Boat (10) comprising a steering and propelling unit comprising at least one driving shaft (11, 11′) passing in an opening of the transom (12) for transmitting the motion from a motor to at least one propeller (21, 21′), at least one steering (14) provided at the top with at least one rotation pin (13), and a through-hull support (100) able to be associated with the opening and equipped with a plate portion (101) able to be fixed on the outside to the hull (12) of the boat (10) and with a through-hull tubular portion (102) for support of the at least one driving shaft (11, 11′), in which the through-hull support (100) also comprises at least one bush (103) passing through the plate portion (101) to support, in a rotary manner, the pin (13) bearing the steering (14) and in which the wall (12) of the hull where the passage opening of the at least one driving shaft (11, 11′) is formed is inclined from the top to the bottom in the direction of the stem of the boat (10).