Typically a deisel motor like the MD2030 should be run around 75% of maximum rpm. In that case max is 3600 rpm and 75% would be 2700 rpm. The original prop (16 x 12) did not allow full rpm and hull speed was attained at around 2000/2100 rpm. As a result motoring at 5 knots had the rpm down at 1800 rpm or less. Not ideal.