Abstract The effect of enamel coating on boat hull drag was studied by using simple boat models of different shapes. The performance of enamel-coated boats was compared with the uncoated boats of the same shape. The effect of speed and normal load on enamel-coated, as well as uncoated boats, was also evaluated. The boat hull drag was measured in a laboratory water tank by a load transducer. In all tests, it was observed that drag force for enamel-coated boats was lower than the same shaped uncoated boats. A maximum reduction in the drag of 15% due to enamel coating was obtained at 2.8 m/s speed and 180 N load. The ratio of drag force/normal load was found to be a function of the Froude number as well as the shape of the boat. The shape of the boat was found to be a significant factor at higher normal load and speed. Due to irregular boat shapes used in this study, the benefits of coating were reduced by early boundary layer separation. Therefore it was revealed that streamlined boats may show more significant reduction in the drag due to enamel coating.