A hull-cleaning robot sticks to the surface of a vessel and moves for efficient cleaning. Precise path planning and tracking using thecurrent position is crucial. Many robots rely on the INS algorithm, but errors accumulate. To fix this, GPS, sonar, and USBL are used,though with limitations. Selecting suitable sensors for the surface operation and accurate positioning algorithm are vital. In this study,we developed a robot position estimation algorithm using the structure of a ship. Problems that arise when expanding the 2D positionestimation algorithm used in existing wall structures to 3D were evaluated and methods for solving them were proposed. In addition,we aimed to improve performance by deriving singularities that exist in the robot path and proposing an error correction algorithm basedon the singularities.