mark williamson design

ferry design philosophy

In the last five years much new technology has evolved in the design of aluminium car ferries around the world. In developing a series of high speed passenger ferries, High Speed Light Craft’s designers have applied this new technology to achieve a series of designs which are more efficient, lighter and provide excellent sea keeping.

Semi-Swath Hullform
The semi-swath hullform provides the right balance of low resistance and good sea keeping. This hullform was developed from the Lock Crowther hulls Precision Marine first built in the mid 1980’s. The hull was most successfully used in the Austal 40m design which was first built in the late 80’s. In the last few years much development work has been done on the semi-swath hullform in Australia (at Austal where Mark Williamson was Senior Naval Architect) and in Europe (at SSPA’s towing basin for Austal, Danyards and Finyards). This work was specifically for car ferries but still holds true for passenger ferry hulls which are operating at higher froude numbers.

HSLC has recently carried out a series of tank testing at the Australian Maritime College in Tasmania which validates the results for these high froude number designs. The end result of this development work can be seen in the hullform of High Speed Light Craft designs.

Prop Tunnel
- Minimise Shaft Angle (2.5 degrees)
- Provides Lift Aft
- Minimises Transom Area

Bulbous Bow
- Excellent flow into hull
- Provides negative lift forward, hence
acts as an efficient motion damper
- Maximises effective waterline length

Controllable Pitch Propellers
In recent years waterjets have been the conventional choice for passenger ferries. Waterjets work very well for a “standard 40m” design but it does not necessarily work as well for other sized vessels. High Speed Light Craft offer controllable pitch propellers as the prefered option on its 34m, 36m, 43m and 50m designs for the following reasons:

- Optimal efficiency for all operational speeds
- Higher QPC compared to waterjets
at design speed
- Greater manoeuvreability
- Less expensive

Weight Minimisation

Finite Element Analysis
Finite Element Analysis of hull and superstructure was carried out to minimise the weight of the vessel while maintaining structural integrity to the highest standards. The finite element method allows the structure to be analysed as a whole instead of being broken down into individual components (frames, girders, etc) resulting in an optimised structure. FE is now the standard way of designing the structure of vessels over 50m, where classification societies insist on the most rigorous standards. High Speed Light Craft’s designs are possibly the only vessels of this size where finite element analysis has been used to make vessels lighter and hence faster and more comfortable.

Construction Technique’s
High Speed Light Craft designs incorporate various construction techniques in the design stage in order to minimise the weight and fabrication time. These techniques include maximising the use of extrusions, a fully developed hullform where all transverse frames and longitudinal girders are computer faired and lofted before being plasma cut. Judicial use of composites in various components such as wheelhouse, fairing pieces and selected parts of the hull.
Layout
In all designs attention has been paid to vessel layout, taking into consideration passenger comfort, functionality and weight. For the smaller designs it can be shown that a single deck passenger layout provides the optimum layout.

Optimised weight distribution
While it is most important to minimise the weight of the vessel it is also important where the weight is situated. By keeping the centre of mass as close as practical to the centre of gravity results in better motions and hence better sea keeping. In practical terms this will mean fewer people getting sea sick. This has been achieved by centrally locating the engine room for all designs apart from the 39m. This also has the added advantage of minimising the amount of cable and piping in the various systems.

Midship Section

Mark Williamson Design

48 Sweetgum St, Ashmore Qld 4214, Australia

Ph: (617) 5597 3521 Fax: (617) 5597 3529

E-Mail: info@mwdesign.net.au