© 2020 IEEE.The Global Positioning System (GPS) and integrated sonar systems are widely used for obtaining bathymetric data. While the water vehicle coordinates can be provided with real-time kinematic (RTK) GPS observations instantaneously, depth information can be obtained through integrated sonar systems. The oscillation caused by factors such as wind and wave affects the position accuracy of bathymetric data. In this study, performance analysis was performed by using an inertial navigation system (INS) together with more than one GPS receiver to test the angular changes caused by the oscillation of the boat, in case of bathymetric operation with unmanned water vehicle. While there is a weak correlation between angular changes obtained from the RTK GPS method and INS in case of low boat oscillation, high correlation of approximately 99% in pitch and roll angles has been found if oscillation increases.