New 61m Cat Design from Sedlmayer Associates Released

A spectacular new 61 meter luxury catamaran design has been completed by Sedlmayer Associates, naval architects based in Southport, Queensland, Australia. Rhino and Orca3D were instrumental in the design process. Albert Sedlmayer describes the design and the design process:

SEDLMAYER ASSOCIATES PTY LTD developed SPECTRUM 61 from Hand-sketched pencil ideas straight to Rhin03D, without a 2D draughting stage in between. It has been much more efficient and more accurate this way, with no nasty surprises later on.


Very early on SPECTRUM 61 established her unique character and made it quite clear which features she wanted and which she rejected, so we developed a family of structural details to suit, to avoid the stress concentrations usually associated with these sharp features.

Below the chine/spray-rail we used Orca3D’s dynamic lines function to quickly establish fairness and optimal transition of water-flow between strakes.


Above the waterline nearly all predominant surfaces are segments of pure geometric sphere, cylinder and flat primitives, as her character demanded.

The hull topsides, chine to sheer, are derived from a spherical segment comprising only three master stations over her 61 metres with three vertices each, and only the bow vertices pulled into the hull centreline. This assures a planar sheer. The resulting maindeck surface is then a saddle-shape with minimal vertices and arc sections.


Orca3D was used extensively right from the first hull sketch, to monitor and optimise displacement, hull coefficients and areas curves.

We used Orca3D’s Holtrop analysis to calculate resistance and determine engine power and optimum speed range. We have found excellent correlation between Orca3D’s Holtrop results, tank testing and deployment feedback of our ships in service, and are very confident in these results.


We assign weights to fitout and general arrangement components from early on using Orca3D weight and cost features. These are refined and updated as the design progresses.


We assign weights to all structure components as they are developed in Rhino, and thereby keep extremely accurate running weight and CG control. Temporary PC weights are assigned to parts still to be determined, and updated during the design process.

A. Sedlmayer
Sedlmayer Associates Pty. Ltd.