Bezier 12.5 Study Plans
The Bezier 12.5 has been Redesigned

From a "Proof of Concept' point of view the 'Bezier 12.5 prototype built was aa success.  My issue with the Prototype build is that it is a Type Two hull configuration.  I have concluded that combining a Bezier True Round surface with a Developable surface serves no real purpose.  I know see that the Design and Building procedures are more laborious than they need to be.

I believe that a single surface Type Three Bezier design has so many advantages over the other configurations that I will be redesigning the Type Two version of the 'Bezier 12.5' to a Type three single surface version of itself.  While this is the primary change the following are the other changes to the Bezier 12.5: 

All Aluminum Construction.

The Fore and Aft decks are changed from 3/8" marine grade plywood to 1/8" aluminum.

The Transverse framing has been changed from 2 x 2 x 1/4" angle to 2 1/2" x 1/4" flat bar.

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 is not separately fabricated as previous.  Keel shell plating is reduced to a thickness of 0.160".

Hatch opening in fore and aft bulkheads will be replaced by larger aluminum cover plates to provide easier access to the void spaces for the installation of 18 cubic feet of spray in flotation.


Design Process Improvements:

·       A Type Three Bezier design 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.   

·       The Designer can create a hull form free of the limitation imposed by incorporating Developable Surfaces.

·       Designing the Longitudinal framing system is less problematic. There are no placement consideration as detailed in the Chapter on 'Alternate Longitudinal Placement'.


Building Process Improvements:

·       'Floating the Longitudinal' and the 'Natural Lay' of Sheetmetal as a building concept does not apply.

·       There are no Theoretical chines that complicate the construction Process. 

·       There are no Developable surfaces to template.

·       Single Plating Method.

·       There are No Longitudinal shell plating weld seams.

·       Overall construction is simplified.


Comparing the Versions:

In the redesign of the Bezier 12.5 from a type two to a type three design there a several features that were strictly retained:   Sheer Line, Fairbody Line, Location and shape of the Bow, Angle of the transom, Keel configuration.  Every thing in between changed to some degree. 

[Figure XLIX-XYZ] shows an overlay of 'Master Curves' Two, Three, and Four.  [Figure L-XYZ] shows the overlay of 'Master Curves' Five, six, and Transom.

 It can be seen there is little difference in hull shape between the two versions.

 There is virtually no change to the displacement of the hull.  Both version come in at 1550 pounds.  This includes a crew weight of 300 pound.  The weight of the boat therefore is 1250 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 virtually the same.



Principles Dimensions:

Construction: --- Aluminum

Length on Deck: --- 15' 9.5"

Length Waterline: --- 12' 6.0"

Beam on Deck: --- 6' 7.25"

Beam at Waterline: --- 5' 1"

Draft: --- 2' 6.5"

Displacement: --- 1250 lbs

Ballast: --- 475 lbs

Sail Area/Displacement Ratio: --- 15.3

Sail Area --- 127.7 sqft

Displacement to Length Ratio: --- 372

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