The resultant of bow and stern waves of Model M 8 (L=2 m), the proto-type of the Series II i. c. the Frameline Series is wave-analyzed. As the preliminary step of analysis, careful investigation is carried out with respect to the probable errors which are involved in the well-known procedure of Newman Sharma's longitudinal cut method. First, Newman's truncation formula is found as not valid except y =0, where the elementary wave number k (θ) exactly equals to K ₀=g/V². This fact is of great importance because Newman-Sharma's method has its original basis on the asymptotic expression for the free wave system at the infinite distance ( y =∞). Secondly, the reduplicability of the amplitude function is examined at several Frounde numbers with respect to M 8 for an ideal fluid, where a finite length of “calculated” wave profiles at the center-line cut ( y =0) is adopted. Coincidence is satisfactory except the transverse wave range (θ=0°20°) at hump speeds such as K ₀ L =14 and 10. This suggests that the truncation error is much more important than the effect of finite transverse separation ( y ). Demonstration is also given as to the relation between the magnitude of truncation error and the longitudinal distance ( x ) behind the model, or more exactly, with the radial cut angle Θ. In consideration of these theoretical results, the experiment was carried out not only in the small tank ( b =3. 5 m, Ti. of Tokyo) but also in the large tank ( b =18 m, S. R. I. No. 2 Tank). Four parallel cut lines y / l =O.5, 1.0, 1.5 and 2.0 are adopted, which as a whole give a satisfactory coincidence in the “measured” amplitude function as well as in the “measured” wave resistance. However a remarkable discrepancy is also observed between “measured” and “calculated” wave amplitude, particularly in the smaller range of θ or the transverse wave component, i. e. a serious reduction of amplitude combined with a clear phase-shift toward smaller value of θ. Besides viscosity effects on the stern wave system, some invicid causes like non-linear effects as well as sheltering effects may also be suggested for this discrepancy.