hydroplane

hydroplane
/ˈhaɪdrəpleɪn; `haɪdrəˌplen/ n
1 light motor boat with a flat bottom, that can travel fast over the surface of the water 机动平底快艇.
2 device on a submarine enabling it to rise or descend （控制潜艇升降的）水平舵.

牛津英汉双解词典