It is possible to
build a round bilge steel or aluminum hull without the great time and effort, not to
mention specialized experience, required using traditional steel outbuilding methods.
There are several reasons for building a radius chine hull. Your boat will enjoy all of
the benefits of a round bilge hull including superior appearance, strength, lighter weight
and much higher resale value; all of this while maintaining the advantages of steel or
These new radius chine building techniques are
only possible with computer assisted, yacht design and computer fairing which provides the
builder with full size patterns of all the frames and the stem. Also included are full
size expanded and developed transom patterns. The secret of radius chine depends on
fairing the radius through to the bow. Many previous attempts at this type of hull form
have tried to fade out the radius before it reaches the bow. This usually results in an
unfair area up forward.
By designing the radius chine hull completely in
the computer using specially developed Yacht Design Software, it is possible to have a
totally fair round bilge steel or aluminum hull. The hull is designed as a one and one
third hull form, the computer then strikes a new centerline so the radius of the chine and
the curve where stem and bottom join equals the pre- determined chine radius. The purpose
of this article is to "walk you through" the process of building a radius chine
Assuming you have selected a suitable design,
you will have received your boat plans and full size patterns and your first job will be to
carefully study the boat plans. An hour of study can save several hours of un-fruitful labor.
Keep your full size patterns rolled up in their sealed tube until you are actually ready
to start building. Choose a dry day to lay out your patterns on a level plywood or steel
floor area which is slightly larger than the total height and width of your hull.
your patterns on to the steel or plywood using one of the several methods such as Center
punching several points and fairing in the curves with a batten or using a
dress-makers wheel to transfer the lines on to a temporary plywood floor. The steel
area can be future be easily fitted and cut from flat or T bar. The curved constant radius
sections, usually between 27" to 36" radius, can either be bent in-house or sent
to your local blacksmith or equivalent.
A word on
bending flat or T bar on edge. It is possible to get very accurate results by setting up a
hydraulic jack in a framework. This simple device will take care of bending all of the
deck beams, stem, and other similar items, so it is well worth your efforts to put this
device together at this time.