TheNavalArch Interview Series: Capt Robin Perera
TheNavalArch's Interview Series is an endeavor to get insights from the best engineering and business brains in the industry and present them to its users for the larger benefit of the maritime community. Leaders share their experiences and ideas that readers can gain...
Offshore Installation Vessels Stability Considerations
OFFSHORE INSTALLATION VESSELS STABILITY CONSIDERATIONS By Alan Crowle, BSc, MSc, MScbyRes, CEng, CMarEng, FRINA, FMAREST, FSCMS University of Exeter, College of Engineering, Renewable Energy Group INTRODUCTION The temporary phases of an offshore structure transport...
TheNavalArch Interview Series: Mr Victor Valera
TheNavalArch's Interview Series is an endeavor to get insights from the best engineering and business brains in the industry and present them to its users for the larger benefit of the maritime community. Leaders share their experiences and ideas that readers can gain...
TheNavalArch Interview Series: Mr Steven Lu
Mr. Steven LuManaging DirectorEpoch Offshore Engineering (Shanghai) Co., Ltd. TheNavalArch's Interview Series is an endeavor to get insights from the best engineering and business brains in the industry, and present them to its users for the larger benefit of the...
TRANSPORT VESSELS FOR FLOATING WIND
By Alan Crowle, BSc, MSc, CEng, CMarEng, FRINA, FMAREST, FSCMS Masters by Researcher, University of Exeter, College of Engineering, Mathematics and Physical Sciences, Renewable Energy Group SUMMARY Floating wind turbine construction is a large logistical exercise. The...
TheNavalArch Interview Series: Mr. Balakrishna Menon
Mr. Balakrishna MenonEngineering Director Mooreast (Asia) Pte Ltd TheNavalArch's Interview Series is an endeavor to get insights from the best engineering and business brains in the industry, and present them to its users for the larger...
Floating Rice Fields, the quest for solutions to combat drought floods and rising sea levels
by Lim Soon Heng, BE, PE, FSSS, FIMarEST Founder President, Society of FLOATING SOLUTIONS (Singapore) Abstract Amazing as it seems, there is a case for growing rice on floating platforms in the sea. The capital expenditure to develop this is offset by the opportunity...
CAPSIZE OF LIFTBOAT IN TRANSIT
This paper was originally presented in the 27th Offshore Symposium, February 22nd, 2022, Houston, Texas Texas Section of the Society of Naval Architects and Marine Engineers It has been reproduced here for the readers of TheNavalarch INTRODUCTION In 1989 a Class 105...
FLOATING WIND TURBINES -TRANSPORTATION AND INSTALLATION ENGINEERING
By Alan Crowle, BSc, MSc, CEng, CMarEng, FRINA, FMAREST, FSCMS Masters by Researcher, University of Exeter, College of Engineering, Mathematics and Physical Sciences, Renewable Energy Group Summary Floating offshore wind turbines are an emerging source of marine...
Preparation for Dry-docking of an oil tanker: A Chief Engineer’s approach
Introduction Dry-docking of a vessel is required at every 5 yearly intervals to carry out inspection of hull, propeller and other components which are normally submersed in water all the time. This is a requirement by ship’s classification societies. However, some...
Using simple tools for efficient Passage Planning for seagoing vessels
Introduction Planning a vessel’s voyage is a critical detailed exercise, and the main goal is to ensure safe and efficient passage between two ports. The Master has the responsibility for the vessel voyage planning, but very often he delegates the actual voyage...
Designing a closed chock as per IACS rules
Introduction Chocks are used universally for mooring and towing operations on ships. For towing operations, Chocks are used for guiding the towing rope from the winch through the outer shell of the vessel to the tug. For mooring operations, the chock is used to...
The Optim22 method of hull optimization – Part 2
This is a follow-up article to the previous article on Framed Structures Optimization. 1.1 Abstract A previous article introduced the Optim22 method. This one adds additional background information plus 3 more case studies to...
The Optim22 Method of Weight Optimization of Framed Steel Structures
1 Abstract A semi-automated structural weight optimization system is presented for framed structures of post and beam construction which is based on basic structural member design principles. The approach is to adjust member properties in a manner that...
Combating rising seas with floating structures
Introduction Rising sea level is an existential threat for many coastal cities. The sea is rising subtly but relentlessly at an exponential rate. Many predictions of how high and how fast it will rise in the next 50 years have proved to be understated. According to...
How to identify the spoolpiece lifting points?
In the offshore construction industry, the connection between the newly installed pipeline and the riser is accomplished via a series of ‘spoolpieces’ (or spools). The spool is fabricated by welding pipe joints to form an L-shaped, Z-shaped, or possibly a straight...
The importance of clear decision support before marine operations
Our oceans are interspersed with human activities: be it fishing, marine transportation, or offshore operations. These operations usually involve assets worth multiple million dollars, be it the produce or the equipment or in most cases, the human life. Produce from...
Sea Pressure Loads Calculation based on DNV Rules
Introduction Sea pressure loads are an important factor in the structural design of a vessel. What is sea pressure load? As the term suggests, it is the external pressure on the vessel due to the surrounding sea. What kind of pressure it is, and how to...
A quick empirical method for resistance estimation of planing vessels
Resistance estimation for a vessel is a fundamental exercise in design of the vessel. Resistance is a property that depends on the vessel’s shape and form. A conventional ship-shaped vessel with a bulb will have completely different resistance characteristics compared...
Powering the maritime industry with Hydrogen – Part 2
Powering the shipping industry with hydrogen - Part 2: Hydrogen propulsion on a ship - opportunities and challenges Introduction In the Part 1 of this article, we explored the basic properties of Hydrogen as a fuel, and also the opportunities and challenges...
A simplified method of performing fatigue analysis of offshore structures
A simplified method of performing fatigue analysis of offshore structures Introduction An offshore structure is subject to environmental loads of waves, wind and current. By their nature, the resulting wave loads on the structure are cyclical. These cyclical...
Powering the shipping industry with hydrogen: opportunities and challenges (Part 1)
Part 1: About Hydrogen – Basics, Opportunities, and Challenges Of late, hydrogen has been generating quite a buzz in the energy sector with its possibility as a clean source of energy. The shipping sector is not untouched, and this article explores the possibilities...
The importance of analysis in nearshore pull-in operation in offshore wind farms
Introduction Over the last 10 years, the global wind energy business has increased manifold. In the next 5 years, the rate of installation is expected to accelerate. This is mostly driven by the opening up of Chinese and US markets. A primary chunk of this market is...
Vessel Draft Survey Accuracy
by Chris Zeringue, Owner, MTS Marine Techincal Surveyors The key to accuracy in a Vessel Draft Survey may very well be found in a hole in the ship. I boarded my...
How to use a ship’s hydrostatics to calculate its draft and trim
Introduction A ship’s hydrostatics, or hydrostats, is an oft used term in maritime parlance, and it refers to the characteristics when it is floating. What characteristics are these? How are these determined, and how can we read and understand them? Understanding...
Numerical integration methods for hull volume estimation
Introduction The hull of a ship is a complex 3D geometry, and finding out its simple properties like volume, centroid, etc. is not possible through simple formulae unlike standard shapes like cuboid or a cylinder. How do we find a property, say the volume of a...
Selecting the right Capstan for berthing a vessel
Introduction Capstans are frequently deployed mooring equipment used on all types of vessels. Capstans are berthing/mooring equipment used to multiply the pulling force on mooring ropes. Traditionally, Capstans were operated manually but in modern ships, they are...
How to do rule-based fitting calculations of a keyless propeller
Introduction A keyless propeller, as the name implies, requires no key for fastening the propeller on the cone of the propeller shaft. How is the torque then transferred to the propeller? The torque is transferred by the friction between the propeller and the...
Getting the right thickness of GRP laminate for your boats
Introduction GRP laminates are widely used in the fabrication of high-speed crafts and light crafts/boats globally. GRP stands for Glass Reinforced Plastic. As the name suggests, GRP contains glass fibers embedded into a plastic resin. This gives it higher strength,...
Designing Fillet Welds for Symmetrical Joint Sections
Introduction Fillet welds are the most commonly used weld types in marine structures. A fillet weld is used when there are two pieces of metal that are joined perpendicular to each other or at an angle. In this article, we will explore how to select the right size...
Designing a stanchion/stopper for sea-fastening of deck cargo
Introduction Stanchions – a familiar term for mariners and ship designers. What are Stanchions? A stanchion is generally a vertical pipe or beam which is used to support some structural item or provide support rails on the deck. In ships, the most common type of...
Hydrogen as an alternative fuel for ships to reduce emissions
,This article first appeared in the Feb 2019 edition of Marine Engineers Review. It is being reproduced with minor edits here for the readers of TheNavalArch's blog. Introduction The world is on facing a grave environmental challenge with an increase in carbon...
Global wave statistical analysis and its use in deepwater operations
Why do we need wave analysis? For the design of offshore operations such as installation and transport of offshore structures, as well as lifecycle design of floating and fixed structures, knowledge of extreme waves as well as the probability of different sea-states...
Designing bolts for a joint connection
Introduction Bolts are very commonly used fastening items and used in a variety of configurations. In this article, we will explore in-depth the design of a bolt used in connecting two members at a joint (bolted joint). We'll see what properties of the bolt are...
The why and how of designing a lifting beam
Lifting beams are universally applied gear used widely in various types of lifting operations, onshore and offshore. In this article, we will explore the design of a basic lifting beam and see what design checks are needed to establish the suitability of the beam for...
Draft Surveys: Methodology, Calculations, and common errors
Introduction Marine transport is the backbone of the global trade and reasonably can be considered to be the artery of the global manufacturing supply chain, as more than four fifths of the world merchandise trade by volume is carried by sea. Undoubtfully, the...
Designing a clip/dog plate for seafastening
Introduction In an earlier article, we saw how to design stoppers for seafastening. Stoppers are items that are used to contain the translation movements (longitudinal and transverse directions) of a cargo on the deck/hold of a vessel. That brings us to the question –...
The Bulbous Bow – types, characteristics, and effects
This is Part 2 of the two-part series on Bulbous Bows. For Part 1, click here By Tamal Mukherjee, *This article originally appeared in May 2019 edition of Marine Engineers Review (India), the Journal of Institute of Marine Engineers India. It is being...
Marine Propeller and Shafting Alignment – Part 2
Gap & Sag Alignment Gap and Sag Alignment is carried out to bring the engine to its final position, in case of directly coupled installations, and to bring the gear box to its final position in case of installations with reduction boxes. The figure below indicates...
Marine Propeller Shafting and Shafting Alignment – Part 1
*****This article first appeared in July 2018 edition of Marine Engineers' Review (MER), India. We're reproducing it for the readers of our blog***** Abstract: Since 2013, Shaft Alignment Practice has undergone a change, with developments of Analysis tools. At the...
Using Class Rules to assess the Longitudinal Strength requirement of Barges
Introduction The longitudinal strength of a vessel is integral to its evaluation for a given purpose. To get an introduction to the topic, please refer to our other article https://thenavalarch.com/longitudinal-strength-ships-introduction/ In this article, we’ll see...
The four important factors for a ship’s windage area calculations
Introduction The windage area of a vessel or offshore structure is the area that is exposed directly to the wind. As is obvious, this is the area of all items above the waterline. This will include Part of the hull/offshore structure above the waterline...
How soil vertical stiffness parameters affect buried pipelines
Introduction Pipe soil interaction is a critical subject of analysis in the field of the offshore industry. A pipe once buried in the seabed is usually in equilibrium with the surrounding soil. There are however various forces which are still in action even if the...
Three simple but useful calculations when towing a Vessel
In this article, we will explore three simple but useful calculations that can be used for towing operations. They are: Towline Stiffness Propeller race Towing bridle force DNV-RP-H1o3, Modelling and Analysis of Marine Operations, FEBRUARY 2014 has been referenced...
The why and how of freeboard calculation of a ship
Introduction Freeboard is a common term used in vessel operations. Freeboard is the smallest vertical distance between the waterline and the freeboard deck (generally the upper deck) along the length of the vessel. The term ‘smallest’ is of significance, as the height...
Calculating the maximum stacking height of pipes
Introduction Pipes (or linepipes or joints) are used for multiple purposes and locations in the maritime/offshore industry. Onshore and offshore pipelines are used for transportation of fluids on land, over and underwater. Pipes are fabricated in an onshore facility...
Designing a spreader beam for lifting
Spreader beams are universally applied gear which is widely used in various types of lifting operations, onshore and offshore. In this article, we will explore the design of a basic spreader beam and see what design checks are needed to establish the suitability of a...
Protecting the seabed pipelines against destabilization: Identifying and qualifying the risk
The Philosophy Cable hydrodynamic stability is one of the most fundamental design topics which are addressed by cable installation engineers. In its simplest form, a simple force balance approach may be considered to ensure that the cable is not displacing...
Safe Towing: Calculating a towline’s catenary and sag
Introduction Towlines connect a tug to the vessel being towed and are defined by multiple characteristics like Weight, Diameter, and Stiffness. The tension in the towline during the towing operation is not static but keeps varying with the distance between the tug and...
Designing the lashings of deck cargo using IMO CSS
Introduction More than 70% of the earth is covered by water, which makes shipping historically the easiest and cheapest way of connecting manufactures and customers across the globe and can be reasonably considered to be the artery of the global economy....
Using MS Excel to evaluate the Stability of existing Barges
Barges are the simplest, and yet most widely used of marine vehicles. They are used for a variety of purposes ranging from carrying cargo in bulk or liquid, to even carrying passengers for short inland cruises. Barges are mostly towed by another barge called a tug,...
The importance of ULS (Ultimate Longitudinal Strength) and how to assess it for a damaged hull
by Alessandro La Ferlita, Naval Architect Ultimate hull girder strength represents the maximum capacity, of the hull girder beyond the structure fails. In fact, if the vertical bending moment applied overcomes a certain maximum value, the ship can collapse (Figure 1)...
How to calculate the strength of Midship Section of a Ship
The mid-ship section of a ship is a defining structural drawing of the vessel. It represents the most critical structural parameter of the vessel – its global strength. To assess how much of the bending moment (hog and sag) the vessel can tolerate, it is important to...
How to use empirical formulas to estimate the resistance of a Ship
How to use empirical formulas to estimate the resistance of a Ship Resistance estimation holds immense importance in the design stage of a vessel. Based on the results of the resistance estimation of a vessel, the selection of the right propulsion system is done....
Designing the berth mooring of your vessel with this simple yet effective method
A vessel at berth experiences much lower forces compared to a vessel in the open sea due to the milder environment, but it still requires a mooring configuration suited to the forces it experiences, and also suitable for the type of berthing configuration adopted. The...
Bulbous Bows – History and Design
by Bijit Sarkar, Naval Architect Introduction The eternal search of a naval architect – a perfect bow. Sadly, it never exists. Different bow forms are good for different types, sizes of vessels and seaways. What does a naval architect want out of the bow he designs?...
Understanding how buoys affect the catenary of a mooring line
What is a mooring line? Mooring lines generally comprise ropes, wires, chains or combination of wire and chain used to keep ships, offshore platforms and other floating vessels in position. It connects the structure either to the seabed using an anchor or the quay...
Calculating forces on a ship’s deck cargo – a simplified approach
A cylindrical deck cargo (Source: Wikimedia) Introduction A ship’s deck is used to transport many different types of cargo – from containers to large structures like cranes or heavy modules of an offshore production plant. During transport, the ship suffers from...
Designing a pad-eye: little items with big intricacies
Pad-eyes are one of the smallest and most universally used structural items in the maritime and Oil & Gas industry. They are used for a variety of purposes too: from a simple seafastening of a cargo to deck of a vessel, to complicated lifting operations involving...
Vessel with Stern on Quay: A simplified method for mooring design
A vessel at berth experiences much lower forces compared to a vessel in the open sea due to the milder environment, but it still requires a mooring configuration suitable to the forces it experiences, and also suitable for the type of berthing configuration adopted....
Cathodic Protection – Ships, Offshore Platforms, FPSO’s and Pipelines: a comparison
Cathodic protection of a structure is an exercise which requires close study of the structure on which it is going to be implemented. The type and quantity of cathodic protection by anodes will depend upon multiple factors: the Geometry of the Structure, the...
Role of a naval architect – a walkthrough (Part – 1)
This is the first in a series of articles on 'Role of a Naval Architect' by Mr Bijit Sarkar, a Naval Architect with 35+ years of experience in ship design and shipbuilding. I would define a naval architect as one who has the ability to greet the client as he/she walks...
The bulbous bow – why some ships have it and others don’t
By Tamal Mukherjee, This is the Part 1 of a two part article on the Bulbous Bow. Part 2 can be accessed here *This article originally appeared in May 2019 edition of Marine Engineers Review (India), the Journal of Institute of Marine Engineers India. It is being...
Mitigating risks during subsea cable installation
Over the last 20 years, the interest in offshore wind power generation has increased substantially. Offshore Wind Energy currently provides only 0.3% of world power generation, but the potential is really vast. In the next 20 years the offshore wind industry is set to...
A simple method of selecting the right anchor for mooring a tanker/gas carrier
Anchoring is a fundamental and sensitive operation for a vessel. When a vessel is at anchor, it swings to align itself along the direction of the dominant environment. The anchor is supposed to hold the vessel in varying environmental conditions depending on where the...
Designing a simple 4-point lashing system for a Deck Cargo
Introduction Lashing of a deck cargo on a ship involves different means and mechanisms to secure the cargo to the deck of the ship. This ‘securing’ is important to contain the movement of the cargo in view of the ship motions during the transportation. The simplest...
Calculating a Ship’s Design MBL using OCIMF MEG-4
In Part 1 of this article, we saw a step by step guide to calculate the Environmental forces on a vessel based on “Standard” environmental criteria defined in Section 3 of OCIMF Mooring Equipment Guidelines Fourth Edition (MEG-4) in order to determine the ship’s...
Selecting the right equipment for towing operations – Emergency Towing
In Part 1 of the article, we discussed the regular towing arrangements and how to select the towing gear for the same. In this part, we will discuss the components of the emergency towing arrangement and how to select them. The purpose of emergency towing equipment is...
Preliminary Rigging Arrangement Design OF 4 point, Single Hook Lifts for Non-Specialists
by Michael Harwood, PE, PMP Overview Lifting by crane is a basic construction operation that dates back to at least Sixth Century BC (ancient Greece for example) and the lifting operation itself dates back much further. It is a very common operation in present-day...
Autonomous ships of the future
Automation is in good servant but a bad master!By Dr L R Chari, ex-Executive Director of Shipping Corporation of India (SCI)*This article originally appeared in June 2018 edition of Marine Engineers Review (India), the Journal of Institute of Marine...
The digital transformation of the maritime domain
(This article originally appeared in June 2018 edition of Marine Engineers Review, Vol 12, Issue 7, Journal of The Institute of Marine Engineers (India), and is being reproduced here for readers of TheNavalArch's blog)The maritime domain is gradually...
Selecting the right gear for towing operations – Part 1
Towing operations seem pretty straightforward – we just need to connect the vessel to be towed to the right sized tug and get started! However, a simple exercise of digging deeper will reveal critical items that we need to take care of. If we start thinking about the...
Removing Human Error in Ship Performance Analysis
Introduction Shipping is the most dominant means of transport that facilitate global trade. Over 90% of world trade is done by ships[1]. Fuel onboard ships, commonly referred to as "bunkers", has become the largest cost item of a ship's Operational Expenses (OPEX),...
OCIMF MEG-4 and Mooring Design of your vessels – Part I
Part 1 – Environment and Environmental forcesThe OCIMF (Oil Companies International Marine Forum) has come out with the latest edition of mooring Equipment Guidelines (MEG) – Rev 4. This revision incorporates significant changes and updates over the MEG-3,...
Equipment Numeral Calculation for a Ship – a Guide
Intriguing as it sounds, Equipment Number (or Equipment Numeral) throws a plethora of questions when heard for the first time. Is it something which tells the number of equipment on a ship, or is it a catalog which assigns specific number to the equipment...
CFD in the marine industry: today and tomorrow
In the world of advancing digital technology, it important to identify all the best ways to apply it to the extremely complex task of designing a ship. Riding the wave of the rapid progress of High Performance Computing, Computational Fluid Dynamics (CFD)...
Marine Lifting – Engineering and Planning
Ever since the offshore industry has expanded to deeper waters, one topic of broad and current interest, that has dominated the industry, is the weight of topsides lifted offshore. Installation contractors advertise engineering feats accomplished by...
Transportation Analysis for deck cargo – complete breakdown
Introduction In the simplest terms, Transportation Analysis is the complete design and engineering which goes behind making a transportation operation successful. In this post we'll talk about transportation of project cargo over deck. Such cargo can be equipment,...
Loadout Ramps – design and analysis of the simplest flat plate ramp
Loadouts are a complicated exercise and require intricate engineering calculations to ensure success of the operation. Right from selecting the suitable vessel with adequate ballasting capability, to performing ballasting and stability calculations,...
Why the bollard pull calculation method for a barge won’t work for a ship
In my working with the marine transportation industry for more than a decade now, I have come across many different calculations for required bollard pull for both barges and ships. The principles of the calculation are same, whether it is a ship, a barge...
STEEL COILS LOADING – ITS CHALLENGES AND WAYS TO OVERCOME
STEEL COILS LOADING – ITS CHALLENGES AND WAYS TO OVERCOME by Mr. Spiros Malliaroudakis (Founder & Managing Director, S.A. Malliaroudakis Maritime (UK) Ltd) The loads derived from steel coils loading are very concentrated, leading to higher stresses...
Naval architecture, new challenges and a new horizon
Naval architecture, new challenges and a new horizon by Lim Soon Heng, BE, PE, FSSS, FIMarEST Founder President, Society of FLOATING SOLUTIONS (Singapore) Civilization has arrived at a point of inflexion triggered by global warming and rising sea levels....
Mooring System Design and Analysis
Mooring System Design and Analysis by Rahul Kanotra, Consultant Naval Architect As the offshore industry moves towards greater technological advancements, one thing that has plagued the engineers is the “plug and play” computer programs or software. I am not against...
Cargo Stoppers – why they are critical and how to design them
Stoppers and their critical role in seafastening of cargo Introduction A cargo transported on the deck of a ship is subject to many forces. These forces comprise of the inertial forces due to the ship motions – the three translations and three rotations – and the...
Are you chartering a tug bigger than necessary for your Barge?
Barges are one of the most frequently used means for transporting deck cargo of different shape, size and weight. While some barges are self-propelled, the majority is towed by another vessel called a ‘Tug’. Once an owner or charterer...
Fendering – an Introduction
In this two part article we will talk about Fendering, which is one of the basic but critical operations related to a ship. Fendering is, basically, protecting the ship’s sides from contact with another body (which can be another ship, jetty or quay wall). It can also...
Loadouts – An introduction
Image source: Flickr Loadout Operations - an Introduction Loadout is a term oft heard of in the marine/offshore industry parlance. Loadout is generally referred to the operation of transferring a Cargo or a Structure from the place of fabrication to a sea-borne...
Introduction to Pipe Transportation – Part 3 (Engineering)
Introduction to Pipe Transportation - EngineeringIn Part 1 we learnt about pipes, while in Part 2 we learnt about Planning and Scheduling of pipe transport operations. In this part, we will learn about Engineering.Phase 3 – Engineering.Engineering for pipe...
Introduction to Pipe Transportation – Part 2 (Planning & Scheduling)
In Part 1, we looked at the properties of pipes. In this section, we will be looking at the Planning & Scheduling of a pipe transportation operation (see below, Phase 1 & 2) SECTION 2: PLANNING, SCHEDULING, AND ENGINEERING FOR A PIPE TRANSPORT PROJECT Source:...
Pipe Transportation – An Introduction (Part 1)
(To read Part 2, click here) This is the first part in the 3-part series on Pipe Transportation. In this part we will discuss about pipes and their properties. In this article, we will talk about the transportation of pipes on ships. Pipes are needed for various...
Ship Corrosion – Cathodic Protection and Sacrificial Anodes
CATHODIC PROTECTION ON SHIPS – SACRIFICIAL ANODES Image Source: pixabay SECTION 1 – INTRODUCTION Due to the environment in which they operate, ships are among the structures most exposed to environmental corrosion. The sea water is a very corrosive environment...
Longitudinal Strength of Ships – an Introduction
LONGITUDINAL STRENGTH OF SHIPS – A GUIDE Source: http://worldwideflood.com Talking about strength of a ship, the picture that comes to mind is that of a ship being subject to rough weather of the sea, and trying her best not to crack or capsize. A ship with sufficient...
Bollard Pull Calculations – an Introduction (Part II)
Bollard Pull Calculations for Towing Operations Part II - Finding out the maximum feasible tow speed (To read Part I, please click here) Introduction This is Part - II of the two part article on Bollard Pull calculations. In the Part I we saw how to calculate the...
Bollard Pull Calculations – an Introduction (Part I)
Bollard Pull calculation is one of the most frequent calculations performed in marine towing operations. Towing operations involve the pulling of a vessel (it can be a barge, ship or an offshore structure) using another vessel (usually a tug).
