A novel indicator for ship hull and propeller performance: Examples from two shipping segments
Artikel i vetenskaplig tidskrift, 2020

Ship hulls and propellers suffer from both mechanical defects and marine growth, which increase surface roughness and thus lead to significant power/speed penalties. A recent standard, ISO 19030:2016, aimed at establishing a transparent and accurate method to compare a vessel’s performance to itself over time. However, the standard performance value, percentage speed difference Vdiff, is both vessel-specific and sensitive to operation point, most importantly vessel speed. The current paper thus proposes a new performance indicator, based on the concept of equivalent sand-grain roughness height k_s, which would enable comparisons between vessels, increased accuracy for comparison of a vessel to itself over time, and calculation of penalties under operating conditions differing from past data (e.g. slow steaming). Sand-grain height k_s is determined iteratively, through modelling roughness penalties on propulsive power (Granville’s similarity law scaling), comparing modelled and measured penalties, and stopping the iterative process at a given tolerance on power penalty. This new performance indicator is applied to onboard-collected data from a Panamax tanker and two Roll-on/Roll-off sister vessels, yielding qualitative agreement with hull condition reported from diving inspections. Comparative advantages and limitations of k_s are discussed in relation to the ISO 19030 performance value.

In-water hull cleaning

ISO 19030

Fouling-control coatings

Hull roughness

Energy efficiency

Hull biofouling

Författare

Dinis Oliveira

Chalmers, Mekanik och maritima vetenskaper, Maritima studier, Maritim miljövetenskap

Lena Granhag

Chalmers, Mekanik och maritima vetenskaper, Maritima studier, Maritim miljövetenskap

Lars Larsson

Chalmers, Mekanik och maritima vetenskaper, Marin teknik

Ocean Engineering

0029-8018 (ISSN)

Vol. 205 107229

Completing management options in the Baltic Sea Region to reduce risk of invasive species introduction by shipping COMPLETE

Interreg-BSR, 2017-10-01 -- 2020-09-30.

Ämneskategorier

Energiteknik

Tillförlitlighets- och kvalitetsteknik

Strömningsmekanik och akustik

DOI

10.1016/j.oceaneng.2020.107229

Mer information

Senast uppdaterat

2020-05-20