It's a bit like if you're pushing a boat through a river and measuring something about the surface - you don't want to measure the ripples from the boat.

这就有点儿像你将一艘船从河的这边推到另一边，并测量河面上的某些东西，但你不希望连同船儿泛起的涟漪也一并测量出来。

youdao

It has been successfully used in measuring angular displacement within paddle of racing boat.

将其用于赛艇角位移测量，收到较好的效果。

youdao

On any boat you are continuously measuring and judging the environment, and even down in a hold, working on a shit pump, some part of you is aware of the wind shift.

FORBES: The Disaster Diaries Book Review - From Sailor To Survivalist