What makes a Ship Float - Archimedes Principle & Buoyancy

It was not without purpose that a genius was so excited as to jump out of his bathtub and run naked on the streets shouting Eureka! Infact so important was that discovery that even the floatation of the huge mass of a ship can be explained like a child’s play.

Introduction

We learnt about the center of gravity and centroid in our previous article. Now we will move a step further and see how a simple principle discovered centuries ago in a bath tub can be applied equally well to the vast oceans in perspective of floatation of a ship.

Archimedes Principle

The science of floatation is simple yet equally interesting to know and let me explain it for you in the simplest manner possible. Now you know that every body or object has got a volume which means that if that object is placed on the surface of the water, it will displace water which is equal in volume to the volume of the object immersed inside the surface of the water (let me add here that I am using the term water in context of sea and ships, otherwise this principle applies to all fluids).

The volume of water that has been displaced certainly possesses a certain amount of mass which is given by

Mass of water displaced = volume of water displaced * density of water

Ship Stability and the Center of Gravity

You must have read about the center of gravity of a body in your high school physics but do you know its importance in the context of ship stability in the vast oceans? Just read on to find out more!

Introduction

In the previous article we learnt how forces and moments could be acting on a body at a given point of time and how to find the net or resultant value of those forces or moments. In this article we will continue our study of ship stability by learning something about center of gravity, centroid and their relationship to stability of a ship floating in the sea.

Center of Gravity

When studying objects, forces and their inter-relationships we often tend to represent a body by a point for theoretical purposes of calculations relating to that body. This certainly is a convenient method of representation but we know that in actual situation there is hardly any body which is actually the size of a point, so how do we go about it?

Ship Stability for Navigating Officers & Marine Engineers

It is very interesting to see a huge mass of metal float seamlessly on the surface of the ocean but do you really know the science behind the floatation and stability of the ship in the midst of the vast ocean? If not, just read on to learn about it in a simplistic manner.

Introduction

In this topic we will cover the basic aspects about ship stability starting from the very fundamental concepts which will help you to grasp the subject matter with ease. Since it is vital to understand the concepts behind stability we will start with a discussion of the underlying principles and theories behind the exciting science of ship stability. Such an approach would have the double benefit of being simple to understand for normal readers while it will help you to prepare for your marine certification exams if you are a student in this field.

About Force, Net Force, Moments et al.

Arnold Schwarzenegger, Hollywood actor-governor of California

"Strength does not come from winning. Struggle You are the one who gave birth to strength. When you face adversity and never give up, that is strength."

Ralph Nader, U.S. Political Activist-Lawyer

"A true leader always has the vision and conviction to realize the dream. He inspires the power and energy to achieve a purpose."

Walter Bagehot, British writer-journalist (1826-1877)

"The biggest satisfaction in life is to succeed doing something that others think you are not able to do so."

Ella Wheeler Wilcox, U.S. writer-poet

"Strands of love that is not based on genuine feeling of friendship is like building a house on sand."

Types of Ships by Silhouette : Part 2

Helicopter Carrier

A Japanese Helicopter Carrier, the Hyuga, by Reann S. Mommsen, courtesy of the United States Navy and via Wiki Commons

More nations operate small carriers capable of handling only helicopters or VTOL jets than deploy full-on aircraft carriers. Many nations even don't call them aircraft carriers to avoid negative associations, an example being the Hyuga above which is called a "helicopter destroyer" by the Japanese authorities, much like Russian carriers during the Cold War were called "aircraft carrying cruisers" to avoid legal restrictions set around transiting the Bosporous region.

They are set apart from the larger full-deck carriers as well as similarly sized amphibious warfare ships because they lack a well deck (so sit lower in the water relative to amphibs) and have a superstructure that takes up relatively more deck space than true aircraft carriers. In addition, their helicopters are a dead giveaway if no fixed wing aircraft are seen as well.

 

Types of Ships by Silhouette : Part 1

All ships have a unique silhouette and this characteristic is often the best means of telling one type of ship from another. Here are some ship silhouettes that are representative of their type, as well as some pointers on how to tell ships apart. At sea such quick identification can be a big aid.

Typing Ships by Their Silhouettes

An incredible assortment of ships sail the planet's waters. Ranging in size from behemoths like aircraft carriers and supertankers to little fishing trawlers, making sure that accidents are kept to a minimum in an environment where the endless waters and unpredictable weather is no mean feat. Often the first step in deciding what course of action to take when two ships meet at sea is simply to figure out what the respective crews are dealing with. Identifying whether a ship appearing on the horizon is a fishing boat or cargo ship is key in ascertaining the proper attitude towards it - while a big cargo ship is likely to be relatively hard to maneuver and so can be expected to maintain a fairly predictable course, a smaller ship could well turn unexpectedly and pose a collision hazard.

But telling ships apart, even big from small, is not always easy at sea. Size can be deceptive, especially if distance is not clear. And at sea, with no landmarks or sizing clues to work with, it is easy to underestimate or overestimate the size of ships appearing on the horizon. In the Second World War it was not uncommon for scout ships and aircraft to report that they had spotted fleets full of huge battleships, only to later find that they'd seen a squadron of smaller destroyers.

To tell ship types apart in a reliable fashion, typing ships by silhouettes has become a common practice. Different types of vessels exhibit starkly differing physical characteristics that can be noted by the naked eye. From the shape of the deck to the pattern of the superstructure, silhouettes make it easy to tell a navy cruiser apart from a cargo ship.

Supercarriers

USS Kittyhawk Operating in Support of Operation Enduring Freedom, courtesy of the United States Army, via Wiki Commons

Supercarriers are some of the largest and most visually striking ships to behold. Only eleven of them exist, all used by the United States Navy, and all are rather easily identifiable by their flat deck profile broken up only by the aircraft that are parked around it. Fortunately for anyone at sea, these 1,000+ foot, 100,000+ ton behemoths only travel when surrounded by smaller ships and covered by jets and helicopters. Passing ships will know it is there and be guided a safe distance away in short order- no one risks damage to a supercarrier.

Mechanical Material Properties Required in Ship Construction

Even as recent as the previous century, a lot of ships were being lost at sea owning to material weaknesses. Learn about a few material properties required for a strong ship construction and the role of classification societies.

Jiddu Krishnamurti, The writer-philosopher of India

"When hearts filled with incomparable feeling called love and feel the depth, beauty, and therefore happiness; then you will realize that the world has changed. "

History of Naval Architecture: Transformation in Ship Construction

In this article we will learn as to what were the changes and modifications in the the design of the ship, that took place due to the numerous inventions and discoveries in that era.

Introduction

This was one of the various aspects that led to a change in the way ships were made. The change was gradual but was there to stay, for a long time. It was not only the wars but also the rise in the scientific inventions which gave a push to naval architecture and ship building. In this article we will see how these inventions and discoveries brought a change in the design and construction of ships and how it acted as a stepping stone for the future progression.

Role of Naval Architecture

This article intends to give a brief idea as to what naval architecture is all about. An extremely disciplined field, naval architecture is all about constructing and designing a ship in the most efficient way. Find out the important role of naval architecture in the article inside.

Role of Naval Architecture Through the Ages

Ships are one of the oldest forms of transport used by men. Over the time, their structure, functions and equipments have been subjected to constant evolution. These constant evolutions have been propelled by the ever changing patterns of world trade, the necessity of the economic alterations and the incessant advances in technology. Among these, technology has been a vital factor in providing opportunities to build larger, faster and safer ships.

Naval architecture has been an intrinsic part of the evolution of ships, which has been captivating and equally demanding at the same time. Naval architecture is a discipline that requires highest degree of discipline as well. It is demanding because there is large amount of capital investment that goes in the making of the ship and also because ship building is a risky job. Find out what role naval architecture play in ship construction.

Anatole France, Penulis Prancis (1844-1924)

"To achieve big goals, we not only need to act, but also dream, not only need to plan, but must believe."

What does a Naval Architect do?

Design and construction of a ship is not an easy task. It requires tremendous persistence and hard work. The personnel dealing with ship construction job are known as naval architects. Lets find out what this naval architects do and what is it that make their task so demanding.

Introduction

A ship is such a massive structure that it often compels us to think as to what does it takes to build such a gigantic thing. What does it take to make a ship? And more than that, who makes them? Designing a ship is not only a challenging task but also an interesting one. It requires the application of engineering principles to the ocean environment.

A visit to a ship building yard or a shipping company would answer most of your questions, but that wont help you to figure out as to what are the processes that goes behind the making. In this article, we will go through the various activities performed by the ship building personnel and briefly try to understand as to what they do.

About Naval Architecture

A naval architect has an important role in the design and manufacturing of marine vessels. They are responsible for much more than the initial design.

Naval architecture

The study of naval architecture is similar to any engineering branch. In naval architecture, the study of the design of marine vehicles such as ships and tug boats takes place.

Naval architecture is a combination of art, science, and engineering. They do different jobs in a marine vehicle industry such as the initial design of ships, trial of the design, and development and evaluation of the design.

The jobs of a naval architecture in a marine vehicle plant are given below.