Impact of rules and regulations on design

A ship designer must satisfy not only the owner's stated requirements but also the IMO regulations and classification society rules. The first will define the type of ship and its characteristics such as size, speed and so on. The second broadly ensures that the ship will be safe and acceptable in ports throughout the world. They control such features as sub-division, stability, fire protection, pollution prevention and manning standards. The third sets out the 'engineering' rules by which the ship can be designed to meet the demands placed on it. They will reflect the properties of the materials used in construction and the loadings the ship is likely to experience in the intended service.

There are three basic forms the rules of a classification society may take:

• Prescriptive standards describing exactly what is required, reflecting that society's long experience and the gradual trends in technological development. They enable a design to be produced quickly and do not require the designer to have advanced structural design knowledge. They are not well suited to novel design configurations or to incorporating new, rapidly changing, technological developments. Because of this the performance standard approach is increasingly favoured.

• Performance standards which are flexible in that they set out aims to be achieved but leave the designer free to decide how to meet them within the overall constraints of the rules. They set standards and criteria to which the design must conform to provide the degree of safety and reliability demanded.

• The safety case approach which considers the totality of risks the ship is subject to scenarios of predictable incidents. A formal safety assessment (FSA) involves identifying hazards; assessing the risks associated with each hazard; considering alternative strategies and


making decisions so as to reduce the risks and their consequences to acceptable levels. Put another way the designer thinks what might go wrong, the consequences if it does go wrong, the implications for the design of reducing, or avoiding, the risk; making a conscious decision on how to manage the situation. Thus a designer might decide that although an event is of very low probability its repercussions are so serious that something must be done to reduce the hazard.

Although attractive in principle, FSA is an expensive approach and is likely to be used for individual projects only if they are high profile ones. It can be used, however, as the basis for developing future classification and convention requirements. One problem, particularly for radically new concepts is foreseeing what might happen and under what circumstances.

It is clear that probability theory is going to play an increasing part in design safety assessments and development. To quote two examples:

• When considering longitudinal strength the designer must assess the probability of the ship meeting various sea conditions; the need to operate or merely survive, in these conditions; the probability of the structure having various levels of built in stress and the probable state of the structure in terms of loss of plate thickness due to corrosion.

• In considering collision at sea, consideration must be given to the density of traffic in the areas in which the ship is to operate. Then there are the probabilities that the ship will be struck at a certain point along its length by a ship of a certain size and speed; that the collision will cause damage over a certain length of hull; the state of watertight doors and other openings. Then some allowance must be made for the actions of the crew in containing the incident.

Statistics are being gathered to help quantify these probabilities but many still require considerable judgement on the part of the designer.

How To Have A Perfect Boating Experience

How To Have A Perfect Boating Experience

Lets start by identifying what exactly certain boats are. Sometimes the terminology can get lost on beginners, so well look at some of the most common boats and what theyre called. These boats are exactly what the name implies. They are meant to be used for fishing. Most fishing boats are powered by outboard motors, and many also have a trolling motor mounted on the bow. Bass boats can be made of aluminium or fibreglass.

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