DI-010_REV_1_ABS_ICE_CLASS_ANALYSIS.pdf
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- NPS ISRO Ranger IV Vessel
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- 140PS125R0009
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This document is a DI-010 ABS Ice Class Analysis report for the preliminary/contract design of Motor Vessel Ranger IV, submitted by Loch Harbour Group under Contract No. 6913G623P800007. The report analyzes the appropriate ice class for the vessel based on historical ice data from the U.S. National Ice Center, covering the period from 2018 to 2023. After reviewing ice charts and concentrations for April 1st and April 30th, the design team recommends an ABS Ice Class IE, which is suitable for navigating in extremely light ice conditions with potential icebreaker assistance.
The recommendation is based on several factors, including the vessel's planned operation from mid-April when ice is thawing, the United States Coast Guard's ability to clear the Houghton Channel, and the typically thin first-year ice (approximately 30mm) along the Isle Royale docks. To accommodate potential ice encounters, the vessel's bow will be reinforced with higher-grade steel. The report emphasizes that a higher ice classification would require significant weight and equipment modifications, which would be an over-design for the vessel's mission and operational profile.
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DI-010 Ice Class Analysis Contract 6913G623P800007
Preliminary/Contract Design of Motor Vessel Ranger IV
Ice Class Analysis
Submitted by:
Loch Harbour Group
3060 Williams Drive, Suite 510
Fairfax, Virginia 22031
Contract No.: 6913G623P800007
CLIN-00100
DI-010 ABS Ice Class Analysis Revision 1
Submittal Date: July 24, 2024
DISTRIBUTION Statement C: Distribution authorized to the U.S. Government agencies and their Contractors. Other requests for this document shall be referred to the US Department of Transportation Volpe Center.
DATA RIGHTS: This report, drawing, design, concept, and specification are the intellectual property of Loch Harbour
Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C and contain information which is proprietary. The rights defined below are reserved by Loch Harbour Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C.
The United States Government’s rights to use, modify, reproduce, release, perform, display, or disclose these technical data are unrestricted. Any reproduction of technical data or portions thereof marked with this legend must also reproduce the markings.
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
ACRONYMS AND ABBREVIATIONS
REVISION TABLE
EXECUTIVE SUMMARY
A. TYPICAL ICE CONDITIONS IN THE AREA OF OPERATION
B. ABS ICE CLASS SELECTION FOR OPERATING PROFILE
C. ICE CLASS FOR RANGER IV
D. ATTACHMENTS
• Attachment A – Ice Charts – April 1st (2018-2023)
• Attachment B – Ice Charts – April 30th (2018-2023)
E. REFERENCES
LIST OF TABLES
Table 1: Table showing Ice concentration on April 1st Table 2: Table showing Ice concentration on April 30th Table 3: Guide for selection of ice-class (ABS MVR 2024 Part 6-1-4/3.1)
LIST OF FIGURES
Figure 1: "Egg" Chart as mandated by WMO Figure 2: An example on interpretation of ice chart "Egg"
ACRONYMS AND ABBREVIATIONS
ACRONYM DESCRIPTION
DRL Data Requirements List
SOW Statement of Work
DI Data Item
WMO World Meteorological Organization
ABS American Bureau of Shipping
REVISION TABLE
REVISION DESCRIPTION DATE AUTHOR
0 Initial submission 06-19-2024 LHG
1 Updated to address Government comments 07-24-2024 LHG
EXECUTIVE SUMMARY
This document is submitted by Loch Harbour Group, 3060 Williams Drive, Suite 510, Fairfax, Virginia 22031, to satisfy CLIN 00100 DI-010 ABS Ice Class Analysis, of Contract No.
6913G623P800007.
The purpose of this report is to document the selection of applicable ABS Ice Class for the operating profile, the typical winter ice conditions at all docking locations, and a description of how the ice condition data was used to determine ice class.
The ice class for this vessel will be designed to be ABS Ice Class IE in accordance with ABS
Marine Vessel Rules (MVR) 2024.
Government REVIEW and COMMENT of this report is REQUIRED.
A. TYPICAL ICE CONDITIONS IN THE AREA OF OPERATION
Ice data was taken from the U.S National Ice Center (USNIC) website. Archived data from the previous 5 years was studied and suitable assumptions were made when it comes to interpretation of the ice egg charts. The data is exclusively collected for an area in which RANGER IV will operate. Refer Table 1 & Table 2 for the summarized data.
Sea ice charts incorporate standard parameters found in ‘egg’ symbols, named after their oval shape. Below is a sample image showing the egg code and various stages/ concentrations of ice.
Figure 1: "Egg" Chart as mandated by WMO.
Figure 2: An example on interpretation of ice chart "Egg".
Below tables show the ice concentration in tabular form on April 1st and April 30th.
Table 1: Table showing Ice concentration on April 1st
File Date Total Ice concentration Partial
Concentrations Stage of
Development Form (Floe Size)
4/1/2018 10 2 | 8 1. | 7 5 | 8
4/1/2019 10 5 | 5 1. | 7 5 | 8
4/1/2020 9+ - 7 8
4/1/2021 9+ - 7 8
4/1/2022 10 - 7 8
4/1/2023 9+ - 7 8
Table 2: Table showing Ice concentration on April 30th
File Date Total Ice concentration Partial
Concentrations Stage of
Development Form (Floe Size)
4/30/2018 9+ 2 | 8 1. | 7 5 | 8
4/30/2019 - - - -
4/30/2020 2 - 7 4
4/30/2021 - - - -
4/30/2022 9+ 2 | 8 1. | 7 5 | 8
4/30/2023 8 - 7 4
In summary, the typical conditions in the operational area of the Ranger III are Fast Ice 30-70 mm in the vicinity of Houghton and Grey Ice 15-30 cm surrounding Isle Royale.
B. ABS ICE CLASS SELECTION FOR OPERATING PROFILE
ABS classifies the ships required to break first year ice into 6 ice categories namely IAA, IA, IB, IC, ID & IE. The guide for selection of ice-class can be made using the below table created from
ABS MVR 2024 6-1-4/3.1.
Table 3: Guide for selection of ice-class (ABS MVR 2024 Part 6-1-4/3.1)
Ice Class Definition
Ice Class IAA Vessels with such structure, engine output and other properties that they are normally capable of navigating in difficult ice conditions without the assistance of icebreakers
Ice Class IA Vessels with such structure, engine output and other properties that they are capable of navigating in difficult ice conditions, with the assistance of icebreakers when necessary
Ice Class IB Vessels with such structure, engine output and other properties that they are capable of navigating in moderate ice conditions, with the assistance of icebreakers when necessary
Ice Class IC Vessels with such structure, engine output and other properties that they are capable of navigating in light ice conditions, with the assistance of icebreakers when necessary
Ice Class ID Vessels with such structure, engine output and other properties that they are capable of navigating in very light ice conditions, with the assistance of icebreakers when necessary
Ice Class IE Vessel with such structure, engine output and other properties that they are capable of navigating in extremely light ice conditions, with the assistance of icebreakers when necessary
Typical ice conditions experienced by the RANGER III are late-season ice along Isle Royale docks. The ice along the Isle Royale docks is free to move along the shoreline and back into the channel when acted upon by a vessel. Typically, this ice is thin first year ice approximately 30mm in thickness.
C. ICE CLASS FOR RANGER IV
Based on the historical ice data, conversations with the operators, and videos of the RANGER III, the design team determined ABS Ice Class IE best fit the RANGER IV’s operational need.
This summary assumes that the RANGER IV will not be responsible for breaking thick plate ice.
The NPS advised LHG the RANGER III, which is not ice classed and whose hull is not ice strengthen, utilizes the USCG’s ice breaking capabilities to clear the Houghton Channel, but the cutter will not be available to clear near the ISRO docks. Even though we have been advised of no ice breaking damage incidents on the Ranger III, we have used the operating profile strictly as presented by NPS to develop the following conclusions.
Reasons for proceeding with IE ice class:
1. Considering the RANGER IV operation from Mid-Apr as the ice is thawing and the USCG will clear a channel in Houghton, the RANGER IV conditions will experience very light drift ice conditions.
2. The data collection point is in Lake Portage which is not along the operational route of the vessel. Lake Portage is shallow and has vast swathes of open area which cause the flow of water draining from Lake Superior to Lake Michigan through the canal to slow increasing the chance of ice formation.
3. The design team had interactions with the operators of RANGER III and have also seen the videos of ice breaking. After reviewing the information, the design team is convinced that the total ice breaking capability is not required for more than few inches at a time.
4. Considering above, to break thin ice, the Ranger IV's bow is reinforced with higher-grade steel, enhancing its ability to cut through spring ice without raising the vessel's overall ice class.
5. The RANGER III’s hull is not ice strengthened, and the propulsion equipment is not ice classed. The NPS has not reported any equipment or structural failure due to ice operations.
6. The ice charts studied during Apr 1st to Apr 30th have a decreasing trend of ice concentrations, in some years the ice has completely cleared off by end of April. Any ice classification more than IE may result in significant weight and equipment modifications which is an over design for a vessel of this class and mission.
Based on previous design experience, the design team intends to proceed with IE ice class to perform the intended tasks.
D. ATTACHMENTS
The following serves as supporting documentation for this report.
• Attachment A – Ice Charts – April 1st (2018-2023)
• Attachment B – Ice Charts – April 30th (2018-2023)
E. REFERENCES
• ABS Marine Vessel Rules January 2024, Part 6 – Specialized items and Systems
• US National Ice Center – Great Lakes – Ice Charts
ATTACHMENT A
Ice Charts – April 1st (2018-2023)
Revision (-)
DISTRIBUTION Statement C: Distribution authorized to the U.S. Government agencies and their Contractors. Other
DATA RIGHTS: This report, drawing, design, concept, and specification are the intellectual property of Loch Harbour
Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C and contain information which is proprietary. The rights defined below are reserved by Loch Harbour Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C.
The United States Government’s rights to use, modify, reproduce, release, perform, display, or disclose these technical data are unrestricted. Any reproduction of technical data or portions thereof marked with this legend must also
Nikhil Chutturu Rectangle
ATTACHMENT B
Ice Charts – April 30th (2018-2023)
Revision (-)
DISTRIBUTION Statement C: Distribution authorized to the U.S. Government agencies and their Contractors. Other
DATA RIGHTS: This report, drawing, design, concept, and specification are the intellectual property of Loch Harbour
Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C and contain information which is proprietary. The rights defined below are reserved by Loch Harbour Group, LLC, and/or R.R.P CONSULTING ENGINEERS, L.L.C.
The United States Government’s rights to use, modify, reproduce, release, perform, display, or disclose these technical data are unrestricted. Any reproduction of technical data or portions thereof marked with this legend must also
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