Convex optimisation model for ship speed profile: Optimisation under fixed schedule

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2021-07-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
23
Series
Journal of Marine Science and Engineering, Volume 9, issue 7
Abstract
We present a novel convex optimisation model for ship speed profile optimisation under varying environmental conditions, with a fixed schedule for the journey. To demonstrate the efficacy of the proposed method, a combined speed profile optimisation model was developed that employed an existing dynamic programming approach, along the novel convex optimisation model. The proposed model was tested with 5 different ships for 20 journeys from Houston, Texas to London Gateway, with differing environmental conditions, which were retrieved from actual weather forecasts. As a result, it was shown that the combined model with both dynamic programming and convex optimisation was approximately 22% more effective in developing a fuel saving speed profile compared to dynamic programming alone. Overall, average fuel savings for the studied voyages with speed profile optimisation was approximately 1.1% compared to operation with a fixed speed and 3.5% for voyages where significant variance in environmental conditions was present. Speed profile optimisation was found to be especially beneficial in cases where detrimental environmental conditions could be avoided with minor speed adjustments. Relaxation of the fixed schedule constraint likely leads to larger savings but makes comparison virtually impossible as a lower speed leads to lower propulsion energy needed.
Description
Funding Information: Funding: This research was funded by the Aalto University School of Engineering doctoral school. Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Keywords
Convex optimisation, Dijkstra’s algorithm, Speed optimisation, Voyage optimisation
Other note
Citation
Huotari, J, Manderbacka, T, Ritari, A & Tammi, K 2021, ' Convex optimisation model for ship speed profile : Optimisation under fixed schedule ', Journal of Marine Science and Engineering, vol. 9, no. 7, 730 . https://doi.org/10.3390/jmse9070730