Demonstration of modern means of ship production by means of the example of straking and nesting 1

Abstract

Straking means the subdivision of large areas of uniform scantling into smaller pieces of obtainable size. This paper develops a general purpose algorithm for generating the plate pieces which can be cut from standard size plates ordered from a steel mill. The algorithm uses contract plans information and generates, as a final result, fabrication data.

The algorithm is subject to various constraints, such as:

1. Avoiding the placing of seams or butts too close to various interfering members on bulkheads, decks, etc.

2. Avoiding the placement of butts or seams on openings in an arbitrary orientation.

The criterion of optimality used in the algorithm is minimum overall cost (production, planning and assembly) which is expressed in terms of:

1. Minimizing the number of different plate sizes ordered;

2. Minimizing the amount of scrap;

3. Minimizing the amount of welding.

A unique method of automatic nesting is also described. The straking part of the algorithm has been programmed for a digital computer and tests show that the results save time, increase accuracy and reduce cost.