Crane Boom Recoil from Sudden Loss of Load

Catastrophic crane boom backwards collapse caused by crane boom recoil from sudden loss of load can be avoided, even if crane boom stops are ineffective, or not fitted.  The video below explains the simple calculations needed.  These calculations should form part of a Naval Architectural Analysis for a mobile crane mounted on a barge.

Boom Backwards Recoil Collapse in Marine Salvage

Some of the sections from the video are shown below, beginning with an amateur video of a crawler crane boom backwards collapse on a barge during a salvage operation in 2018.

The next clip illustrates the crane boom recoil issue with a 1/12th scale model.  In the first part a heavy load is dropped when the model boom stops are not connected.  in the second part, the boom stops (which have springs in the model) are connected.

The Excel analysis finds both a closed form analytical solution to the maximum boom recoil angle and also provides a time domain integration of the boom pendant wire sudden tension reduction from the lost load.

The next clip shows the close comparison of the boom pendant wire tension change in the first 0.5 seconds after the load is dropped.  Both Excel and OrcaFlex predict that the tension becomes zero after 0.22 seconds.  During this time the pendant tension is accelerating the boom’s angular velocity.

The time domain motion of the boom angle is compared in the next clip, then the Excel closed form solutions for a range of dropped load sizes and initial boom angles is shown, for two different pendant wire sizes.

Floating Service Load Chart

A Floating Service Load Chart is required by US Army Corps of Engineers (USACE) Manual EM-385-1-1, Safety and Health Requirements, November 2014, for all mobile cranes mounted on barges, pontoons, etc.  This can be provided by the Load Handling Equipment (LHE) manufacturer.

Naval Architectural Analysis

If a manufacturer’s Floating Load Service Chart is not available, a floating service load chart may be developed and provided by a qualified registered engineer or naval architect, competent in the field of floating cranes.  STA provides the NAA Service.

Additional Codes and Standards

In developing a Floating Service Load Chart and de-rating any floating crane, the following codes and standards must be considered:

The relevant FRs do not mention crane boom recoil or boom stops.  ASME 30.5 specifies that boom stops shall be provided on mobile cranes to resist the boom falling backwards.  No design guidelines are given.  ASME 30.8 has similar wording.  P-307 requires boom stops to be checked, but does not mention precautions to be taken if the crane does not have boom stops. Similarly, EM-385 notes that a crane should have boom stops.  NAVCRANECEN Instruction 11450.2 gives a specific analysis to be performed to check if crane boom recoil will result in contact with the boom stops.  The load to be used in the analysis is stated with reference to the Floating Service Load Chart.

An example of a Floating Service Load Chart is shown below, with the crane boom recoil limitation on maximum hook loads also included.

An example of a safe lift at a high (77º) boom angle, on a barge mounted mobile crawler crane without boom stops is shown below.

A detailed structural dynamic analysis of the boom and the boom stops can be performed using OrcaFlex, as shown in the next example clip.

SUMMARY

  • Calculation of maximum crane boom recoil angle from closed-form analysis equations in Excel
  • Calculation of maximum safe loads at high boom angles
  • Prevent backwards crane boom recoil accidents
  • Time domain “instant” solutions in Excel
  • Detailed time domain simulations relatively quick with OrcaFlex
  • Structural checks using non-linear dynamic analysis of boom stops and booms performed in OrcaFlex
  • Low cost, high value, advanced structural engineering calculations save lives and save money.

FEA with SimScale to Optimize an Articulated Navaid

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Finite element analysis of the non-linear foam buoyancy in floats for articulated navaid
(articulated navigation aids). Click picture below to go to article on Simscale website.
Simscale Article 1

STA has used many FEA tools.  The cloud-based FEA service from Simscale is new, efficient and high quality.

Offshore Renewable Energy – USA

A presentation made to the SUT Offshore Site Investigation and Geotechnics Committee(OSIG) and Offshore Renewables Committee (OR) of SUT-US on August 30, 2018 is shown below.

  • Falling renewable power costs signal a real paradigm shift in the competitiveness of different power generation options. This includes cheaper electricity from renewables as a whole, as well as the very low costs now being attained from the best solar PV and onshore wind projects.
  • This talk presents historical data and trends for electricity costs produced by offshore turbines.  The big picture of future offshore renewable energy developments in the US will be presented.
  • —Regulations and Permitting

    —Financing a New Type of Market

    —Infrastructure (Ports and Fabrication, Installation, New Vessel Types)

    —High Maintenance Costs (New Vessel Types)

    —Technical Challenges of Grid Interconnection

    —Poor Existing Supply Chain and Offshore Wind Expertise

    —The Jones Act and Lack of Existing In-Country Installation Vessels

    —Aesthetic Issues, Radar Interference, Wildlife Concerns

Backwards Stability of Crane Booms

A rigging failure resulted in sudden release of the hook load.  The boom was raised high and crane was on a barge.  The boom collapsed backwards over the cab.  Late 2017, BVI.

Bil Stewart produces Naval Architectural Reports (NAA) and Floating Service Load Charts for mobile cranes used on barges.  The video above, was not one of STA’s projects.

The above Floating Service Load Chart is for a crane and barge unit in Greece.

Cruise Ship Collision Barrier

A new type of Cruise Ship collision control barrier is under design and development.  The design brings a very large cruise ship (or any other vessel) gradually to a stop, converting the vessel’s initial kinetic energy to potential energy, which is stored in two structures on either side of the barrier.

Cruise Ship Collision

Cruise Ship Collision Barrier – Simulation with OrcaFlex

Hydrodynamic analysis with OrcaFlex is used to confirm and improve upon closed form analytical solutions developed by STA.

Designs have been developed for cruise ships up to 333m length with gross tonnage 150,000 and a starting collision velocity  of 6 knots.

Efforts on the project were interrupted in September 2017, by Hurricanes Harvey, which effected our Houston office, and Irma, which effected our Caribbean interests.

5 Examples of Oil and Gas Software Offered by Stewart Technology Associates

OrcaFlex SP Squall Analysis tlu3-with-suezmax

Stewart Technology Associates has a long history of providing quality engineering services for the marine industry and off-shore oil and gas industries, and it specializes in design and analysis of marine structures and fluid dynamics. Some of the specific services offered include hydrodynamic analysis, mooring analysis, anchor analysis, rig design and analysis, riser design and analysis, finite element analysis, marine training simulations, financial assessments, risk assessments, forensic analysis, and oil spill containment and clean-up consulting.

As part of its service in the off-shore oil and gas industries, Stewart Technology associates has developed a wide variety of custom oil and gas software that represents the industry standard in marine training simulations, design and analysis of marine structures, and tools for laying out and installing marine systems.

Here is an overview of several of the custom oil and gas software applications offered by Stewart Technology Associates:

1) STA JUSIM Jack-Up Simulator Software

Used in conjunction with custom simulation hardware, the jack-up simulator helps new users learn how to operate jack-up oil platforms in a safe and efficient manner while accurately simulating real-world scenarios, including common operational problems. In the physical simulator, trainees operate a jack-up control panel that is similar to the control panel in existing operational designs, and it is mounted on a tilting table that can simulate the movements and attitude of an actual jack-up rig to within less than 1/10 of a degree of accuracy.

sim01

The software simulates realistic conditions such as leg damage to the jack-up and punch-through, allowing the operators to experience and prepare for emergencies that may happen in real-life scenarios. The software runs on a standard PC and can operate alone or in conjunction with a physical simulator.

2) STA 2POINT

STA 2POINT is a software program designed to simulate the effects of both lateral and longitudinal forces on a vessel that is moored in a two-point mooring system. It calculates the forces and the loads created by wind, ocean currents, and waves on the vessel, and is designed for situations where the vessel is in shallow water and there is little or no pretension applied to the mooring lines. It accounts for stretching of the mooring lines and uses the US Navy’s methods for determining wind and current loads.

3) STA SPM

This software simulates the mooring forces at work on a single vessel that is moored at a single-point mooring system, taking into account the forces of the wind, currents, and waves on the vessel according to direction. It is designed specifically for tankers that are moored in single-point systems, using either bow hawsers or bow turrets. A second tanker, offloading in tandem, can also be simulated with either astern thrust or assistance from a tug boat.

 

4) STA ANCHOR

STA ANCHOR is a computer program designed to calculate the holding capacity and predict the drag anchor embedment of a particular anchor design. The operator selects from a variety of standard anchor sizes and geometries, and customize the geometry according to a particular design. Combined with the specific characteristics of the sea floor, the program determines the holding capacity of the anchor and the vertical and horizontal forces at work on the structure of the design. This enables the anchor to be tested and redesigned to meet specific requirements. The software can be used in conjunction with other programs to perform a full analysis of the anchor design and related hardware, including the STA CHAIN, STA PILE and STA PULLOUT programs.

5) STA LIFTBOAT

This software is used by a variety of liftboat manufacturers and designers, as well as the US Coastguard, to help design three-legged liftboats and to analyze and verify the design. It simulates the forces at work on the lift boat when it is in the fully elevated position, including the forces of wind on the structure above the water, as well as the effects of the currents and waves on the legs. It independently analyzes wind loads on each section of the exposed structure, including the hull, the crane, and the superstructure. Many of the inputs can be customized to match the design of the structure and the characteristics of its location, including the loading condition of the liftboat, the water depth, the amount of pad penetration into the sea floor, the stiffness of the pad restraint provided by the soil, and many other variables. With this software, the design can be tested in real-world conditions and be altered to meet the criteria required for the application.

These are just a few of the many custom oil and gas software programs that are written, designed and distributed by Stewart Technology Associates. Some of the software can be customized for specific use cases on request, for an additional fee. Stewart Technology Associates also works extensively with OrcaFlex, and they distribute custom software from third parties on request.

In addition to oil and gas software, Stewart Technology Associates provides a wide range of other consulting services for both the oil and gas industry and many other marine-related industries.

 

Sources:

 

http://www.rigzone.com/training/insight.asp?insight_id=339

8 Services Provided by Our Marine Consultants

Any structures that operate in a marine environment, including offshore drilling rigs, risers, mooring systems, marine vessels, wave power systems, and offshore wind generator facilities, provide unique design and operational challenges that often require significant resources and ingenuity to overcome. Many companies rely on the extensive knowledge and experience of marine consultants to help provide critical analysis of these problems and devise piratical, cost-efficient solutions.

8 Services Provided by Our Engineer Consultants image

Specializing in marine and offshore structures, fluid dynamics and related disciplines, here are just a few of the services that our marine consultants at Stewart Technology Associates can provide:

1) Hydrodynamic Analysis

Hydrodynamic analysis is used to accurately simulate the forces at work on a structure in a marine environment. This includes the movement of the waves, the action of the tides, the effects of undersea pressures, turbulence from structures or seafloor features, and the effect of high winds and inclement weather. By learning how these forces affect a structure, its design can be improved to eliminate possible failure points and to reduce costs and maintenance requirements. Hydrodynamic analysis can be used to examine both new and existing designs, and it can also be used after a maritime accident to help determine the cause of the problem.

2) Finite Element Analysis

Finite element analysis can be used to model how real-world conditions will affect the operation of a product or of a component of a larger system when subjected to forces such as vibration, heat, high pressures, fluid flow or other physical challenges. The results of the modeling can be used to improve the product’s design, reducing component failures and wear that can shorten its lifespan or lead to increased maintenance costs. Finite element analysis can also make a product safer, and help to determine the cause of failure in an existing design.

3) Structural Design and Analysis

STA can help design and analyze marine structures, such as drilling rigs, jack-ups and liftboats, to make sure that they will perform efficiently and safely in a specified environment. They can work directly with a client to create a structure that will withstand the forces in a particular marine or sub-sea environment safely, while increasing productivity and reducing long-term costs. They can also analyze existing designs to improve their structural performance, productivity and safety.

4) Riser Design and Analysis

Risers are one of the most critical components in an offshore oil drilling or production platform. They carry mud and drilling fluids to the well during drilling operations and carry oil and gas to the surface during production operations. To operate safely while maximizing production, they must be able to withstand the movement and pressure below the surface, while moving fluids efficiently. Engineer consultants can be used to design an efficient riser system for production or drilling operations, determining what type of riser will be needed, rigid, flexible or hybrid, effective mooring solutions, what equipment will be required and other factors. They can also improve the efficiency of fluid moment withing the riser, increasing production, and analyze existing designs to suggest structural, efficiency and safety improvements.

5) Anchor Performance Analysis

Anchors are critical to securing marine vessels and other structures in place temporarily, permanently or semi-permanently, and if they fail to perform adequately, they can allow vessels to drift off course or to collide with other structures, leading to injuries, property damage, productivity losses or environmental concerns. To perform effectively, the design of an anchor must take into account the weight and movement of the vessel, the surface conditions and the composition of the sea floor. With an anchor analysis, engineer consultants can model the forces at work on the anchor and suggest improvements that will make it stronger, safer and more effective.

6) Mooring Design and Analysis

Mooring systems in the offshore oil industry are critical to keep the platform in place during operation, to secure tankers while transferring oil and gas and to secure other vessels as needed. They must be able to withstand the weight of the vessel or platform, while compensating for motion at the surface of the sea and keeping transfer pipes and equipment safe. Engineering consultants can analyze the design of a mooring system, including the anchors, mooring lines and surface structure, ensuring that it can perform both safely and effectively. They can also create new designs for specific applications and analyze the performance of transfer systems.

7) Oil Spill Clean-Up and Containment

Oil spills can have far-reaching consequences, from polluting the water supply and harming animal and plant life, to making beaches less inviting and hurting economies that depend on fishing or tourism. When the worst does happen, the key to minimizing the damage is to contain the oil as close as possible to the source and to clean it up as quickly as possible. Engineering consultants can help to design effective measures for both containing the oil and cleaning it up, including effective boom systems to contain the oil and techniques that can adequately model the currents and conditions at the site to make clean-up more successful and efficient.

8) Forensic Analysis

After a maritime accident or an oil spill, the original cause of the accident can be difficult to determine and, often, there are many contributing factors that make the origin even less clear. Engineer consultants can use hydrodynamic analysis, finite element analysis and other techniques, along with advanced software and extensive knowledge of marine systems, to analyze the events leading up to the accident, as well as the accident itself and its effects, to help determine the original cause. This information can be used to determine liabilities in the aftermath of the accident, to improve designs to prevent future accidents and to establish new safety protocols and programs that can help avoid or mitigate such incidents in the future.

 

Sources:

http://stewart-usa.com

http://stewart-usa.com/overview.php

http://usa.oceana.org/sites/default/files/tourism_impacts_fact_sheet_9-8-15.pdf

5 Ways Oil and Gas Software Can Help Your Business

Published  by Stewart Technologies on April 20, 2016

There are hundreds of software solutions for the oil and gas industry that can make the job of finding, drilling for, and producing oil and gas much easier, safer, and cost-effective. The software solutions range from programs that automate control systems or provide safety solutions, such as man overboard warnings, to software that is designed to map out and determine the viability of a formation, or to analyze the structure of marine systems and the effect of hydrodynamic forces on them.

Oil and gas software such as Orcaflex, Orcina, Saic, or Atkins can be used to design and analyze marine systems such as oil rigs, liftboats, jack-ups, anchors, pipelines, single-point moorings and other marine systems, making sure that they will operate safely in the chosen environment and have decent lifespans. GIS, or geological information systems software, can help to collate available geological data, such as maps, well logs, mud logs, and other data, and use it to determine the overall make-up and viability of a formation, including cross-section generation and analysis. Other types of software can manage production, logistics supplies, or specific hardware systems.

Here are just a few of the ways that oil and gas software can help to improve your company’s operations:

#1 Design Analysis

Whether you are designing a semi-submersible rig, a jack-up or floating platform, the right oil and gas software can help you to perfect the design long before it goes into production, and put it through its paces virtually, with thorough software-based testing and analysis.

This allows you to make sure that your design will work as expected in the worst conditions, such as when the wind is blowing in hurricane-force gusts, or the waves are hitting the rig with incredible force. Using the information from the virtual testing and analysis, you can improve the design of the right to withstand wave action, sub-sea pressures, tidal forces, and the worst weather conditions to be expected at the site.

Once you are sure that your design meets all of your needs and specifications, you can then put it into production. By analyzing the design with oil and gas software such as OrcaFlex first, you can avoid costly production mistake that costs thousands or more to fix, as well as tedious maintenance issues further down the line.

#2 Hydrodynamic Analysis

From the largest oil rigs to the smallest mooring points and clamps, every marine system is prone to structural damage through the forces of wave action, tidal forces, inclement weather, large sub-sea pressures, corrosion and other issues unique to marine environments. In order to be cost-effective, any system used in a marine environment must strike a balance between longevity and total cost of ownership. Structures built to handle the worst forces in a marine environment may be too expensive to be cost-effective, while less expensive structures may cost your more over their lifetimes due to increased maintenance costs.

Oil and gas software such as OrcaFlex can help you perform an accurate hydrodynamic analysis on just about any type of marine system, allowing you to study how the forces of the marine environment will affect the system. By doing a thorough analysis, you can improve the design of your mooring system, pipeline, riser system or other marine equipment. This will help you to design components that stand up to the unique stresses of the marine environment better, reducing maintenance costs, extending the lifespan of the equipment, and keeping your total cost of ownership reasonable.

#3 Financial Assessments

Oil and gas software can help your company plan your oil and gas exploration and production operations from start to finish. This includes estimating the required investment in equipment, such as oil rigs, drilling risers, pipelines, mooring systems, to analyzing geological data and estimating well viability and output. It can help you to determine the total costs associated with the operation and the potential profits.

It can also help you to determine possible risks, such as oil spills, environmental damage, injuries and accidents, and help you to determine the best courses of action in each situation and possible costs associated with them. With oil and gas software, you can have complete control over every aspect of your burliness, with instantaneous access to detailed information, analysis and reports that are critical to your operations.

#4 Marine Simulations

Oil and gas software can also help during training and certification of employees and other staff. Software simulators, such as jack-up or ballast control simulators can help new operator become familiar with the control systems in such equipment without risk to the physical equipment or crew. This reduce liability and overall training costs, and allows you to safely train your crew with fewer risks.

Jack-up simulators can mimic nearly any step in the operation of a jack-up rig, including how the system responds to problems such as a broken leg, a punch through, or poor contact with the sea floor. Ballast simulators allow the operator to empty or fill the ballasts of a ship or rig in accordance to weather conditions, preventing the system from sinking or tipping over in rough seas.

#5 Forensic Analysis

If there is an accident or oil spill at one of your sites, oil and gas software can help you to determine the cause of the accident, who is responsible and how to prevent such problems in the future. Software tools such as hydrodynamic analysis can be critical in the analysis of the problem and in finding a solution, and software like OrcaFlex can make the process much easier.

By making your equipment safer through hydrodynamic analysis and by preventing accidents in the future, you can reduce your company’s liabilities and increase long-term profits.

Oil and gas software, such as OrcaFlex, GIS software and training simulators, can help your business run more efficiently, safely and smoothly. It can help you to design better structures that can easily withstand the unique forces in a marine environment, it can help you to improve your training processes, it can prevent accidents and it can analyze financial risks to your company and help reduce operational costs.

 

Sources:

http://www.rigzone.com/training/insight.asp?insight_id=339&c_id=24

The 4 Basic Components of Single Point Moorings

Published  by Stewart Technologies on March 18, 2016

During off-shore oil and gas production operations, single point moorings provide a safe way to offload petroleum products to tankers, operating as both a buoy system to keep the ship in position and as a connection to the sub-sea pipeline and riser system to move the petroleum products from the production platform to the tanker.

Single point mooring systems have several critical parts, and they must all operate together properly to safely and efficiently load the tanker. They must also be able to withstand large forces from the movement of the ship on the ocean, wave action, tidal forces, surface weather, undersea pressures and both horizontal and vertical movements.

Here are some of the most important parts of single point moorings, and how they help to complete the off-loading process successfully:

#1 The Buoy

The buoy typically consists of a set of legs that connect it to the sea floor and a body section, which is located at the surface. The body can freely spin around the leg section, due to a roller-bearing system that permits free rotation. This allows ships that are moored to the buoy to freely move around it, according to the movements of the ocean.

Without this ability to rotate, ships attached to the buoy would exert large amounts of extra force on the buoy system, potentially resulting in a failure of the lines anchoring the ship to the buoy, or the lines anchoring the buoy to the sea floor. During loading operations, this could cause safety problems, as the ship breaks free and moves unexpectedly, or environmental consequences if it causes a spill of petroleum products.

A properly-designed buoy system should be able to handle all the horizontal, vertical and rotational forces exerted on it while safely delivering oil or gas to the tanker.

#2 The Anchoring System

The buoy is attached to the seafloor with either anchors or a pile system, in most cases. Anchors provide a temporary attachment system by sinking a large mass, such as concrete, to the sea floor to provide a stationary weight, by embedding into the seafloor itself, or by attaching to an existing sub sea feature, such as a large mass of rock or a crevice. For a more permanent attachment system, piles can be driven into the seafloor to provide a solid anchoring system.

Once the anchor and the buoy are in place, anchor chain, or sometimes synthetic or metal cables, are run from the anchors or piles on the seafloor up to the buoy itself, providing a secure attachment.

Each of the components in the anchoring system must be able to withstand the corrosive effects of salt water, as well as the natural forces of the ocean, including waves, weather, and pressure. Most anchoring systems are built to withstand some small amounts of movement, which helps prevent fatigue and the structural failures that can result from the forces acting against the system.

#3 The Petroleum Loading System

The buoy is connected to a pipeline system that is located on the seafloor. This pipeline carries oil or gas from the well and distributes it through a pipeline end manifold to a system of risers that bring it to the surface of the ocean. These risers are typically flexible, allowing them to move along with the ocean currents and the movements of the buoy.

At the surface, the risers connect to the buoy, and the oil and gas is routed through a swivel system in the buoy’s body, allowing the output connections for the petroleum products to swivel along with the moments of the ship. The final connection from the buoy to the tanker is typically made with a floating hose system, which features breakaway connectors that prevent oil spills if the ship moves too far away from the buoy.

The swivel system contains a number of valves and seals that prevent oil or gas leaks, as well as supplemental connections for power, data or electrical signals in many cases. All of the seals and electrical connections are constantly subjected to rotational forces, friction and some horizontal and vertical movement. They must be carefully designed to withstand all of the stresses experienced during operation while minimizing the amount of maintenance required and the associated costs.

#4 Ship Mooring System

The deck of the buoy features a mooring point, to which one or two synthetic ropes are attached, depending on the size of the ship. The ropes are extended out to the tanker, where they are connected to a chafe chain that is extended from the tanker. The connection allows the ship to rotate around the buoy, and the floating hose system moves along with the ship. Each component must be carefully designed to handle the weight of the ship and the forces exerted on it by the movement of the ocean.

Optional Components

Typically, the buoy will have a boat dock for personnel to easily access the deck, as well as fenders or bumpers to prevent damage to the buoy. It may also have an integrated power system, weather equipment, navigation aids, or cranes and other equipment for maneuvering large loads, as well as safety equipment.

Improving the Design of Single Point Moorings

To design a long-lasting and structurally-sound single point mooring system, it is wise to invest in both a structural design analysis and a hydrodynamic analysis. By scrutinizing the structural components and modeling how each behaves under the conditions present in a marine environment, including wave action, high pressures, tidal forces, variable weather and corrosive forces, the design of each component can be optimized to ensure that it will perform well under the worst conditions, with a suitable design life and minimal maintenance. With hydrodynamic analysis, every possible component can be modeled and improved, from the shackles connecting the mooring lines to the anchoring system, to the buoy itself.

With a properly-designed single point mooring system, operational costs can be significantly reduced, production efficiency can be increased, safety can be improved and the environment can be better protected.


Sources:

http://stewart-usa.com/mooring-analysis.php
http://stewart-usa.com/hydrodynamic-analysis.php
http://petrofed.winwinhosting.net/upload/18Sep10/1.pdf
http://www.rigzone.com/training/insight.asp?insight_id=308&c_id=17

 

5 Things To Explore With Single Point Moorings

[Posted on March 23rd, 2015 by Bill Stewart]

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Single point moorings can be used as a station within the ocean for ships and oil rigs as a halfway point between where they need to be and land. It can help to save time and costs. The mooring is essentially a floating platform and when choosing to work with or build such a system, there are various things to explore.

The Materials

There are several aspects that go into single point moorings. This includes the anchor that is at the bottom of the ocean, the mooring line, and the connectors. The mooring line is ultimately what gets connected to the anchor and then goes up to the floating structure at the top of the water’s surface. The material of this line can vary from wire to chain to synthetic fiber rope. What is actually used will depend upon an array of environmental factors.

The right material needs to be used for the situation, otherwise it is possible for the line to break, causing the mooring to free float without being tethered down.

The Anchors

The entire system of a mooring relies on the strength of the anchor or anchors at the ocean floor. Analysis of soil composition needs to be made so the anchors are properly seated into the soil. There are such types of anchors as vertical load, suction, and drag embedment that can be used. If the wrong anchor is used, it can drag across the ocean floor, causing the mooring to sway and relocate.

The Actual System

There are several systems that can be used with a mooring. The ASCE will often speak about the different systems based upon the type of water that is being used. Single point moorings are ones that include a buoy, anchoring elements, mooring, and a product transfer system. These are most commonly used within the oil drilling industry, but it can be used for other industries as well. It’s important to understand that this is one of the many systems out there. Others include catenary, taut leg, dynamic positioning, and spread.

Positioning

Some consideration has to be made as to where the mooring will be positioned. It cannot be placed simply anywhere in the ocean. There needs to be a plan as to where it goes based upon where the work locations are and where the land is. Further analysis of the ocean floor conditions may also need to be made.

Environmental Factors

Understanding the environmental factors are ultimately the most critical part of looking at a mooring. Some of the various factors that need to be considered include ocean waves, currents, and wind.

Analysis has to include the various environmental conditions of a project to determine how the mooring should be built and using what materials. At Stewart Technology Associates, we offer various analytical reports that can be useful.

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