In view of the limitation of the existing ship’s draft measurement methods. A hanging side ship method based on double sonar probe differential scanning is presented to detect the depth of ship’s draft. On the basis of detailed analysis on ship’s curved contour shape

use double sonar differential scanning technology

mathematical model for ship’s draft measurement is set up

design a draught measurement method of ship. Through statistical analysis on 5 groups of draft measurement results

it is found that the maximum relative error is only 4. 87 %

and the precision is higher than the actual engineering error

which verifies the feasibility of the design scheme.