A Fundamental Study on Measurement of Hull Roughness

Abstract

In this study, an investigation on the hull roughness measurement of a new ship, a 160m class car ferry, was performed. The hull roughness measurement was conducted in the ferry's pre-coated state before launching. For measurement, the TQC manual and ITTC recommendations were considered, and measurements were made in a total of 230 zones below waterline of the ship. Accordingly, the average hull roughness of the car ferry was 81 , which is relatively low compared to 150 , the hull roughness of a new ship proposed by the ITTC. In addition, the measurement uncertainty was calculated using the ISO guidelines, and the effect of the number of zones on the hull roughness measurement was examined. Using the measured average hull roughness, we estimated the resistance performance at the design speed of the ship. Accordingly, it was confirmed that the total resistance of the new ship was reduced by approximately 2% owing to a decrease in its frictional resistance increase.

Numerical investigation on the effect of homogenous roughness due to biofouling on ship friction resistance

“…Because frictional drag accounts for roughly 90% of total drag, the increase in frictional drag value due to increased surface roughness follows the same pattern as the increase in total drag. The frictional drag value obtained by CFD simulation of the two models under smooth surface conditions has a good agreement with the ITTC empirical equation [25], with a difference of less than 2%. Furthermore, utilizing the empirical approach of the Granville similarity [26] to estimate CF on rough surfaces provides values that are consistent with the CFD simulation results.…”

“…values taken from a numerical study [23], namely 81.25 𝜇𝑚, 325.00 𝜇𝑚, and 568.75 𝜇𝑚, representing realistically fouled hull [15]. An experimental study investigated the measurement techniques of hull roughness on a 160 m new class car ferry, where the actual average hull roughness was found to have a value of 81 𝜇𝑚, far beneath the hull roughness of a new ship proposed by ITTC at 150 𝜇𝑚 [25]. Therefore, the use of 81.25 𝜇𝑚 as one of the roughness conditions gained more confidence in representing actual roughness on ships.…”

“…While the ship itself was set as a wall function. The overall computational domain size was determined according to the ITTC [25], with L as the overall length of the ship (see Figure 2). The velocity inlet was measured 1.5L from the fore point of the model, the pressure outlet was set 3L after the aft point of the model, the bottom was set 1.5L from the base of the model and the side wall was measured at 2L from the outer hull of the ship.…”

A comprehensive review on the prediction of ship energy consumption and pollution gas emissions

“…Ship energy consumption and emission are not only related to the ship parameters, but also related to navigational environment (Fan et al, 2021), sailing state (Lu et al, 2015), ship loading (Tran, 2020), hull fouling (Adland et al, 2018), applied antifouling coating (Farkas et al, 2021;Seok and Park, 2020), etc. Therefore, the related data are diverse and huge (Lensu and Goerlandt, 2019;Wang et al, 2016a), and the data types are complex and diverse (Zhu et al, 2021).…”