The author herewith proposes the new system of hydro-static calculation for the basic design of merchant ships as shown in Tables 1, 2 and 3.This system is very convenient to use at any time and anywhere when desired.The key points of this system are as follows : -(1) The offsets of the water planes are non-dimensional, being easily obtainable by the percent scale as shown in Fig. 2(2) The simplification of the calculation with the use of 5 constants, i. e., λ, β, δ, κ and κδ which are led from L, B and d of the ship.(3) The simplification of the integral of the water plane with the application of the 5·8·-1 rule and the 3·10·-1 moment rule. Only half of the numbers of the water planes are necessary : for the calculation as compared with the application of the Simpson's 1 st rule.(4) The standardization of the units in the calculation.