19.01.2020
THE SAFE USE OF ABRASIVE WHEELS (VIDEO)

It is one of the oldest tools on Earth – from the huge machine on a factory field to the hand-held portable – the abrasive wheel’s greatest strength is and always has been its many uses. But do not be fooled as, used wrong way, it can also be very dangerous. This video sets out how to use both portable and bench-mounted abrasive wheels correctly and safely – above all, at sea.

It shows you how to choose, test, mount and use typical wheels and also addresses the international legislation governing their use. The mounting of any abrasive wheel is a task for trained and authorized personnel only. At sea, the majority of wheels are to be fitted on portable machines that are used by the crew members for the routing maintenance. At the other end of the scale, the workshop’s grinding bench is a far more specialized tool…

Note that this video is to supplement an excellent training booklet also released by Videotel and we do recommend to use both of these training resources as a set in order to get the maximum benefit and get better understanding of the dangers commonly associated with the use of the abrasive wheels on board, and how to do your work safely and avoid any issues. Note that the safety remains the priority art all times.

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19.01.2020
SHIP COLLISION RISK — AN IDENTIFICATION AND EVALUATION OF IMPORTANT FACTORS IN COLLISIONS WITH OFFSHORE INSTALLATIONS

Normally, the risks associated offshore would include, in the first turn, colliding with the offshore structure, and this risk is deservedly considered a dominating one and requiring closest attention. The main subject of this paper originates in a real need for the non-stop update and continuous review of the models developed for the assessment of this risk. The collision risk is normally governed by those actions that are taken by the crew of the vessel.

These actions depend on the different factors, among which there are both human and organizational ones, all quite difficult to measure. That is why the main emphasis has been made on the organization on board vessel, with the objective to provide a proper identification and assessment of the causes as well as the major underlying factors contributing to the collision of the vessel with the offshore installation.

To do this, the hierarchical model is applied, which implies the assessment of the covered components by the experts through interviews. The results gathered as a result of those interviews, are subsequently combined with the data obtained from the review of the relevant publications and only then the contributing factors are determined.

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19.01.2020
RIGID FINITE ELEMENT METHOD IN ANALYSIS OF DYNAMICS OF OFFSHORE STRUCTURES

The content of this publication prepared by the group of leading experts is intended to describe toe newly introduced methods applied to model the machine dynamics used in today’s offshore industry. Subject methods are normally based on the rigid FEM (i.e. finite element method) – this method is utilized when addressing the link deformations. In addition, they are also based on the homogeneous transformations – in turn, this one would be applicable to the dynamics of the multi-body system.

The authors of this book provide a good introduction to both methods so that the readers can have a clear idea of the associated principles. The models that are selected to model the above mentioned dynamics are subsequently verified through the special FEM-based software. Some of the additional calculation methods are also applied.

The math models of the offshore machines, for example the BOP gantry crane, or the machinery used for laying pipes, have been included by the authors to better illustrate the theory. Additionally, selected numerical operation simulations have also been provided. The publication will of particular interest to the designers of the various offshore facilities.

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19.01.2020
WELDING ENGINEERING — AN INTRODUCTION

This publication is in a very wide use in the various industries, including ship building, construction and repair. The volume is intended to provide readers with a good and thorough intro to the most important areas of contemporary welding engineering. The topics included in this book have been explained in a really simple and clear manner and the main accent was made by the author to the essential engineering matters.

The book features a remarkably comprehensive coverage of the different topics considered important. It was prepared as a good reference book to be used by the students; however, it will definitely be equally useful to the professional engineers. While it was not designed to be used as a handbook, it provides all basic information they may need.

The publication has gained worldwide popularity and not only among welding engineering students but also among the representatives of different areas, considering the fact that nowadays welding is applied virtually everywhere and having a good understanding of the welding concepts is a real prerequisite to the good handling of any design or construction activity and shall be possessed by any engineer, specialist and technician.

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18.01.2020
Considerations Affecting Freeboard

General

The minimum freeboard that can be assigned to a vessel is that derived from the regulations depending upon the dimensions and characteristics of the vessel. The actual maximum operating draft permitted may coincide with minimum freeboard or it may be set by other federal regulations developed as a result of U. S. law or by international agreements such as the subdivision regulations in the 1973 Oil Pollution Convention, the IMCO Chemical Code or Gas Code.

Within the load line regulations the minimum freeboard may be affected by ship geometry, hull structure or stability. In no case can a freeboard less than the minimum geometric freeboard be assigned even though the scantlings of the vessel are heavier than required for the draft and the stability in excess of that required by an Administration for the intended freeboard.

Freeboard Tables

The tables issued for freeboard are based upon a comparison with a rule vessel having a standard sheer, length-to-depth ratio, block coefficient and reserve buoyancy. Adjustments are made for variations from the standard ship and there are different tables for different types of vessels.

Strength of Hull

The regulations assume that the strength of the vessel is satisfactory for the draft corresponding to the freeboard assigned. Considerations Affecting Freeboard - 2Ships which comply with the highest standards of a classification society recognized by the Administration are regarded as having sufficient strength for the minimum freeboards allowed under the regulations. Ships which do not comply with the highest standards of a classification society are to be assigned such increased freeboards as are determined by the assigning authority. The corresponding draft in such cases is often referred to as a scantling draft

Protection of Crew

It should be noted that while the freeboard assigned is based primarily upon reserve buoyancy, the question of a suitable height of platform for the safe working of the vessel by the crew is automatically dealt with at the same time. Protection for the crew, in the strength of houses, gangways, guard rails, life lines, and the height of working platform itself, is a very important concern of the load line regulations and specific regulations are provided for each.

 

Stability

The original International Convention on Load Lines, 1930, presumed that specific stability approval was not a concern of the regulations. At that time it was assumed that those responsible had seen to it that the "nature and stowage of the cargo, ballast, and so on, are such as to secure sufficient stability for the ship."

The present Convention (ICLL, 1966) has reversed the position of the earlier Convention by including a specific regulation worded such that stability information must be provided the master of every new vessel, "in an approved form to give him guidance as the stability of the vessel under varying conditions of service." This requirement has been interpreted quite firmly by the U. S. Coast Guard to include an inclining test for almost all U. S. commercial ships, a full stability evaluation based on the inclining, and an official stability letter issued by them as a condition necessary to issuance of the official load line certificate. Many other administrations follow a similar procedure.

Passenger Ship Subdivision

A vessel engaging in international voyages and carrying more than twelve passengers is governed by a separate regulation. Considerations Affecting Freeboard - 3Internationally, a load line is assigned and marked depending upon a subdivision and damage stability analysis of the ship under the applicable regulations of the SOLAS, 1974. Under U. S. regulations for certain ships, depending upon size or other limitations, a subdivision and damage stability examination is required if six or more passengers are carried. In no case may this subdivision load line be placed higher on a ship's side than the load line permitted under the load line regulations.

Geometry of Vessel

The minimum freeboard is designed to provide a standard of reserve buoyancy (the volume of the watertight hull above the load waterline) that has been found by experience to be satisfactory in service. This minimum freeboard is based upon the geometry of the vessel. A comparison is made of the block coefficient, the length-to-depth ratio, bow height, and the sheer of the vessel with those of a standard vessel of the same length.

Corrections are made to the basic freeboard, predicated on the length of the vessel, depending upon how these particulars vary from those of the standard vessel. Deductions are made from the freeboard depending upon the length of superstructures and the character of the closures in their end bulkheads. The resulting freeboard gives a height of working platform and a proportion of reserve buoyancy equivalent to that on vessels which have proven satisfactory in service.

Both camber and sheer play a part in clearing water rapidly from the decks, but only sheer corrections to freeboard are made depending upon the differences in sheer from the standard. Since there is no standard for camber in the 1966 Convention, no adjustment need be made.

Superstructures can contribute to reserve buoyancy and offer protection to openings in the hull at the level of the freeboard deck under certain conditions. Deductions are made from the freeboard for these special superstructures depending upon the efficiency of the protection provided for access openings in the end bulkheads.

Detached superstructures are also a consideration because there are differences in the deductions for superstructures depending upon their length and location. While the regulations do not require that a forecastle be fitted, a minimum height of the bow above the summer load water line is specified. In lieu of a forecastle the required bow height can be obtained by increasing the sheer curve of the main deck.

Openings in the Hull and SuperstructureConsiderations Affecting Freeboard - 4

A most important consideration in the assignment of freeboard is the protection of openings in the hull and superstructures, such as hatches, ventilators, air pipes, scuppers, overboard dis¬charges, and the access openings in the end bulkheads of superstructures. Standards are laid down in the regulations for these, and the assigning authority must be satisfied with their efficiency before a minimum freeboard is assigned. The safety of the vessel depends far more upon their satisfactory maintenance than in any small differences in the freeboard assigned.

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18.01.2020
HOW TO BUILD A MODEL STEAMER

Even there are quite a lot of publications available about the model steamers, apparently none of them gives clear information that is normally needed by the average newcomers to the world of ship model making. The main object of this book was to fill subject gap and provide ship modelers with the information they requires as well as give them some valuable advice.

All of the information, instructions and plans have been provided in a remarkably concise form, but they are very informative and easy to understand and follow. The modelers designing their own vessels and engines make everything themselves and would hardly need any instructions, but there are so many beginners who are willing to do the thing but hesitate to start the process because of their doubt as of their own ability.

In fact building a good steamship model is not an impossible task for anyone who is handy and patient enough to spend some time and take some pains. Do not think of this construction as of some laborious and difficult task – treat it as a pleasure instead. Follow the tips and instruction provided in the pages of this excellent volume and you will inevitably succeed in constructing a good model. Note there are four large scale designs included in the pack for the ready use.

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18.01.2020
Standard Ship

In the previous article we have touched the very basics of the shipboard load line. In order to assign a load line properly, it is necessary to compare the design to a geometric ship of the Standard form. The concept of the Standard Ship with definite geometric proportions was evolved early in the discussions for standard freeboard.

Board of Trade Standard Ship

From a historical standpoint, the 1906 Board of Trade Rules (Board of Trade, 1906) in England used a Required Reserve Buoyancy to establish desired winter freeboard for both steamers and sailing vessels. This Reserve Buoyancy referred only to the intact weathertight ship and was deemed necessary for safe seakeeping. The freeboard to be assigned was such that the percentage of the total volume of the hull above the load line was equal to that required in the table.

The required buoyancy was least for the shortest vessel, 20.4 percent at 22 m, and increased to 35.8 percent becoming maxi¬mum at a length of 183 m. The required extra buoyancy for sailing vessels was 1 percent to 2 percent higher than for steamers. However, in lieu of making a complete volumetric calculation up to the freeboard deck, the designer was permitted to use certain tables of winter freeboard provided by the Board of Trade based upon a standard length to depth ratio (L/D) of 12.

Freeboard reductions of a very small order were allowed for summer weather. On the other hand, an arbitrary addition of 50 mm in winter time for the Mid North Atlantic area was required.

In addition to the regular reserve buoyancy due to the basic freeboard amidships, the regulations also prescribed a standard sheer curve adding buoyancy at the bow and stern. This buoyancy was considered effective in promoting the seakeeping properties of ships in heavy weather.

The freeboard for a given length and depth also varied slightly according to the "coefficient of fineness" which was defined (Board of Trade, 1906) as the ratio of all under freeboard deck volume to the product of L x R x D.

ICLL 1930 Standard Ship

The Standard Ship of the 1930 Convention had:

• a L/D ratio equal to 15;

• a fineness coefficient equal to 0.68;

• a table of freeboards increasing with length of ship;

• a standard sheer; • a standard camber of the main deck;

• a minimum percentage length of superstructure;

• a required forecastle for tankers.

In the International Convention on Load Lines 1930, the coefficient of fineness was specially defined only in English units as follows:

Standard Ship - 2

where d1 figure was the mean molded draft at 85 percent of the molded depth. Subsequently, in the ICLL, 1966 the title Coefficient of Fineness was dropped and the correction is now called the Block Coefficient correction.

ICLL 1966 Standard Ship

The Standard Ship of the 1966 Convention (ICLL, 1966) is similar to the 1930 standard ship except for the camber requirement which was dropped and the forecastle requirement which was removed in favor of a minimum bow height for all manned vessels. The fineness coefficient was redefined as the block coefficient, as previously mentioned.

Some types of ships less than 100 m in length are expected to have a weathertight superstructure on at least 36 percent of their length which will add buoyancy and form a righting moment to resist extreme rolling. These ship types with superstructures covering less than 35 percent of the length must accept added freeboard.

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18.01.2020
NAVAL ARCHITECTURE

Another piece of classics here. The old yet useful volume on naval architecture written by the former professor of naval architecture and marine engineering of the MIT, standing for the Massachusetts Institute of technology. The intention of the publication was to provide in a connected and maximum possible consistent manner the theoretical essentials of the naval architecture.

The author tried to stick to this approach, making the presentation of the material more direct and simple, particularly for such topics as the ship stability, ship propulsion, local and overall strength, displacement and many others. First of all, the author gave a clear statement of the computing rules and also included an informative instruction on the mechanical and graphical integration. Then, the text moves to the detailed explanation of the ship displacement and everything related to the stability of the ship, since this is considered one of the most important areas.

All fundamental information and commonly used computational methods have been covered in detail. Going through the contents of the book we can definitely say that the author managed to compile all the basics of the naval architecture in a single volume which would be equally useful to the students of naval architecture and to the practicing shipbuilders and ship designers.

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