence as corroborated by visual observation. Overall, this study highlighted a defined set of easy and rapid emulsion analytical methods, which provided significant information regarding bilgewater emulsion stability. These techniques demonstrated to be a rapid solution for the in situ characterization of bilgewater emulsions primarily in offshore locations lacking sophisticated equipment. These methods can be used for further investigation of other cleaning products found on ships and actual bilgewater samples to assist in the appropriate bilgewater treatment and management.