 shallow water wave resist shallow water wave resist gener charact experiment deal shallow water ship resist state --at low veloc resist shallow water greater deep water speed excess appreci vari type vessel speed increas excess resist increas maximum critic veloc diminish increas speed resist shallow water ultim remain deep water speed maximum pronounc shallow water detail refer refer standard treatis quotat regard critic veloc maximum appear speed trochoid wave travel speed water depth time long vessel time suppos speed maximum increas resist wave translat hold water depth greater depth speed wave translat rapidli greater speed maximum increas resist analysi data weitbrecht express conclus state depth water critic veloc critic veloc vari squar root correspond depth 