Year: 2015 Language: english Author: Eide, Egill Genre: Research papers Publisher: NTNU-Trondheim Edition: First ISBN: N/A Format: PDF Quality: eBook Pages count: 104 Description: According to the author, the speed-power performance of ships is usually predicted for an idealized trial condition, with a clean hull and negligible waves and wind. When the ship is in normal operation, with some hull fouling as well as waves and wind, the power required to reach a certain speed is higher than the speed originally predicted and measured on the delivery sea trial. This increase is usually expressed as a sea margin, which is normally added to the power. A typical value for the sea margin is usually in the range 15-20%. The value of the sea margin is set according to tradition and some practical experience, but it is not normally based on proper calculations utilizing knowledge about the actual ship, her condition, and her operational profile. There might be other margins defined as well, and names might vary, like service margin, engine operational margin and light running margin. ITTC has a recommended procedure describing some of this. This research, among other issues, gives a thorough review of operational margins, based both on literature and on information from towing tank(s) and ship owner(s). The review discusses different types of margins and how they are decided. Moreover, it gives a thorough review of available methods to compute sea margin (like methods to compute added resistance and speed loss due to waves, and how such methods can be used to compute the sea margin), and service margin, and thus, it is a survey on methods to account for hull and propeller fouling. Furthermore, it discusses the different operational margins in use and mentioned in the literature, and on that basis, it offers clear definitions of the margins used in this particular master thesis. Additional info: Please, check out my other releases!!!
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Calculation of Service & Sea Margins - Eide, Egill - 2015.pdf
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Calculation of Service & Sea Margins
Language: english
Author: Eide, Egill
Genre: Research papers
Publisher: NTNU-Trondheim
Edition: First
ISBN: N/A
Format: PDF
Quality: eBook
Pages count: 104
Description:
According to the author, the speed-power performance of ships is usually predicted for an idealized trial condition, with a clean hull and negligible waves and wind. When the ship is in normal operation, with some hull fouling as well as waves and wind, the power required to reach a certain speed is higher than the speed originally predicted and measured on the delivery sea trial. This increase is usually expressed as a sea margin, which is normally added to the power.
A typical value for the sea margin is usually in the range 15-20%. The value of the sea margin is set according to tradition and some practical experience, but it is not normally based on proper calculations utilizing knowledge about the actual ship, her condition, and her operational profile. There might be other margins defined as well, and names might vary, like service margin, engine operational margin and light running margin. ITTC has a recommended procedure describing some of this.
This research, among other issues, gives a thorough review of operational margins, based both on literature and on information from towing tank(s) and ship owner(s). The review discusses different types of margins and how they are decided.
Moreover, it gives a thorough review of available methods to compute sea margin (like methods to compute added resistance and speed loss due to waves, and how such methods can be used to compute the sea margin), and service margin, and thus, it is a survey on methods to account for hull and propeller fouling.
Furthermore, it discusses the different operational margins in use and mentioned in the literature, and on that basis, it offers clear definitions of the margins used in this particular master thesis.
Additional info: Please, check out my other releases!!!
Contents
Screenshots
Calculation of Service & Sea Margins - Eide, Egill - 2015.pdf
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