YOU SAID:

I went to see a boat sailing away in the horizon.

INTO JAPANESE

私は地平線に船が出て行くのを見に行きました。

BACK INTO ENGLISH

I went to see the boat leaving the horizon.

INTO JAPANESE

ボートが地平線を離れるところを見に行きました。

BACK INTO ENGLISH

I went to see the boat leaving the horizon.