Bezier Chine - Pre-Fabrication

Today's Steel and aluminum boats use a longitudinal framing system, which uses closely spaced longitudinal frames that are supported by widely space transverse frames. The shell plating is supported by and welded to the longitudinal frames. Longitudinal framing serves 'Bezier Chine' design and construction well and is integral to the alignment the shell plating.

Construction Parts Groups:

The hull parts can be divided into three basic groups: Longitudinal frames, transverse frames and the shell plating. Bezier Chine design defines all these parts, for the builder, thru full size patterns and Cnc cutting files. Bezier Chine designed boat are 'Kit Boats'.

There is a great degree of versatility in Bezier Chine Designs. Depending on the construction material, your equipment, your skills and budget.

Longitudinal Frames:

Longitudinal frames can be Cnc cut, saw cut or rolled formed. Each method is fully detailed in my book 'True Round Metal Boat Building'. Below is an example of rolled formed Longitudinals

Transverse frames:

The same degree of versatility is extended to the transverse frames. Below is a representation of a sheet of full-size patterns. Below that is a completed frame assembly which was fabricated from that pattern.

True Round Shell Plating:

The Shell plating is the heart of 'Bezier Chine' design and construction. No other design method pre-engineers shell plating. Shell plating can be Cnc cut, saw cut or hand cut using plasma or oxygen-acetylene torch. Below is a typical shell pattern for the Bezier 12.5, along with a description of its parts.

  • The number "21" indicates that this pattern is the 21st from the bow.
  • The word "Sheer" at the top of the pattern indicates that this edge is the located at the Sheer Line, while "Chine Long", at the bottom, indicates the chine longitudinal.
  • On this particular pattern there are approximately 20 horizontal lines which represent the three (3) degree bend lines. A press break will be used to form this pattern to the curve of the hull along its girth.
  • The "Cross Lines" associated with the numbers 21.937 inches and 21.477 inches are reference dimensions aiding the forming process by providing the corner to corner finished dimension after all the horizontal lines have be bent at three (3) degree angles.
  • The curve line (marked Frame #7) running vertically and curved near the center of the pattern locates the intersection of shell plating with transverse Frame #7. All shell patterns with this type of line will be aligned to its corresponding transverse frame.
  • Boot Strip Lines (really marked on the other side of the pattern) indicate the painted boot stripe. The lower line of the boot strip is 1/2" above the design water line.
  • Notice the small half circles along the vertical edges of the pattern. They indicate the location on the shell plating where it crosses a longitudinal frame. They also provide a place to tack weld the shell plating to the longitudinal frames.

Pictured below is a pattern being formed in the press break. My book 'True Round Metal Boat Building' detail the entire shell plating forming process.

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