Preliminary Design
The preliminary design of a yacht is my main hobby - particularly since it involves the most creativity in the engineering process. There are three main entities in the process including:
- Generating preliminary lines
- Performing initial structural calculations
- Making generic performance estimates
Lines Creation
The preliminary lines of a ship come from two sources. The first is through the principal characteristics of similar vessels. The second is from a generic mathematical description of a hull. Principal characteristics of hulls can often be found through magazines or reviews of production vessels. They can also be found through racing information. Because the PHRF rating provides a means to compare the racing speed of a vessel to its basic parameters, the PHRF system is useful to categorize a yacht. I have found and compiled a PHRF Spreadsheet which gives the principal characteristics of almost every rated yacht. For information on ship lines, please visit my Ship Geometry Primer
The processing of these numbers may be done in a variety of ways. One method is to perform a regression of the numbers and choose a metric to apply to new designs. My Parametric Lines Page has information on this technique as well as an excel spreadsheet which produces a generic table of offsets.
Finally, if hull information were to be described in a database format, then semi-automated design could be feasable. My new project is to form a database of hulls in XML format. The advantage of XML is that it is a simple text file which can be read and utilized in many platforms including Java, C++, Excel. Furthermore, the database may be used across all operating systems and is easily stored on the web. In fact, all of these webpages are XML files which are processed on-demand by my server to turn them into html. XML is very powerful, but I am still experimenting with the data layout. Please contact me for any questions, information, or advice.
Structural Calculations
The simplist structural design includes the scantling method. The advantage of this rule is that it can quickly process the neccessary strength of a hull in a reliable fasion. My Scantling Page provides much more information.
Performance Analysis
The resistance of a hull form can be analyzed quickly and reliably through a regression of previously recorded data. Although a tad outdated, the Delft systematic yacht series has been the best way to quickly estimate the resistance of sailing craft. One program, PCSail utilizes this series and has a convenient user interface through Excel. I analyzed PCSail in my research on the Mk II Navy 44 STC while an undergraduate. The PCSail review may be found here.
Similarly, I have built my own Delft spreadsheet for use in conjunction with my parametric lines program (above). It is a work still in progress.
Sketches
Some of my initial yacht sketches will be shown on a page here (in the future!)