‘Apply Refraction’ portion of this section iii iv Chapter 1 Systems Preparation Maintenance 1 1.1 Annual Systems Preparation 1 1.1.1 Hydrographic Systems Readiness Review 1 1.2 Periodic Quality Assurance 2 1.3 Basic Methods and Documentation 2 1.3.1 Hydrographic Systems Inventory 3 1.4 Vessels 4 ...