ASTM F2936-23

Standard Specification for Chocks, Ship Mooring, Cast Steel

ABSTRACT
This specification covers the principal dimensions and materials of closed chocks for installation on ships used for mooring. It specifies the classification of chocks, their dimension requirements, and strength requirements. It also demonstrates the proper horizontal and vertical loading for Type A and Type B chocks.
SCOPE
1.1 This specification covers the principal dimensions and materials of closed chocks for installation on ships used for mooring.  
1.2 Chocks can be used with either wire rope or fiber and synthetic ropes.  
1.3 Chocks are for mounting directly on a deck, seat (foundation), or for mounting in a bulwark.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2023
• ICS: 47.020.50 - Deck equipment and installations
• Technical Committee: F25 - Ships and Marine Technology
• Drafting Committee: F25.01 - Structures

Relations

• Refers: ASTM A27/A27M-20 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-May-2020
• Refers: ASTM A27/A27M-19 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Sep-2019
• Refers: ASTM A27/A27M-17 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-May-2017
• Refers: ASTM A27/A27M-13(2016) - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Sep-2016
• Refers: ASTM A27/A27M-13 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Nov-2013
• Refers: ASTM A27/A27M-10 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Oct-2010
• Refers: ASTM A27/A27M-08 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Oct-2008
• Refers: ASTM A27/A27M-05 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Mar-2005
• Refers: ASTM A27/A27M-03 - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 10-Apr-2003
• Refers: ASTM A27/A27M-95(2000) - Standard Specification for Steel Castings, Carbon, for General Application
• Effective Date: 01-Jan-2000

Overview

ASTM F2936-23: Standard Specification for Chocks, Ship Mooring, Cast Steel defines the key requirements for the design, material, dimensions, and performance of closed chocks intended for installation on ships used for mooring. Developed by ASTM International, this standard is critical to the shipbuilding and marine industries, ensuring that mooring chocks offer reliable strength and durability whether used with wire, fiber, or synthetic mooring lines. The specification provides detailed classification, size ranges, loading requirements, and surface finishing instructions for cast steel mooring chocks.

Key Topics

• Scope and Implementation

  • Covers closed chocks for ship mooring, installed on decks, seats (foundations), or bulwarks.
  • Suitable for use with wire, fiber, or synthetic mooring ropes.
  • All dimensions and measurements are presented in SI units, with no alternative units specified.

• Chock Classifications

  • Type I & Type III: Deck-mounted closed chocks.
    • Type I meets all specified dimensions.
    • Type III conforms to opening dimensions and required strength.
  • Type II & Type IV: Bulwark-mounted closed chocks.
    • Type II meets all specified dimensions.
    • Type IV conforms to opening dimensions and minimum strength.

• Strength and Dimension Requirements

  • Detailed tables specify nominal sizes, dimensions, safe working loads, and recommended rope diameters.
  • Strength calculations account for both horizontal and vertical load cases based on typical mooring operations.
  • Stress limits and geometric requirements ensure safe and reliable mooring solutions.

• Materials and Workmanship

  • Chocks must be manufactured from cast steel in line with ASTM A27/A27M.
  • Requirements for high-quality surface finish, with rope-contact areas for certain grades finished to minimize rope abrasion.
  • Products must be free from cracks, casting defects, and must undergo appropriate surface treatment and inspection.

Applications

The ASTM F2936-23 standard is essential for the following practical applications:

• Ship Mooring Hardware: Ensures the safety and performance of chocks used on commercial ships, navy vessels, and offshore platforms during mooring and towing operations.
• Shipbuilding and Repair: Provides guidance for designers and builders of new ships or during retrofitting and repair, ensuring consistency and reliability in hardware installations.
• Marine Equipment Sourcing: Enables ship owners and operators to confidently source mooring chocks that meet industry standards for strength, durability, and compatibility with various rope types.
• Safety Compliance: Helps stakeholders in the maritime industry comply with international safety and performance standards, reducing the risk of equipment failure or unsafe mooring practices.

Related Standards

To ensure comprehensive compliance and performance, ASTM F2936-23 references and complements these important standards:

• ASTM A27/A27M: Specification for Steel Castings, Carbon, for General Application - sets the material requirements for cast steel used in chock manufacturing.
• ANSI B 46.1: Surface Texture (Roughness, Waviness, Lay) - governs the rope contact area finishing, especially for fiber and synthetic mooring lines.

Other standards related to ship mooring fittings, marine hardware, or surface preparation may also enhance compliance and align with regulatory or class society requirements.

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Keywords: ship mooring chocks, closed chocks, cast steel, ASTM F2936, marine hardware, shipbuilding, mooring line fittings, safety standards, maritime compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F2936 − 23 An American National Standard
Standard Specification for
Chocks, Ship Mooring, Cast Steel
This standard is issued under the fixed designation F2936; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 mooring ring or pipe—a chock mounted in the bul-
wark and conforming to Type II and IV.
1.1 This specification covers the principal dimensions and
materials of closed chocks for installation on ships used for 3.1.4 rope contact area—that part of the fitting in contact
mooring. with the mooring line in normal mooring operations.
1.2 Chocks can be used with either wire rope or fiber and
4. Classification
synthetic ropes.
4.1 The size of the chocks will be identified by the nominal
1.3 Chocks are for mounting directly on a deck, seat
size “L” and “H” of the opening as shown in Table 1 and Table
(foundation), or for mounting in a bulwark.
2.
1.4 The values stated in SI units are to be regarded as
4.2 Chocks are furnished in types as follows:
standard. No other units of measurement are included in this
4.2.1 Type I—Deck mounted as shown in Fig. 1 and
standard.
conforming to all dimensions in Table 1.
1.5 This international standard was developed in accor-
4.2.2 Type II—Bulwark mounted as shown in Fig. 2 and
dance with internationally recognized principles on standard-
conforming to all dimensions in Table 2.
ization established in the Decision on Principles for the
4.2.3 Type III—Deck mounted, conforming only to dimen-
Development of International Standards, Guides and Recom-
sions “L” and “H” of Table 1 and is of adequate strength to at
mendations issued by the World Trade Organization Technical
least meet 7.2 requirement.
Barriers to Trade (TBT) Committee.
4.2.4 Type IV—Bulwark mounted, conforming only to di-
2. Referenced Documents
mensions “L” and “H” of Table 2 and is of adequate strength
to at least meet 7.2 requirement.
2.1 ASTM Standards:
A27/A27M Specification for Steel Castings, Carbon, for
4.3 Chocks shall be furnished in either of the following
General Application
grades:
2.2 ANSI Standards:
4.3.1 Grade 1—Surface finish shall be in the as cast
B 46.1 Surface Texture (Roughness, Waviness, Lay)
condition.
4.3.2 Grade 2—Surface finish in way of rope contact shall
3. Terminology
be in accordance with 8.2.
3.1 Definitions of Terms Specific to This Standard:
3.1.1 bulwark—a structural enclosure along the edge of the
5. Ordering Information
ship to serve as a rail.
5.1 Orders for chocks under this specification shall include
3.1.2 closed chock—a metal flared ring-like fitting mounted
this standard, date, and the following:
on a ship, through which mooring lines pass to moor a ship.
5.1.1 Descriptive information (size, material, etc.) of moor-
ing lines,
1 5.1.2 Quantity (number) of chocks required,
This specification is under the jurisdiction of ASTM Committee F25 on Ships
and Marine Technology and is the direct responsibility of Subcommittee F25.01 on
5.1.3 Size (opening, L × H),
Structures.
5.1.4 Type and grade,
Current edition approved May 1, 2023. Published May 2023. Originally
ɛ1
approved in 2012. Last previous edition approved in 2018 as F2936 – 12 (2018) . 5.1.5 Primer and coating, if any (see 8.3), and
DOI:10.1520/F2936-23.
5.1.6 Marking.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
6. Materials and Manufacture
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
6.1 Material shall be cast steel in accordance with Specifi-
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. cation A27/A27M, Grade 60–30.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2936 − 23
TABLE 1 Dimension Requirements (see Fig. 1)
(Units: mm)
Nominal size
l l l l H H H R R R R
1 2 3 4 1 2 3 1 2 3
L×H×D
250×200×214 488 453 76 265 427 368 108 100 219 160 108
300×250×286 614 565 89 330 551 481 144 125 282 212 144
350×250×333 716 660 114 403 601 525 168 125 308 232 168
400×250×381 820 754 139 475 652 553 192 125 335 236 192
450×250×381 870 804 164 524 652 553 192 125 335 236 192
500×250×381 920 854 189 574 652 553 192 125 335 236 192
400×250×428 870 796 139 500 701 609 216 125 360 268 216
450×250×428 920 846 164 550 701 609 216 125 360 268 216
500×250×428 970 896 189 600 701 609 216 125 360 268 216
500×400×428 970 896 176 600 851 759 216 200 435 343 216
A
500×250×525 1068 1000 190 652 798 675 264 125 409 286 264
A
500×400×525 1068 1000 193 652 948 825 264 200 484 361 264
B
500×250×525 1074 1000 176 652 801 680 264 125 412 291 264
B
500×400×525 1074 1000 179 652 951 830 264 200 487 366 264
Welding leg Rope
Nominal size SWL Calculated
R R R d T length diameter
4 5 6 1 C
L×H×D weight (kg)
z kN ton (Recommend)
250×200×214 86 150 128 108 22 6 226 23 18 73
300×250×286 118 180 154 144 26 6.5 422 40 24 142
350×250×333 138 200 170 168 30 7.5 549 56 28 222
400×250×381 156 250 214 192 36 9 687 70 32 310
450×250×381 156 250 214 192 36 9 706 72 32 322
500×250×381 156 250 214 192 36 9 765 78 32 337
400×250×428 178 250 212 216 38 9.5 883 90 36 434
450×250×428 178 250 212 216 38 9.5 912 93 36 452
500×250×428 178 250 212 216 38 9.5 932 95 36 472
500×400×428 178 250 212 216 38 9.5 893 91 36 528
A
500×250×525 224 320 280 264 40 10 1148 117 44 657
A
500×400×525 224 320 280 264 40 10 1158 118 44 724
B
500×250×525 218 320 274 264 46 11.5 1413 144 44 753
B
500×400×525 218 320 274 264 46 11.5 1383 141 44 825
A
SWLs shown in the Table are for reference only. “SWL” may be adjusted depending on the actual loading conditions, and the actual marking is to be per the agreement
between the user and the manufacturer.
B
Rope diameter (Recommend) is only for reference based on bending ratio of rope through the chock is 12 times.
C
Calculated weight is for reference only.
6.2 For Types III and IV the manufacturer shall certify that 7.1.2 Case 2—Vertical loading (see Figs. 4-6).
strength of the chock will at least meet 7.2 requirement, and
7.2 The combined stress is limited to 85 % of the yield
that it is suitable for the mooring lines specified in the ordering
stress of the material.
information.
8. Workmanship, Finish, and Appearance
6.3 Casting shall be smooth, fine grain, and free of cracks,
hot tears, and blow holes, detrimental to end use. Defects
8.1 Casting shall be sand, grit, or shot blasted to a gray
having an area larger than 625 mm and a depth of more than metal finish to remove all loose scale. All mold flashing shall
10 % of the thickness in way thereof will be cause for rejection.
be removed and radii shall be fair so as to present an even
Smaller defects in way of rope contact shall be welded and surface.
finished smooth. Where applicable, welding shall be
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: F2936 − 12 (Reapproved 2018) F2936 − 23 An American National Standard
Standard Specification for
Chocks, Ship Mooring, Cast Steel
This standard is issued under the fixed designation F2936; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Keywords section was editorially added in March 2018.
1. Scope
1.1 This specification covers the principal dimensions and materials of closed chocks for installation on ships used for mooring.
1.2 Chocks can be used with either wire rope or fiber and synthetic ropes.
1.3 Chocks are for mounting directly on a deck, seat (foundation), or for mounting in a bulwark.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A27/A27M Specification for Steel Castings, Carbon, for General Application
2.2 ANSI Standards:
B 46.1 Surface Texture (Roughness, Waviness, Lay)
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 bulwark—a structural enclosure along the edge of the ship to serve as a rail.
3.1.2 closed chock—a metal flared ring-like fitting mounted on a ship, through which mooring lines pass to moor a ship.
3.1.3 mooring ring or pipe—a chock mounted in the bulwark and conforming to Type II and IV.
This specification is under the jurisdiction of ASTM Committee F25 on Ships and Marine Technology and is the direct responsibility of Subcommittee F25.01 on
Structures.
Current edition approved March 1, 2018May 1, 2023. Published April 2018May 2023. Originally approved in 2012. Last previous edition approved in 20122018 as F2936
ɛ1
– 12. DOI:10.1520/F2936-12R18E01.12 (2018) . DOI:10.1520/F2936-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2936 − 23
3.1.4 rope contact area—that part of the fitting in contact with the mooring line in normal mooring operations.
4. Classification
4.1 The size of the chocks will be identified by the nominal size “L” and “H” of the opening as shown in Table 1 and Table 2.
4.2 Chocks are furnished in types as follows:
4.2.1 Type I—Deck mounted as shown in Fig. 1 and conforming to all dimensions in Table 1.
4.2.2 Type II—Bulwark mounted as shown in Fig. 2 and conforming to all dimensions in Table 2.
4.2.3 Type III—Deck mounted, conforming only to dimensions “L” and “H” of Table 1 and is of adequate strength to at least meet
7.2 requirement and the requirements of Sections requirement.6 to 10.
4.2.4 Type IV—Bulwark mounted, conforming only to dimensions “L” and “H” of Table 2 and is of adequate strength to at least
meet 7.2 requirement and the requirements of Sections requirement.6 to 10.
4.3 Chocks shall be furnished in either of the following grades:
4.3.1 Grade 1—Surface finish shall be in the as cast condition.
4.3.2 Grade 2—Surface finish in way of rope contact shall be in accordance with 8.2.
TABLE 1 Dimension Requirements (see Fig. 1)
(Units: mm)
Nominal size
l l l l H H H R R R R
1 2 3 4 1 2 3 1 2 3
L×H×D
250×200×214 488 453 76 265 427 368 108 100 219 160 108
300×250×286 614 565 89 330 551 481 144 125 282 212 144
350×250×333 716 660 114 403 601 525 168 125 308 232 168
400×250×381 820 754 139 475 652 553 192 125 335 236 192
450×250×381 870 804 164 524 652 553 192 125 335 236 192
500×250×381 920 854 189 574 652 553 192 125 335 236 192
400×250×428 870 796 139 500 701 609 216 125 360 268 216
450×250×428 920 846 164 550 701 609 216 125 360 268 216
500×250×428 970 896 189 600 701 609 216 125 360 268 216
500×400×428 970 896 176 600 851 759 216 200 435 343 216
A
500×250×525 1068 1000 190 652 798 675 264 125 409 286 264
A
500×400×525 1068 1000 193 652 948 825 264 200 484 361 264
B
500×250×525 1074 1000 176 652 801 680 264 125 412 291 264
B
500×400×525 1074 1000 179 652 951 830 264 200 487 366 264
Welding leg Rope
Nominal size SWL Calculated
R R R d T length diameter
4 5 6 1 C
L×H×D weight (kg)
z kN ton (Recommend)
250×200×214 86 150 128 108 22 6 226 23 18 73
300×250×286 118 180 154 144 26 6.5 422 40 24 142
350×250×333 138 200 170 168 30 7.5 549 56 28 222
400×250×381 156 250 214 192 36 9 687 70 32 310
450×250×381 156 250 214 192 36 9 706 72 32 322
500×250×381 156 250 214 192 36 9 765 78 32 337
400×250×428 178 250 212 216 38 9.5 883 90 36 434
450×250×428 178 250 212 216 38 9.5 912 93 36 452
500×250×428 178 250 212 216 38 9.5 932 95 36 472
500×400×428 178 250 212 216 38 9.5 893 91 36 528
A
500×250×525 224 320 280 264 40 10 1148 117 44 657
A
500×400×525 224 320 280 264 40 10 1158 118 44 724
B
500×250×525 218 320 274 264 46 11.5 1413 144 44 753
B
500×400×525 218 320 274 264 46 11.5 1383 141 44 825
A
SWLs shown in the Table are for reference only. “SWL” may be adjusted depending on the actual loading conditions, and the actual marking is to be per the agreement
between the user and the manufacturer.
B
Rope diameter (Recommend) is only for reference based on bending ratio of rope through the chock is 12 times.
C
Calculated weight is for reference only.
F2936 − 23
TABLE 2 Dimensions Requirement (see Fig. 2)
(Units: mm)
Nominal size
l l H H R R R R R R
1 2 1 2 1 2 3 4 5
L×H×D
250×200×214 516 441 466 306 100 233 153 108 96 150
300×250×286 638 554 588 410 125 294 205 144 128 180
350×250×333 736 646 636 449 125 318 224.5 168 150 200
400×250×381 834 736 684 450 125 342 225 192 172 250
450×250×381 884 786 684 450 125 342 225 192 172 250
500×250×381 934 836 684 450 125 342 225 192 172 250
400×250×428 882 778 732 515 125 366 257.5 216 194 250
450×250×428 932 828 732 515 125 366 257.5 216 194 250
500×250×428 982 878 732 515 125 366 257.5 216 194 250
500×400×428 982 878 882 665 200 441 332.5 216 194 250
500×250×525 1078 976 828 551 125 414 275.5 264 240 320
500×400×525 1078 978 978 701 200 489 350.6 264 240 320
500×250×525 1078 976 828 554 125 414 277 264 238 320
500×400×525 1078 978 978 704 200 489 352 264 238 320
Calculated
Welding leg length SWL
Nominal size Rope diameter
R d d T θ weight
6 1 2
L×H×D (Recommend)
z z kN ton A
1 2 (kg)
250×200×214 138 108 80 12 44° 6 5 226 23 18 49
300×250×286 164 144 100 16 44° 8 6.5 422 40 24 100
350×250×333 182 168 120 18 55° 9 7 549 56 28 141
400×250×381 230 192 120 20 47° 10 8 687 70 32 184
450×250×381 230 192 120 20 47° 10 8 706 72 32 194
500×250×381 230 192 120 20 47° 10 8 765 78 32 202
400×250×428 228 216 120 2
...