Stuck on a sentence

[tmho160]

Hello, i'm sorta stuck on a sentance in a book i'm looking at. It's a childrens book yet i don't quite understand what it means. I sorta know what each individual word means but that ain't helping and my mum can't seem to explain it to me. It's 可海水卻很重, 要讓他挪動一下, 還非得大風不可呢. It's the 還非得大風不可呢 which i don't quite understand. Can someone explain it to me please. Thanx.

[skylee]

But the sea water is heavy. To make him move a bit, it won't be possible without a strong wind / unless there is a strong wind.

非 XX 不可 - something is not possible unless there is XX / unless XX happens

[RobAnt]

To make him move a bit, it won't be possible without a strong wind

So, to clarify, is this someone swimming? Or is it maybe a boat or other vessel, where the object has been given a masculine attribute?

In English we might say "she was listing" refering to a ship, for instance, giving the vessel a feminine attribute - it could also apply to other vehicles - such as cars or, indeed, any object the author wishes to characterise or humanise.

I don't understand any of it, I can't read Chinese.