Do not confuse this type of hull with one that simply has pipe chines. True radius-chine hulls have a radius of between 24 and 36 inches (600 and 900 mm). The radius-chine hull has many benefits, including all of those attributed to a round-bilge metal hull. The fact is that the radius-chine hull is one of the easiest hull forms to build in metal. This ease of construction applies from making the frames right through to the final plating.

   All true radius-chine hulls are designed, faired, and lofted in the computer, so you’ll have accurate full-size patterns. Naturally, it’s most important to have accurate patterns from which to make your frames, and computer lofting is the best way to achieve this end. As the radius sections are all of the same radius, it’s only the amount of arc around the curve that will vary. This means that you won’t need to transfer all of the radius curves to your loft floor. Transfer only the straight frame sections. Make sure that the ends of these lines are clearly defined. Use a check mark to give a clear definition to the ends. Next, simply cut the straight lengths of framing and place them in position. Now, cut the exact lengths of curved frame material that have been pre-bent to the correct radius.

   You can either bend the radius-frame material yourself, or have it bent by an outside metal shop. Assuming that you farm out this work, we recommend that you have the radius-frame sections, stem bar, and lengths of plate all bent to the correct radius section at the same time (see Radius-Chine Hulls in Chapter 8, Plating Your Hull). The  techniques used for assembling the frames of your radius-chine hull are virtually the same as those used for the other hull forms.