Bollard Pull Standard
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MARI N P.O. Box 28 6700 AA Wageningen The Netherlands T +31 317 49 39 11 F +31 317 49 32 45 E [email protected] I www.marin.nl V. 2014/05/26_T&M Joint Industry Project Bollard Pull Standard Background The bollard pull of a tug, offshore supply vessel or fishing boat is an important parameter from a contractual and commercial point of view. The bollard pull is defined as the mean exerted force at zero speed for a certain period of time. For the determination of the bollard pull the ITS2002 Bollard Pull Trial Code is currently the standard [1]. In this Code are described the bollard pull trial conduct, the criteria and the corrections on the measured bollard pull for non-ideal conditions. The completeness and corrections applied in this Code, however, are disputable. A first exploration with systematic model tests to determine the corrections of varying water depth and distance to the quay on the measured bollard pull was conducted at MARIN in November 2013 [2]. The measured corrections were compared with the current Code. Corrections for tow line length and water depth according to the Code can be as high as 14%. The model tests resulted in significantly lower corrections for water depth and tow line length as illustrated in the figure below. In the ITS2002 Bollard Pull Trial Code is also stated that the aim is to start a discussion regarding bollard pull with an internationally accepted bollard pull as the ultimate goal. However, this has never resulted in a final standard. Currently, the bollard pull determination is interpreted differently even by Classification Societies. With the Bollard Pull Standard JIP the relevant parameters that can be of influence on the bollard pull will be investigated. The aim is to develop an improved method for the bollard pull trial and bollard pull determination which is generally accepted by all parties involved. Black lines: ITS2002 publication and the coloured lines: current model tests. Objectives Discuss with a broad spectrum of stakeholders in the towing industry their experiences and issues during bollard pull trials and determination. Obtain insight into the relevance of parameters based on their influence on the magnitude of the measured bollard pull. For the relevant parameters determine acceptable correction methods for the measured bollard pull. Develop an improved and generally accepted bollard pull measurement standard for the towing industry. 0.98 1 1.02 1.04 1.06 1.08 1.1 1.12 1.14 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 correction factor k [‐] d/dmin [‐] k based on bollard pull 5 minutes full scale at 560 RPM L/Lt=1.0 L/Lt=0.8 L/Lt=0.6 L/Lt=0.4 L/Lt=0.40 L/Lt=0.50 L/Lt=0.60 L/Lt=0.80 L/Lt=1.00 L/Lt=1.50 0.98 1 1.02 1.04 1.06 1.08 1.1 1.12 1.14 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 correction factor k [‐] d/dmin [‐] k based on bollard pull 10 minutes full scale at 560 RPM L/Lt=1.0 L/Lt=0.8 L/Lt=0.6 L/Lt=0.4 L/Lt=0.40 L/Lt=0.50 L/Lt=0.60 L/Lt=0.80 L/Lt=1.00 L/Lt=1.50
Transcript of Bollard Pull Standard
M A R I N P.O. Box 28
6700 AA Wageningen The Netherlands
T +31 317 49 39 11 F +31 317 49 32 45
E [email protected] I www.marin.nl
V. 20
14/0
5/26
_T&M
Joint Industry Project
Bollard Pull Standard Background
The bollard pull of a tug, offshore supply vessel or fishing boat is an important parameter from a contractual and commercial point of view. The bollard pull is defined as the mean exerted force at zero speed for a certain period of time. For the determination of the bollard pull the ITS2002 Bollard Pull Trial Code is currently the standard [1]. In this Code are described the bollard pull trial conduct, the criteria and the corrections on the measured bollard pull for non-ideal conditions. The completeness and corrections applied in this Code, however, are disputable. A first exploration with systematic model tests to determine the corrections of varying water depth and distance to the quay on the measured bollard pull was conducted at MARIN in November 2013 [2]. The measured corrections were compared with the current Code. Corrections for tow line length and water depth according to the Code can be as high as 14%. The model tests resulted in significantly lower corrections for water depth and tow line length as illustrated in the figure below. In the ITS2002 Bollard Pull Trial Code is also stated that the aim is to start a discussion regarding bollard pull with an internationally accepted bollard pull as the ultimate goal. However, this has never resulted in a final standard. Currently, the bollard pull determination is interpreted differently even by Classification Societies. With the Bollard Pull Standard JIP the relevant parameters that can be of influence on the bollard pull will be investigated. The aim is to develop an improved method for the bollard pull trial and bollard pull determination which is generally accepted by all parties involved.
Black lines: ITS2002 publication and the coloured lines: current model tests.
Objectives
Discuss with a broad spectrum of stakeholders in the towing industry their experiences and issues during bollard pull trials and determination.
Obtain insight into the relevance of parameters based on their influence on the magnitude of the measured bollard pull.
For the relevant parameters determine acceptable correction methods for the measured bollard pull.
Develop an improved and generally accepted bollard pull measurement standard for the towing industry.
0.98
1
1.02
1.04
1.06
1.08
1.1
1.12
1.14
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
correction factor k [‐]
d/dmin [‐]
k based on bollard pull 5 minutes full scale at 560 RPM
L/Lt=1.0
L/Lt=0.8
L/Lt=0.6
L/Lt=0.4
L/Lt=0.40
L/Lt=0.50
L/Lt=0.60
L/Lt=0.80
L/Lt=1.00
L/Lt=1.50
0.98
1
1.02
1.04
1.06
1.08
1.1
1.12
1.14
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
correction factor k [‐]
d/dmin [‐]
k based on bollard pull 10 minutes full scale at 560 RPM
L/Lt=1.0
L/Lt=0.8
L/Lt=0.6
L/Lt=0.4
L/Lt=0.40
L/Lt=0.50
L/Lt=0.60
L/Lt=0.80
L/Lt=1.00
L/Lt=1.50
To achieve these objectives the co-operation of stakeholders in the towing industry is needed. They can provide the necessary experience, facilitate the full scale trials and provide feedback. Their input is an important guidance for the development of a generally accepted standard.
Scope of work
The following main activities are distinguished: 1. Review of existing methods and Regulations. 2. Review of existing bollard pull locations and location bound
parameters. 3. Enumerate and select all relevant parameters. 4. Develop correction methods for the relevant parameters. 5. Select the necessary instrumentation and set-up. 6. Develop a report standard. 7. Draw up a complete code of conduct. For the development of the correction methods, applied systematic model tests, full scale trials and Computational Fluid Dynamics calculations will be applied. The method used will depend on the parameter to be investigated and the measurement practicality. Deliverables
The project will deliver specifications for the instrumentation and bollard pull conduct standard. The corrections on the measured bollard pull that are to be applied for the relevant parameters will be set out in a report.
Organisation
MARIN will lead this JIP in close co-operation with their participants. Design offices, ship yards, shipping companies, suppliers and classification societies are all invited to join this JIP. Participant Meetings will be held every 6 months as part of the vessel operator forum.
Schedule
The running time of the Bollard Pull Standard JIP is 1.5 years. The JIP is scheduled to start in September 2014 and to finish in February 2016.
References
[1] Bollard Pull Trial Code proposal, ITS 2002, Hannu Jukola and Anders Skogman, Steerprop Ltd, Finland.
[2] MIIP pilot project: Bollard Pull Standard, Model tests to measure
effect of water depth and tow line length on bollard pull Trial Code, MARIN report No. 26756-1-TM, January 2014.
Iskes’ tug “Brent” on bollard pull trial
Model tests at MARIN December 2013
For more information please contact the department Trials & Monitoring; Alfons Bruning Henk van den Boom T +31 317 49 33 65 +31 317 49 33 53 E [email protected] [email protected]
