ASTM F1878-98(2015)
(Guide)Standard Guide for Escort Vessel Evaluation and Selection
Standard Guide for Escort Vessel Evaluation and Selection
SIGNIFICANCE AND USE
4.1 This guide presents some methodologies to predict the forces required to bring a disabled ship under control within the available limits of the waterway, taking into account local influences of wind and sea conditions. Presented are methodologies to determine the control forces that an escort vessel can reasonably be expected to impose on a disabled ship, taking into account the design of the ship, transit speed, winds, currents, and sea conditions. In some instances, this guide presents formulae that can be used directly; in other instances, in which the interaction of various factors is more complicated, it presents analytic processes that can be used in developing computer simulations.
4.2 Unlike the more traditional work of berthing assistance in sheltered harbors or pulling a “dead ship” on the end of a long towline, the escorting mission assumes that the disabled ship will be at transit speed at the time of failure, and that it could be in exposed waters subject to wind, current, and sea conditions.
4.3 The navigational constraints of the channel or waterway might restrict the available maneuvering area within which the disabled ship must be brought under control before it runs aground or collides with fixed objects in the waterway (see allision).
4.4 The escort mission requires escort vessel(s) that are capable of responding in timely fashion and that can safely apply substantial control forces to the disabled ship. This entails evaluation of the escort vessel's horsepower, steering and retarding forces at various speeds, maneuverability, stability, and outfitting (towing gear, fendering, and so forth). This guide can be used in developing escort plans for selecting suitable escort vessel(s) for specific ships in specific waterways.
4.5 The methodologies and processes outlined in this guide are for performance-based analyses of escort scenarios. This means that the acceptability of a vessel (or combination of vessels) for escorting is based up...
SCOPE
1.1 This guide covers the evaluation and selection of escort vessels that are to be used to escort ships transiting confined waters. The purpose of the escort vessel is to limit the uncontrolled movement of a ship disabled by loss of propulsion or steering to within the navigational constraints of the waterway. The various factors addressed in this guide also can be integrated into a plan for escorting a given ship in a given waterway. The selection of equipment also is addressed in this guide.
1.2 This guide can be used in performance-based analyses to evaluate:
1.2.1 The control requirement of a disabled ship,
1.2.2 The performance capabilities of escort vessels,
1.2.3 The navigational limits and fixed obstacles of a waterway,
1.2.4 The ambient conditions (wind and sea) that will impact the escort response, and
1.2.5 The maneuvering characteristics of combined disabled ship/escort vessel(s).
1.3 This guide outlines how these various factors can be integrated to form an escort plan for a specific ship or a specific waterway. It also outlines training programs and the selection of equipment for escort-related activities.
1.4 A flowchart of the overall process for developing and implementing an escort plan is shown in Fig. 1. The process begins with the collection of appropriate data, which are analyzed with respect to the performance criteria and in consultation with individuals having local specialized knowledge (such as pilots, waterway authorities, interest groups, or public/private organizations, and so forth). This yields escort vessel performance requirements for various transit speeds and conditions; these are embodied in the ship's escort plan. When the time comes to prepare for the actual transit, the plan is consulted in conjunction with forecast conditions and desired transit speed to select and dispatch the appropriate escort vessel (or combination of vessels). A pre-escort conference ...
General Information
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F1878 − 98 (Reapproved 2015) An American National Standard
Standard Guide for
Escort Vessel Evaluation and Selection
This standard is issued under the fixed designation F1878; 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 (or combination of vessels). A pre-escort conference is con-
ducted to ensure that all principal persons (ship master, pilot,
1.1 This guide covers the evaluation and selection of escort
and escort vessel masters) have a good understanding of how
vessels that are to be used to escort ships transiting confined
tomakeasafetransitandinteractintheeventofanemergency.
waters. The purpose of the escort vessel is to limit the
uncontrolledmovementofashipdisabledbylossofpropulsion 1.5 This guide addresses various aspects of escorting, in-
or steering to within the navigational constraints of the cluding several performance criteria and methodologies for
waterway. The various factors addressed in this guide also can analyzing the criteria, as well as training, outfitting, and other
be integrated into a plan for escorting a given ship in a given escort-related considerations. This guide can be expanded as
waterway. The selection of equipment also is addressed in this appropriate to add new criteria, incorporate “lessons learned”
guide. as more escorting experience is gained in the industry, or to
include alternative methodologies for analyzing the criteria.
1.2 This guide can be used in performance-based analyses
to evaluate: 1.6 This guide addresses physical control of the disabled
1.2.1 The control requirement of a disabled ship, ship with the assistance of the escort vessel(s). Other possible
1.2.2 The performance capabilities of escort vessels, functions, such as firefighting, piloting, or navigational
1.2.3 The navigational limits and fixed obstacles of a redundancy,areoutsidethescopeofthisguide.Also,thisguide
waterway, was developed for application to oceangoing ships in coastal
1.2.4 The ambient conditions (wind and sea) that will waterways; it is not suitable for application to barge strings in
impact the escort response, and riverine environments.
1.2.5 Themaneuveringcharacteristicsofcombineddisabled
1.7 The values stated in inch-pound units are to be regarded
ship/escort vessel(s).
as standard. No other units of measurement are included in this
1.3 This guide outlines how these various factors can be standard.
integratedtoformanescortplanforaspecificshiporaspecific
waterway. It also outlines training programs and the selection 2. Referenced Documents
of equipment for escort-related activities.
2.1 Code of Federal Regulations Document:
1.4 A flowchart of the overall process for developing and
33 CFR Part 168 Escort Vessels for Certain Tankers, Final
implementing an escort plan is shown in Fig. 1. The process
Rule
begins with the collection of appropriate data, which are
2.2 IMO Resolutions:
analyzed with respect to the performance criteria and in
IMO Resolution A.601(15) Provision and Display of Ma-
consultation with individuals having local specialized knowl-
neuvering Information on Board Ships
edge (such as pilots, waterway authorities, interest groups, or
IMO Resolution A.751(18) Interim Standards for Ship Ma-
public/private organizations, and so forth). This yields escort
neuverability
vessel performance requirements for various transit speeds and
2.3 Marine Safety Committee Circulars:
conditions; these are embodied in the ship’s escort plan. When
MSC Circular 389 Interim Guidelines for Estimating Ma-
the time comes to prepare for the actual transit, the plan is
neuvering Performance in Ship Design
consulted in conjunction with forecast conditions and desired
MSC Circular 644 Explanatory Notes to the Interim Stan-
transitspeedtoselectanddispatchtheappropriateescortvessel
dards for Ship Maneuverability
This guide is under the jurisdiction of Committee F25 on Ships and Marine
Technology and is the direct responsibility of Subcommittee F25.07 on General AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
Requirements. 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
Current edition approved May 1, 2015. Published June 2015. Originally www.access.gpo.gov.
approved in 1998. Last previous edition approved in 2009 as F1878 – 98 (2009). Available from the International Maritime Organization (IMO), 4, Albert
DOI: 10.1520/F1878-98R15. Embankment, London, SE1 7SR, UK, http://www.imo.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1878 − 98 (2015)
FIG. 1 Flowchart of the Overall Process for Developing and Implementing an Escort Plan
3. Terminology theperformanceenvelopeofanescortvesselatdifferenttransit
speeds and under a range of weather and sea conditions.
3.1 For purposes of clarity within this guide, the vessel
being escorted is referred to as the “ship” or “disabled ship.” 3.3 The terms “conventional propulsion” and “omni-
The vessel accompanying the ship as its escort is referred to as directional propulsion” refer to propulsion systems of the
the “escort vessel.” escort vessel.
3.3.1 Conventional Propulsion System—The propulsive
3.2 The escorting measures addressed in this guide are
thrust is fixed in a fore/aft direction.
based on performance.
3.3.2 Omni-Directional Propulsion System—The propulsive
3.2.1 The term “performance measure” refers to perfor-
thrust is steerable in any direction (360°) around the hull.
mance capabilities that must be possessed by the escort
Examples are the azimuthing Z-drive screw propeller system
vessel(s) in controlling the disabled ship within a particular
and the vertical axis cycloidal system.
waterway. This requires a holistic analysis of the combined
maneuvering dynamics of the escort vessel(s) and ship within 3.4 The terms “direct mode” and “indirect mode” refer to
the waterway in ambient weather and sea conditions. two towing modes for exerting control forces on a disabled
Performance-based requirements involve extensive preplan- ship via towline from the escort vessel.
ning and analyses, but offer greater assurance that the escort 3.4.1 Direct Mode—The towline force is derived directly
vessel(s) actually will be effective. The methodologies and from the escort vessel’s propulsion system. In general, the
processes presented in this guide can be used in determining towline orientation is over the bow or over the stern of the
F1878 − 98 (2015)
escort vessel, and only the propulsive thrust vector parallel to 3.6.7 escort vessel, n—a vessel that is assigned to stand by
the towline axis is effective on the disabled ship. or is dedicated to travel in close proximity to a designated ship
3.4.2 Indirect Mode—The towline force is derived from the to provide timely assistance should the ship experience a
escort vessel’s hull drag as it is pulled along behind the propulsion or steering failure, or both. The escort vessel has
disabled ship (similar to a drag chute). High-performance appropriate fendering and towing gear to provide emergency
escort vessels should have sufficient stability so that they can assist capability relative to the demand of the disabled ship.
turn approximately sideways to the towline without capsizing
3.6.8 grounding, n—impact of a ship’s hull with the sea
(tripping), thereby substantially increasing their hull drag and,
bottom.
consequently, increasing their towline force. The propulsion
3.6.9 maneuvering coeffıcients, n—a set of numerical coef-
system of these escort vessels is used indirectly to maintain an
ficients the are used in polynomial representations of the forces
over-the-side towline orientation (rather than pull directly on
acting on a ship in terms of the instantaneous state of the ship.
the towline itself). In the indirect mode, specially designed
3.6.10 oppose maneuver, n—an escort vessel maneuver in
escort vessels can kite off to one side or the other of the
which the assisting escort vessel(s) apply maximum steering
disabled ship’s stern, thereby imposing substantial steering
force to a disabled ship to turn the ship against its rudder. In
forces on the ship as well as retarding forces to slow it down.
this maneuver, the objective is to return the ship to its original
3.5 The terms “parameters” and “constraints” refer to addi-
heading by opposing the rudder forces.
tional conditions that define the escort scenario and response.
3.6.11 propulsion failure, n—the ship is unable to propel or
3.5.1 Parameters—Additional details that are specified as
actively stop itself.
part of the performance criteria to define more fully the
performance “problem” that must be solved by the escort 3.6.12 response times, n—the sequence of time delays
vessel(s). Parameters are used to customize the performance following a disabling failure on a transiting ship before the
criteria to reflect a particular waterway or a specific perfor- escort vessel(s) can apply corrective forces.
mance objective. Examples of parameters include an initial
3.6.13 rescue tow, n—a maneuver in which the escort vessel
ship speed at moment of failure, or winds, currents, and sea
makes up lines and pulls the disabled ship; undertaken after all
state conditions that must be assumed during the escort
forward way has come off the disabled ship.
response.
3.6.14 retard maneuver, n—an escort vessel maneuver in
3.5.2 Constraints—Limitations associated with “solving”
which the assisting escort vessel(s) apply maximum braking
the performance problem. Examples of constraints include the
force to a disabled ship. In this maneuver, the objective is to
stability limits of the escort vessel (which limit how much
take speed off the ship as quickly as possible by pulling astern.
towline heeling moment the escort vessel can tolerate),
The control of a ship’s heading is not an objective. Also
strength limits of the ship’s bollards (which limit how much
referred to as arrest.
towline force can be applied), or the navigable limits of the
3.6.15 rudder failure, n—theship’srudderislockedatsome
waterway (which limit how much maneuvering room is avail-
angle or it is swinging uncontrollably.
able).
3.6.16 ship track/course, n—the path covered by the ship’s
3.6 Definitions:
center of gravity during a voyage, a waterway transit, or a
3.6.1 allision, n—a collision with a fixed object.
maneuver.
3.6.2 allowable reach, n—the straight line distance forward
3.6.17 tactical diameter, n—the distance, perpendicular to
from the designated ship, parallel to its course direction, to a
the original course direction, between the ship’s center of
point at which a grounding of an allision would occur.
gravity at the start and at the end of a 180° heading change.
3.6.3 allowable transfer, n—the straight line distance from
3.6.18 zigzag maneuver, n—a test used to measure the
the designated ship, perpendicular to its course direction, to a
effectiveness of the rudder to initiate and check course
point at which a grounding or an allision would occur.
changes. The maneuver is described in MSC Circular 644,
3.6.4 assist maneuver, n—an escort vessel maneuver in
Section 2.2.
which the assisting escort vessel(s) apply maximum steering
3.7 Evaluation and Selection Variables:
forcetoadisabledshiptoenhancetheturnoftherudder.Inthis
3.7.1 transit speeds, n—the speed of the escorted ship
maneuver,theobjectiveistomaketheradiusofturnoftheship
measured through the water. The transit speed takes into
as small as possible.
account tidal and wind-driven currents. Transit speed is not
3.6.5 emergency scenarios, n—the complete description of
over ground (SOG) as measured by Global Positioning System
the failure, the navigational situation, and the emergency assist
(GPS), Loran, or radar.
response.
3.7.2 bollard pull, n—the maximum sustainable force that
3.6.6 escort operating area, n—a subregion of the
the escort vessel is able to develop while pulling on a towline
waterway, harbor, bay, and so forth, that has been identified as
attached to a stationary object. The forward and astern bollard
the region in which the escort vessel(s) will stand by or
pulls are individually specified.
accompany the designated ship. The subregion may contain
locations that would require timely escort vessel assistance 3.7.3 dynamic pull (at a particular speed), n—themaximum
should the ship experience a propulsion or steering failure, or sustainable force that the escort vessel is able to develop while
both. moving through the water at a particular speed.
F1878 − 98 (2015)
3.7.4 transfer, n—the distance perpendicular to the original 4.5.3 Turning—the ability to turn the disabled ship within
track that a ship’s center of gravity travels in a 90° change in specified parameters, and
heading. 4.5.4 Holding steady—the ability to hold the disabled ship
on a steady course under specified parameters.
3.7.5 advance, n—the distance parallel to the original track
that a ship’s center of gravity travels in a 90° change of 4.6 The “specified parameters” are additional details that
heading.
must be factored into the performance analysis. These param-
eters might be specified by a regulatory agency imposing the
3.7.6 performance limits, n—limits of performance mea-
escort requirement, by a study group evaluating the feasibility
sures such that under all circumstances, the use of vessels,
of escorting in a particular waterway, or by the ship or escort
equipment, or crew shall not place the life and safety of
vessel operators themselves to define the performance enve-
individuals in jeopardy. No applicable federal or state regula-
lope of their vessels. Some examples of these parameters are:
tions should be exceeded in determining escort vessel perfor-
4.6.1 A ship transit speed (at the moment of failure);
mance capabilities and limits.
4.6.2 The failure scenario (rudder failure alone, or simulta-
neous rudder/propulsion failure, degree of failure, and so
4. Significance and Use
forth);
4.1 This guide presents some methodologies to predict the
4.6.3 Navigational constraint within which the disabled ship
forcesrequiredtobringadisabledshipundercontrolwithinthe
must be brought under control (such as allowable advance and
available limits of the waterway, taking into account local
transfer, cross-track error, and so forth);
influences of wind and sea conditions. Presented are method-
4.6.4 Wind, current, and sea conditions; and
ologies to determine the control forces that
...
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.
Designation: F1878 − 98 (Reapproved 2009) F1878 − 98 (Reapproved 2015)An American National Standard
Standard Guide for
Escort Vessel Evaluation and Selection
This standard is issued under the fixed designation F1878; 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
1.1 This guide covers the evaluation and selection of escort vessels that are to be used to escort ships transiting confined waters.
The purpose of the escort vessel is to limit the uncontrolled movement of a ship disabled by loss of propulsion or steering to within
the navigational constraints of the waterway. The various factors addressed in this guide also can be integrated into a plan for
escorting a given ship in a given waterway. The selection of equipment also is addressed in this guide.
1.2 This guide can be used in performance-based analyses to evaluate:
1.2.1 theThe control requirement of a disabled ship,
1.2.2 theThe performance capabilities of escort vessels,
1.2.3 theThe navigational limits and fixed obstacles of a waterway,
1.2.4 theThe ambient conditions (wind and sea) that will impact the escort response, and
1.2.5 theThe maneuvering characteristics of combined disabled ship/escort vessel(s).
1.3 This guide outlines how these various factors can be integrated to form an escort plan for a specific ship or a specific
waterway. It also outlines training programs and the selection of equipment for escort-related activities.
1.4 A flowchart of the overall process for developing and implementing an escort plan is shown in Fig. 1. The process begins
with the collection of appropriate data, which are analyzed with respect to the performance criteria and in consultation with
individuals having local specialized knowledge (such as pilots, waterway authorities, interest groups, or public/private
organizations, and so forth). This yields escort vessel performance requirements for various transit speeds and conditions; these
are embodied in the ship’s escort plan. When the time comes to prepare for the actual transit, the plan is consulted in conjunction
with forecast conditions and desired transit speed to select and dispatch the appropriate escort vessel (or combination of vessels).
A pre-escort conference is conducted to ensure that all principal persons (ship master, pilot, and escort vessel masters) have a good
understanding of how to make a safe transit and interact in the event of an emergency.
1.5 This guide addresses various aspects of escorting, including several performance criteria and methodologies for analyzing
the criteria, as well as training, outfitting, and other escort-related considerations. This guide can be expanded as appropriate to
add new criteria, incorporate “lessons learned” as more escorting experience is gained in the industry, or to include alternative
methodologies for analyzing the criteria.
1.6 This guide addresses physical control of the disabled ship with the assistance of the escort vessel(s). Other possible
functions, such as firefighting, piloting, or navigational redundancy, are outside the scope of this guide. Also, this guide was
developed for application to oceangoing ships in coastal waterways; it is not suitable for application to barge strings in riverine
environments.
1.7 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
2. Referenced Documents
2.1 Code of Federal Regulations Document:
33 CFR Part 168—Escort Vessels for Certain Tankers, Final Rule168 Escort Vessels for Certain Tankers, Final Rule
2.2 IMO Resolutions:
IMO Resolution A.601(15)—Provision and Display of Maneuvering Information on Board ShipsA.601(15) Provision and
Display of Maneuvering Information on Board Ships
This guide is under the jurisdiction of Committee F25 on Ships and Marine Technology and is the direct responsibility of Subcommittee F25.07 on General Requirements.
Current edition approved Nov. 1, 2009May 1, 2015. Published January 2010June 2015. Originally approved in 1998. Last previous edition approved in 20042009 as
F1878 - 98F1878 – 98 (2009).(2004). DOI: 10.1520/F1878-98R09.10.1520/F1878-98R15.
Available from the U.S. Government Printing Office Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.732 N. Capitol St., NW,
Mail Stop: SDE, Washington, DC 20401, http://www.access.gpo.gov.
Available from the International Maritime Organization, 4 Organization (IMO), 4, Albert Embankment, London, SE1 7SR U.K.7SR, UK, http://www.imo.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1878 − 98 (2015)
FIG. 1 Flowchart of the Overall Process for Developing and Implementing an Escort Plan
IMO Resolution A.751(18)—Interim Standards for Ship ManeuverabilityA.751(18) Interim Standards for Ship Maneuverability
2.3 Marine Safety Committee Circulars:
MSC Circular 389/Interim Guidelines for Estimating Maneuvering Performance in Ship Design389 Interim Guidelines for
Estimating Maneuvering Performance in Ship Design
MSC Circular 644/Explanatory Notes to the Interim Standards for Ship Maneuverability 644 Explanatory Notes to the Interim
Standards for Ship Maneuverability
3. Terminology
3.1 For purposes of clarity within this guide, the vessel being escorted is referred to as the “ship” or “disabled ship.” The vessel
accompanying the ship as its escort is referred to as the “escort vessel.”
3.2 The escorting measures addressed in this guide are based on performance.
3.2.1 The term “performance measure” refers to performance capabilities that must be possessed by the escort vessel(s) in
controlling the disabled ship within a particular waterway. This requires a holistic analysis of the combined maneuvering dynamics
of the escort vessel(s) and ship within the waterway in ambient weather and sea conditions. Performance-based requirements
involve extensive preplanning and analyses, but offer greater assurance that the escort vessel(s) actually will be effective. The
methodologies and processes presented in this guide can be used in determining the performance envelope of an escort vessel at
different transit speeds and under a range of weather and sea conditions.
F1878 − 98 (2015)
3.3 The terms “conventional propulsion” and “omni-directional propulsion” refer to propulsion systems of the escort vessel.
3.3.1 Conventional Propulsion System—The propulsive thrust is fixed in a fore/aft direction.
3.3.2 Omni-Directional Propulsion System—The propulsive thrust is steerable in any direction (360°) around the hull. Examples
are the azimuthing Z-drive screw propeller system and the vertical axis cycloidal system.
3.4 The terms “direct mode” and “indirect mode” refer to two towing modes for exerting control forces on a disabled ship via
towline from the escort vessel.
3.4.1 Direct Mode—The towline force is derived directly from the escort vessel’s propulsion system. In general, the towline
orientation is over the bow or over the stern of the escort vessel, and only the propulsive thrust vector parallel to the towline axis
is effective on the disabled ship.
3.4.2 Indirect Mode—The towline force is derived from the escort vessel’s hull drag as it is pulled along behind the disabled
ship (similar to a drag chute). High-performance escort vessels should have sufficient stability so that they can turn approximately
sideways to the towline without capsizing (tripping), thereby substantially increasing their hull drag and, consequently, increasing
their towline force. The propulsion system of these escort vessels is used indirectly to maintain an over-the-side towline orientation
(rather than pull directly on the towline itself). In the indirect mode, specially designed escort vessels can kite off to one side or
the other of the disabled ship’s stern, thereby imposing substantial steering forces on the ship as well as retarding forces to slow
it down.
3.5 The terms “parameters” and “constraints” refer to additional conditions that define the escort scenario and response.
3.5.1 Parameters—Additional details that are specified as part of the performance criteria to define more fully the performance
“problem” that must be solved by the escort vessel(s). Parameters are used to customize the performance criteria to reflect a
particular waterway or a specific performance objective. Examples of parameters include an initial ship speed at moment of failure,
or winds, currents, and sea state conditions that must be assumed during the escort response.
3.5.2 Constraints—Limitations associated with “solving” the performance problem. Examples of constraints include the
stability limits of the escort vessel (which limit how much towline heeling moment the escort vessel can tolerate), strength limits
of the ship’s bollards (which limit how much towline force can be applied), or the navigable limits of the waterway (which limit
how much maneuvering room is available).
3.6 Definitions:
3.6.1 allision, n—a collision with a fixed object.
3.6.2 allowable reach, n—the straight line distance forward from the designated ship, parallel to its course direction, to a point
at which a grounding of an allision would occur.
3.6.3 allowable transfer, n—the straight line distance from the designated ship, perpendicular to its course direction, to a point
at which a grounding or an allision would occur.
3.6.4 assist maneuver, n—an escort vessel maneuver in which the assisting escort vessel(s) apply maximum steering force to
a disabled ship to enhance the turn of the rudder. In this maneuver, the objective is to make the radius of turn of the ship as small
as possible.
3.6.5 emergency scenarios, n—the complete description of the failure, the navigational situation, and the emergency assist
response.
3.6.6 escort operating area, n—a subregion of the waterway, harbor, bay, and so forth, that has been identified as the region in
which the escort vessel(s) will stand by or accompany the designated ship. The subregion may contain locations that would require
timely escort vessel assistance should the ship experience a propulsion or steering failure, or both.
3.6.7 escort vessel, n—a vessel that is assigned to stand by or is dedicated to travel in close proximity to a designated ship to
provide timely assistance should the ship experience a propulsion or steering failure, or both. The escort vessel has appropriate
fendering and towing gear to provide emergency assist capability relative to the demand of the disabled ship.
3.6.8 grounding, n—impact of a ship’s hull with the sea bottom.
3.6.9 maneuvering coeffıcients, n—a set of numerical coefficients the are used in polynomial representations of the forces acting
on a ship in terms of the instantaneous state of the ship.
3.6.10 oppose maneuver, n—an escort vessel maneuver in which the assisting escort vessel(s) apply maximum steering force
to a disabled ship to turn the ship against its rudder. In this maneuver, the objective is to return the ship to its original heading by
opposing the rudder forces.
3.6.11 propulsion failure, n—the ship is unable to propel or actively stop itself.
3.6.12 response times, n—the sequence of time delays following a disabling failure on a transiting ship before the escort
vessel(s) can apply corrective forces.
3.6.13 rescue tow, n—a maneuver in which the escort vessel makes up lines and pulls the disabled ship; undertaken after all
forward way has come off the disabled ship.
F1878 − 98 (2015)
3.6.14 retard maneuver, n—an escort vessel maneuver in which the assisting escort vessel(s) apply maximum braking force to
a disabled ship. In this maneuver, the objective is to take speed off the ship as quickly as possible by pulling astern. The control
of a ship’s heading is not an objective. Also referred to as arrest.
3.6.15 rudder failure, n—the ship’s rudder is locked at some angle or it is swinging uncontrollably.
3.6.16 ship track/course, n—the path covered by the ship’s center of gravity during a voyage, a waterway transit, or a maneuver.
3.6.17 tactical diameter, n—the distance, perpendicular to the original course direction, between the ship’s center of gravity at
the start and at the end of a 180° heading change.
3.6.18 zigzag maneuver, n—a test used to measure the effectiveness of the rudder to initiate and check course changes. The
maneuver is described in MSC Circular 644, Section 2.2.
3.7 Evaluation and Selection Variables:
3.7.1 transit speeds, n—the speed of the escorted ship measured through the water. The transit speed takes into account tidal
and wind-driven currents. Transit speed is not over ground (SOG) as measured by Global Positioning System (GPS), Loran, or
radar.
3.7.2 bollard pull, n—the maximum sustainable force that the escort vessel is able to develop while pulling on a towline attached
to a stationary object. The forward and astern bollard pulls are individually specified.
3.7.3 dynamic pull (at a particular speed), n—the maximum sustainable force that the escort vessel is able to develop while
moving through the water at a particular speed.
3.7.4 transfer, n—the distance perpendicular to the original track that a ship’s center of gravity travels in a 90° change in
heading.
3.7.5 advance, n—the distance parallel to the original track that a ship’s center of gravity travels in a 90° change of heading.
3.7.6 performance limits, n—limits of performance measures such that under all circumstances, the use of vessels, equipment,
or crew shall not place the life and safety of individuals in jeopardy. No applicable federal or state regulations should be exceeded
in determining escort vessel performance capabilities and limits.
4. Significance and Use
4.1 This guide presents some methodologies to predict the forces required to bring a disabled ship under control within the
available limits of the waterway, taking into account local influences of wind and sea conditions. Presented are methodologies to
determine the control forces that an escort vessel can reasonably be expected to impose on a disabled ship, taking into account the
design of the ship, transit speed, winds,
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.