A Short History
of
'Bezier Design and Construction'


In the Beginning:

When 'Bezier Chine Design and Construction' was just a baby inside my mind, my thought process was focused on using 'Approximate Development' to improve the basic concept of 'Radius Chine' design.

At that time, I thought it best not to deviate from the Double Hard Chine hull configuration required in a 'Radius Chine' design.  Even though 'Bezier Chine' is not restricted to that hull configeration.

Therefore, my first effort using 'Approximate Development' as a construction method to form 'True Round' surfaces by a Press-brake method mimicked a 'Radius Chine' design.

While the surface between the Developable surfaces is undeniably 'True Round', I really did not feel that 'Bezier Chine Design and Construction' was presented in its best light using this hull configuration.


The Prototype - The Bezier 12.5

My next design would start the 'True Round' surface at the Sheer-Line, continue it around the turn of the chine, where the True Round surface would seamlessly flow into a developable bottom surface. 

The design itself would be Classic in styling, Curvy, Incorporate Tumblehome, and sized so that I could built Her as the 'Prototype' and 'Proof of Concept' build for 'Bezier Chine Design and Construction'. 


Coming Full Circle 

Since building the 'Bezier 12.5, I have come to the realization that combining a True Round surface with a Developable surface serves no real purpose.

I now feel, that a single surface True Round design has so many advantages over the previous configurations that I was compelled to redesigned the 'Bezier 12.5' to a single True Round version of itself.  While this is the major change, the other changes to the Prototype version of the 'Bezier 12.5' are: 

  • All Aluminum Construction. 

  • The Fore and Aft decks are changed from 3/8" marine grade plywood to 1/8" aluminum.
  • The Fore and Aft Bulkheads are changed from 3/8" marine grade plywood to 3/16" aluminum.  These bullheads become an integral part of the transverse framing system.
  • The original 3/16" bottom shell plating is replaced by 1/8" thick Bezier shell plating which now runs from Sheer to Fairbody.
  • The keel is now constructed integral to the hull.  The Keel shell plating is reduced to a thickness of 0.160".

  • Hatch opening in the Fore and Aft bulkheads will be replaced by aluminum cover plates to provide access to these void spaces for the installation of a minimum of 18 cubic feet of spray in closed cell flotation. 

What Stayed the Same:

There were several features that were strictly retained in the redesign of the Bezier 12.5 from a Double surface design to a single surface design:

  • The shape and position of the Sheer Line.
  • The shape and position of the Fairbody Line.
  • Location and shape of the Bow.
  • Position and angle of the transom.
  • Placement and configuration of the Keel.

Comparing the Hydrostatics:

  • There was virtually no change to the displacement of the hull.  Both version come in at 1,550 pounds.  This includes a crew weight of 300 pound.
  • The weight of the boat therefore is 1,250 pounds with 550 pounds being lead ballast.
  • The Longitudinal center by buoyance is 54.3% of the Design waterline and 5.880" below the Design Waterline.
  • The Vertical Center of Gravity is 1.000" above the Design Waterline. 
  • All other Initial Stability and Coefficients are effectively unchanged.

Design Process Improvements: 

  • The Bezier 12.5 is as True Round as any fiberglass Design.
  • A single True Round Bezier surfaces simplifies the Design Process significantly.   
  • There are no Theoretical chines that complicate the Design Process.  
  • Designing the Longitudinal framing system is less problematic.

Building Process Improvements:

  • Single Plating Method.
  • There are no Theoretical chines that complicate the construction process.
  • There are no Developable surfaces to template.
  • There are No Longitudinal shell plating weld seams.
  • Overall construction is simplified.

Comparing the Hull Lines:

The below images show an overlay of 'Master Curves' Two, Three, and Four,  Five, six, and Transom.   It can be seen there is little difference in hull shape between the two versions.

True Round 1
True Round 2

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