Prepare spud plate and wireline to check water depth 準備測深板和鋼絲繩測量水深
Chart datum : the level to which soundings or tide heights are referenced 海圖基準面:測量水深或潮水高度的基礎高度。
Items found nearby a lead - - used for depth sounding , a ring for aftaching sails to a mast , and copper nails - - could have belonged to other ships 在附近找到的一些小物件? ?用于測量水深的測深錘,把帆系到桅桿上的環圈和銅釘? ?可能屬于其它船只。
Because the elevation data we have acquired through gps is too variable to satisfy the mapping accuracy requirement the elevation value is solved by the water lever observation in the hydrology station and datum horizon correction of sounding observation 由于gps的rtk模式測量所獲取的高程精度不能滿足測圖精度要求,因此其高程值是通過測量水深值、結合其統一到基準面的改正數、根據相關水文部門各水位站提供的水位觀測資料綜合計算獲得。