Off the port, a lighter was transferring cargo from the large freighter.
Standard kanji spelling.
Variant spelling without okurigana.
Compound of 瀬取り (sedori, 'unloading cargo from a ship at anchor') + 船 (fune, 'boat'). The exact historical derivation of 瀬取り is uncertain, but it likely relates to the maritime practice of transferring goods in shallow waters or near a sandbar (瀬).