Sentence:  With these completed and ice gone from the St. Peter's River ( present-day Minnesota river ) their 250 bushels of wheat , 100 bushels of oats and barley and 30 bushels of peas and some chickens were loaded onto the <WSD>flat-bottomed</WSD> boats and rowed up the river to Big Stone Lake , across into Lake Traverse , and down the Red . 
Meaning of the word marked with <WSD> tags:  having a flat bottom