flat-fish, plaice, flounder
scow, barge, lighter
flat-bottomed fishing boat, fishing smack
flatbed truck, flatbed trailer
Рыбаки держали плоскодонку у берега.
The fishermen kept the flat-bottomed boat by the shore.
Для рыбалки в камышах нужна плоскодонная лодка.
You need a flat-bottomed boat for fishing among the reeds.