Saturday, August 29, 2009

Delineating ship lines-plan and drawing human figures

All naval architects have lives other than designing ships or calculating resistance, propulsion and stability of marine vehicles. For me, my pastime activities include drawing human figures, jogging and photography. After reading complicated hydrostatic properties of ships in some naval architecture textbooks during the day, at night I prefer to make sketches of beautiful girl, birds, scenery, and color it using Derwent watercolour pencils that I bought several years ago in Gramedia bookstore of Surabaya city.

Drawing lines plan of a ship is different from drawing the body of a beautiful girl.  Drawing human figure does not need a lot of technical calculation only more practices that are needed. Ship's lines plan can only be delineated after principal dimensions have been determined from preliminary design calculation. In the past, naval architects had to draw and fair ship lines manually. The body-plan of ships or boats has to be streamlined to minimize the resistance while moving on the water. Now, computer software such as Delftship and Maxsurf is specially made to help ship designer for doing such kind of job with better accuracy.
As I have previously said in the first paragraph of this post, I am very fond of drawing human bodies especially girls. Naturally girls' figure is streamline but to draw them we don't need any complicated calculations. It is the skill level of the artist's hand that determines the quality of the drawing. Usually, before painting or coloring, I make the sketch of the girl using Staedler 2B pencil. I will draw the macro drawing first, i.e. drawing the major parts of the body such as head, arms, body, and legs. After correcting the proportions of the body, I will continue the drawing by adding details to eyes, nose, lips, fingers, and clothing ornaments. The sketch of the drawing has to be perfect before the coloring is done.
Because I use Derwent watercolour pencils to colour the girl, I have to do it little by little. After applying first layer of colour, I have to let it dry for one day and continue the coloring again. So, the finished painting takes one week to accomplish. I can do that in one day but I will get drawing results that looks rough. by Charles Roring Read: Boat building and Living tradition of the Mentawai Tribe ; Sailing Across the North Pole with Boat to the New World and How to estimate ship's length for a new design

Tuesday, August 25, 2009

Passenger Ships of PELNI Lines the safety and service

Modern passenger ships have been integrated into Indonesian maritime industry since they were first introduced into Indonesian waters in 1980s. After the ro-pax ferry KMPTampomas accident in late January 1981, PELNI - the largest passenger lines in Indonesia began to modernize its fleet of passenger ships to prevent such disaster from occurring again.
KM Nggapulu was entering Port of Manokwari
In the middle of 1980s, PELNI received new passenger ships from Meyer Werft (shipyard) of Germany into its fleet to serve major ports in Indonesian islands. Some of them are KM Kambuna, KM Kerinci, KM Umsini, and KM Rinjani. KM stands for Kapal Motor or Motor Ship. These ships each could carry around 3,000 people but during the high seasons they double the capacity to between 4,000 and 5,000 passengers given that the summer load waterline did not exceed the minimum freeboard stipulated by IMO or Classification Rules.
All the additional passengers were deck ones. This is still practiced by PELNI lines at the moment. Although it is a dangerous practice during bad weather, as long as it still adheres to the stipulated freeboard, PELNI considers that the additional number of passengers will not bring the ship into the risk of sinking.
It is not clear whether PELNI also increases the number of life jackets, boats and rafts to protect the passengers at sea. In addition, the additional passengers that PELNI ships have to carry during school holiday, Idul Fitri, Christmas and New Year seasons make the sea voyages are not comfortable.
More passengers mean more rooms, water, and food the ships should provide. In fact, passengers often complain that they run out of water to shower. The gangways and decks look dirty too during high season voyages.
Although waste streams produced by passenger ships are smaller compared to the whole amount produced by the whole world shipping industry, when not properly treated and discharged into the sea, they really threaten the marine environment.
The provisioning of modern passenger ships has restored passengers' confidence over PELNI's service. Feeling that such investment in high cost European made ships was worthy due to the profits and better safety standards the ships gave to the company, PELNI ordered more ships in 1990s.
Today there are nearly 30 passenger ships PELNI has in its fleet. It is a state owned shipping company that is intended not only to transport people but also to connect the whole territory of Indonesian islands as one undivided country. So, it is the government's policy to provide ships that support the development of national integrity of Indonesia and also to serve passengers from moving from one island to another.
When transatlantic passenger ship-liners have long been replaced by airplanes, it is amazing to see that PELNI is the only company that runs true passenger liners in fast schedules transporting a lot of people every year. 

Saturday, August 22, 2009

Boat building and Living tradition of the Mentawai Tribe

In today's post, I am going to tell a story about boat building tradition maintained by one of the tribes in Mentawai. Mentawai is a group of islands located west of Sumatra, Indonesia. Boat or canoe is made from log in the middle of the jungle. The boat will be used for transporting people and food. There are not calculations of displacement or stability involved in this boat building. The builders only used their intuition and tradition.
The boat is not constructed from pieces of wood but it is dug out from large log. The length of the boat can be up to seven or eight meters. One thing that is interesting here is that the Mentawai tribe performs unique ritual in every step of boat or canoe building. After making the boat, they will have to push it to the river which is quite far from the place where they built the boat. The inauguration of the boat was carried out with simple ritual and prayers.
Although the boat is very simple in design, its draft is well predicted if I should not say well calculated. Even experienced naval architects will admire their way of making boat from the log. Last week, TV5 Monde Asie, a global satellite French TV aired a program about the daily life of the Mentawai tribe. This indigenous people are still living in traditional ways - no electricity or even basic health care facilities provided by the government. They still have to go out for hunting boars using bow and arrows and machetes. I forgot the name of the producers of this documentary film. I highly respect and appreciate their works in making this film.
What I like the most from the TV program is the rituals the tribe performed to heal sick person. A shaman and some men killed a boar and used it in the healing ritual. They performed a dance until they were trance. I wish I could understand the whole story of the natural dance unfortunately the program was in French.
The rapid deforestation or the conversion of tropical rainforest in Mentawai islands into massive mono-culture palm plantation is a major threat to the survivability of this indigenous people. They had to face investors who are only greedy of making money from the lucrative CPO or bio-fuel commodity.
The concern of this indigenous Mentawai people should be ours too. As more and more trees are cut to make way for palm plantation, questions should be raised whether the bio-fuel industry is legitimate if large areas of forest should be jeopardized. 

Friday, August 21, 2009

Sailing Across the North Pole with Boat to the New World

On this article, I am not going to talk about ship but a little about a legendary boat. There was a legend in Ireland which says that the Irish monks were the first European to land on the New World. Around one thousand years ago, an Irish boat sailed across the north-pole waters to find a new land. They used a boat whose hull was not made of wood but animal skin. I read the story about this expedition on an article of National Geographic Magazine. I forgot the year of its publication. I wonder how a small boat crossed the Atlantic. It was too dangerous to sail from Ireland to the New World with a boat that was not seaworthy. All naval architects would agree with this.
There were some Irishmen who re-built similar boat and used it to cross the icy ocean and landed on Canadian territory. They proved that the Irish monks could have been the first Europeans to find the New World. I saw that the cover picture about the story was very interesting and I drew it on a small paper. The boat had sails decorated with red-cross. I used Derwent watercolor pencils to make the drawing. It took three days to finish the drawing of the boat.

Wednesday, August 19, 2009

How to estimate ship’s length for a new design

by Charles Roring

After performing the calculation for estimating the ship's displacement, deadweight, as well as the lightweight of a new design, the next step a naval architect will usually calculate is the length. There are many books about ship design that deal with the estimation of ship's length. I recommend Merchant Ship Design by Munro-Smith, Ship Design and Construction published by SNAME, or two other books that I will mention below.

If the new ship is going to operate on international shipping, it might pass through Panama Canal which only allows the maximum length to be 289.56 m. Length of the ship can be estimated using Sneekluth's formula. Please, see page 2 of Ship Design for Efficiency and Economy, written by H. Sneekluth and V. Bertram.


Sneekluth Formula

LPP = Length Between Perpendiculars (meters)

Δ = ship's displacement (ton)

V = speed (knots)

Fn = Froude number

The length of the new ship can also be calculated using cube root format which is presented on page 5 of Ship Design and Performance for Masters and Mates as follows:

Cube root format


p= density of sea water = 1.025 metric tons/ m3

CB = block coefficient

CD = deadweight coefficient

Although I only present two formulas here, actually, there are still other formulas for estimating the length of a new ship. If you are now designing a new ship, I suggest that you design its lines plan using delftship. Also read: How to calculate displacement of newly designed ship and Ship rudder

Tuesday, August 18, 2009

How to calculate displacement of newly designed ship

Naval architects when designing a ship often face many difficulties in determining the displacement due to the lack of data for the weights of hull components, propulsion machinery, wood and outfit, equipment and etc.
Displacement of a ship is the volume of water that it displaces when floating at sea or river. The volume is calculated in cubic meter. If it is multiplied with the sea water density (1.025 metric ton/cubic meter) then we can get the displacement which equals to the ship weight.

On page 4 of Ship Design and Performance for Masters and Mates, Dr. C.B. Barrass gave a simple formula for calculating the displacement of newly designed ships. The formula is called deadweight coefficient.
CD = dwt/W
The following table is the typical deadweight coefficient for various types of merchant ships

DWT Coefficients of Merchant Ships

The deadweight coefficient varies from one ship to another depending on its type and is calculated up to SLWL or Summer Load Water Line. It is the condition where a ship is fully loaded.

Worked Example:
For a new design, the deadweight of the ship is determined to be 12,000 metric tons. Information from previously built similar ships suggests CD to be 0.6. Estimate or calculate the fully loaded displacement (W) and the lightweight of the new ship:

W = dwt/CD
W = 12,000/ 0.6 = 20,000 metric tons.
Lwt = displacement - deadweight
= W - dwt
= 20,000 - 12,000 = 8,000 metric tons This is only for preliminary design calculation.
If we see on the table above, the ship is a container ship.

When the lines-plan of a ship is available, the calculation of her displacement can be done by integrating the areas of waterlines usually from WL 0 to Summer Load Waterline. Similar calculation of ship displacement can also be carried out by integrating the areas of stations from the stern to the forward end of the ship. Hydrostatic and Bonjean curves provide a lot of information which sailors or ship designers can use to analyze the hydrostatic and hydrodinamic properties of the ship.

Recommended Book
There is a good book for naval architects or anybody who is interested in learning about this topic. Its title is Ship Design: Methodologies of Preliminary Design, written by Apostolos Papanikolaou.
You could order this book to learn more about the determination of hull form, the main dimensions and the basic characteristics of different types of ships. I highly recommend this book for you to read it.

Related post
Ship's Displacement Calculation Using Simpson's Rules

Thursday, August 13, 2009

Passsion of a ship toy in child's imagination

boat-cruise-ship.jpgMany times when we go to the beach, we can see parents accompany their children swimming. But among the crowded swimmers, there are some who are more interested in playing with boat toys. The passion of the sea and the ship in little boy's mind bring his imagination tens of years in the future where he dreams of building a ship or being the captain of a ship sailing across the ocean.

I made a painting about such scene using watercolour pencil depicting how a father accompanies his son playing a toy of a sailing boat. Right behind them a few miles away, there is a cruise ship moving.

The message from this painting is that we must not ignore the passion of a little boy playing with his boat. We have to encourage him, if necessary, by taking him to a sea voyage aboard a real cruise ship or passenger ship where he can see the real ship.

Perhaps, the boy has another dream. Being somebody who can build a ship or boat. He might not know the name of such profession as being a naval architect is not a common job anybody sees in every day life. There are not many schools that provide such study program. So, what we must do is to guide the boy in pursuing his passion on the sea and the ship through a positive way. by Charles Roring also read: Is traveling with cruise ship still an attractive adventure? and The Speed of Ship and Propeller Pitch

Saturday, August 8, 2009

Ship rudder

Every cruise ship and cargo vessel needs at least one rudder. This is usually installed behind a propeller which is located at the stern of the ship or boat. Although we cannot see it, the functions of rudder are vital for the maneuverability of the ship. A rudder, according to page 87 of Ship Design and Performance for masters and mates, is needed
1. To keep the ship on a straight line, from Port 'A' to Port 'B.' In other words, to have good course keeping properties.
2. To turn the ship in a small turning circle diameter. In other words, to have good turning characteristics, say in confined waters.
The dimensions of a rudder are determined by the coefficient K according to the type of ship, the length between perpendiculars, and the loaded draft of the ship.

The following formula is used by naval architects to calculate the rudder area of ship. AR = K x LBP x d (m2)
If a ship is a fast one, generally, its K value is lower. So, the rudder of high speed marine vehicles is smaller than conventional speed marine vehicles with the same displacement. Below is the coefficient K for several merchant ships. The above formula can also be used for ships with twin screw propellers.
We have to remember that rudder is not the only equipment that is available for ship's maneuvering. Most cruise ships and cargo vessels have bow thrusters to help them turning to the right or to the left.
Usually the height of a rudder is 1.75 its length. Please, see the following illustration as a guidance for naval architects when designing ship's rudder.

It is important to note that the rudder size should not be too large. If it is larger than appropriate, it will be an additional resistance for the ship itself as well as decreasing the course keeping properties of the ship.Rudder is turned by hydraulic mechanism that has been installed above it inside the stern part of the ship's hull. by Charles Roring Also read: Are cruise ships safe for the marine environment?

Saturday, August 1, 2009

Ship Design Books

Also read:
by Charles Roring

The study of naval architecture is related to the theory of ship that is aimed at designing, building and repairing of ships and other floating structures. There are many books that discuss about ship designs. Some of them that I used to read are Ship Design and Construction, Ship Design and Performance for Masters and Mates, and Ship Design for Efficiency and Economy.

I downloaded the Ship Design and Construction book from yesterday. It is a very thick book written by a group of authorities in the field of naval architecture. Unfortunately, the quality of this e-book is so bad. So I recommend that those who want to study or read the book buy or order it directly from the Society of Naval Architect and Marine Engineers (SNAME). Amazon online bookstore also sells the book, some are used books that are offered in cheaper price.


The book of Ship Design and Construction discusses various aspects that are related to ship design such as mission analysis and basic design, general arrangement, load line assignment, tonnage measurement, analysis and design of principal hull structure, hull materials and welding, hull outfit and fittings, cargo handing, ship maneuvering, navigation and motion control and many other subjects.

If you don't have the background in naval architecture, I suggest that before reading this book, you have to read basic ship theory volume I and II or the Principles of Naval Architecture. These books provide you with strong theoretical foundation before dealing with more complicated aspects of ship design.

Naval Architecture is different from Land or House Architecture. Ships are moving structures. So, there are other aspects such as stability of ships and resistance and propulsion that need to be studied. Also read: Are cruise ships safe for the marine environment? and Is traveling with cruise ship still an attractive adventure? ; Cruise ship and passenger ship