Maxsurf News Feb 2005

In this issue...

Maxsurf_Automation
Hydromax
Stability_criteria_updates
Hullspeed
Seakeeper
Workshop
Link_to_ShipConstructor
User_Profile_-_Strategic_Marine

Maxsurf Version 11.0 Released

We are pleased to announce the release of version 11 of Maxsurf. Our program of enhancements and additions is continuing at a rapid pace. We will be sending Maxsurf version 11 to all members of our Maxsurf subscription program over the coming weeks.

Maxsurf Automation

Every so often something comes along that genuinely changes the way we work. It happened with the adoption of graphical user interfaces and the introduction of AutoCAD in the 1980’s. Since then improvements in Naval Architecture software have been incremental rather than revolutionary. We think, and hope you will agree, that the Maxsurf Automation Interface included with version 11 of Maxsurf will provide a new and dramatic change to the way we perform hull design and analysis. The Maxsurf Automation Interface uses Microsoft’s Component Object Model (COM) to allow Maxsurf to be controlled from an external application such as Microsoft Word, Microsoft Excel or AutoCAD.

In the past all design modification and analysis has had to be performed interactively by the user within the Maxsurf program. The Maxsurf Automation Interface now allows design and analysis to be controlled from other programs, opening up a wide range of options to the designer. The tool used to achieve this is typically Microsoft’s VBA (Visual Basic for Applications) macro scripting system. Microsoft has adopted VBA as the standard method of automating repetitive tasks within Microsoft Office and as such it is used by many naval architects to write macros in Excel or AutoCAD.

For example, if a designer wished to create a systematic series of hull shapes it used to be necessary to use Excel to perform the transformation of the control point networks, then copy and paste the control point positions into the Maxsurf control points window. Each individual hull in the series would then be saved and possibly have its hull shape manually exported to an IGES file for further analysis. With the Maxsurf Automation Interface these functions can be performed via a macro in Excel, with Maxsurf performing the tasks as a background application.

For designers wishing to optimise hull shapes using external CFD analysis, the Maxsurf Automation Interface can be used within an optimisation shell such as modeFrontier or iSight to automatically manipulate hull shape parameters. Using the automation interface it is possible to modify control points individually or to modify the design as a whole with the Parametric Transformation function, allowing an infinite variety of hull shape variations to be created.

Included with Maxsurf version 11 is a complete Maxsurf Automation manual which describes the interface in detail. To get Maxsurf users started we have also included a range of sample VBA macros to give an idea of what is possible. The sample code is intended to show how to perform different tasks using the automation interface and can easily be modified to perform more elaborate functions.

We have tried to cover a wide range of different functions in the samples provided, however the scope of possible functions that can be created using the automation interface is huge. We fully expect to be surprised by the innovative applications created using the Maxsurf Automation Interface.

Hydromax

A new analysis has been added to Hydromax 11 – floodable length. For specific criteria, the floodable length analysis calculates the longitudinal distribution of maximum length of compartment that can be flooded (with the vessel still passing the criteria). Results are presented as the length of compartment plotted (or tabulated) against the longitudinal position of the compartment centre.

Traditionally floodable length is assessed against the margin line immersion criterion; Hydromax also allows you to include maximum angle of trim and minimum longitudinal and transverse GM as additional criteria, and the margin line immersion criterion can be substituted for deck edge immersion. This allows considerable flexibility when calculating the vessel’s floodable length.

The floodable length may be computed for a range of displacements and compartment permeabilities. As with all of the Hydromax analysis methods there is full visual feedback during the analysis; you can see the different flooded compartments being tested. Drawing the vessel as the analysis progresses provides instant visual confirmation that the required analysis is being performed and that the user has entered the correct analysis parameters.

Stability criteria updates

Several new heeling arm parent criteria have been added to Hydromax. This brings the total number of GZ-based, parent criteria to 51. These criteria cover a very broad range of stability criteria calculated from analysis of the vessel’s GZ curve. The new criteria provide the facility to derive a heeling arm from specified properties of the GZ curve, such as the value of GZ at a certain heel angle and the ratio of areas under the heeling arm and under the GZ curve between specified limits. This facilitates the evaluation of criteria such as the IMO HSC Code Annex 6 – hydrofoil capsizing moment criterion.

Criteria for a number of additional stability codes are now included in the default criteria library. These include the French Sécurité Maritime criteria.

Hullspeed

Some useful features have been added to Hullspeed in this release. It is now possible to plot graphs of the various resistance components in coefficient form. Also the theoretical resistance prediction method has been improved by incorporating some of the work described in: Tuck, Lazauskas and Scullen, Sea pattern evaluation, Part 1 Report: Primary code and test results (Surface vessels) http://www.cyberiad.net/library/pdf/tls99.pdf. These modifications have improved both the reliability and speed of the resistance predictions.

Seakeeper

The conformal mapping capability in Seakeeper has been improved by allowing conformal mappings of up to 15 terms. (In previous versions the conformal mappings were limited to a three-term Lewis mapping.) The increase in mapping terms can lead to a better match between the mapped and actual hull sections.

Workshop

Workshop now includes a comprehensive library of marine stiffener sections and appropriate cutouts. These include both rolled and extruded shapes covering typical sections used in steel displacement vessels as well as high-speed aluminium craft.

Link to ShipConstructor

The link from Workshop to ShipConstructor has been further enhanced with the version 11 release. This is as a result of the growing popularity of linking Workshop's parametric, initial structural design capability with ShipConstructor's AutoCAD based detailing functions. The result is fast, iterative refinement of the structural definition in the early stages, followed by accurate, 3D modelling and data management for final design and production.

User Profile - Strategic Marine 

The Henderson precinct just south of Fremantle in Western Australia, has become a significant centre for shipbuilding. In the heart of Henderson sits Strategic Marine, a successful builder of crew and patrol boats and one of the original aluminium shipbuilders in Australia. Established in 1984, Strategic Marine has delivered over 150 vessels to a range of clients in Australia, South East Asia and the Pacific region. Most recently they have used their WA location as an ideal base to service the oil and gas industry and a range of Navy and Coast Guard authorities.

Since 1994, Strategic Marine has used the Maxsurf range of software to improve the efficiency of their design and construction processes. Strategic Marine also collaborates closely with external design company, Southerly Designs for their new design work. This type of cooperation between the shipyard and design company is commonly seen in this industry.

Southerly Designs has been a Maxsurf user since 1986. They use Maxsurf for initial design, Hullspeed for resistance prediction, Hydromax for compartmentation and stability checks and Workshop for stringer runs, frame cutouts and plate development. The design is delivered to Strategic Marine in both the Maxsurf program file formats and as detailed construction drawings.

The shipyard has its own engineering and naval architecture department to do design and production checks. Strategic Marine uses the Maxsurf programs to support these core engineering activities. They analyse the model in Hydromax and check the consequences of minor changes during construction. The stability criteria and reporting functions in Hydromax are used by Strategic Marine to produce stability booklets from inclining experiment data.

Maxsurf provides a real benefit to Strategic Marine in two ways. First, it allows the shipyard to design and engineer less complex projects independent of external design companies. Second, the Maxsurf programs support contract negotiations as Maxsurf and Hydromax can be used to quickly estimate the feasibility of, for example, a change in the length, tank volume or engine position in an existing design.

A recent example of a successful project by Southerly Designs and Strategic Marine is the design and construction of 50 patrol vessels for the Singapore Police Coast Guard. Strategic Marine recently started a new production facility in Singapore, where currently two 40 m crew boats with a top speed of 25 knots are under construction. At their own yard in Henderson, the construction of 25 in-house designed landing barges with a top speed of 39 knots is well under way.

More information on Strategic Marine can be found at www.strategicmarine.com