A GPS APPLICATION AND REAL-TIME ON-THE-FLY APPROACH FOR BATHYMETRIC SURVEYS

 

Every year, the Canadian Coast Guard - Laurentian Region (CCG-LR) conducts bathymetric surveys on a 300 km navigation channel in the St. Lawrence River in order to check its nominal depth. For accurate tidal data, several tide staffs must be installed annually within close proximity of each survey area. CCG-LR currently uses 60 to 70 tide staffs. However, this technology is costly, limited and outdated. The introduction of this technology should improve data quality while having significant impact on data collection cost and effiency.

CCG-RL plans to replace the staffs with GPS On-the-Fly Real Time (Global Positionning System OTF-RT) technology. The OTF-RT approach eliminates the errors associated with water-transfer techniques and some of those associated with the determination of the ships' movement (heave and squat).

During the fall of 1995, CCG-LR tested the potential of the OTF-RT approach in real-operational conditions. The concluding test results prompted Coast Guard - Laurentian Region to adopt OTF-RT technology in conjunction with the Coast Guard DGPS network. This paper presents the vision, the methodology and the preliminary results of the project.