Hi Donny. I’ve modeled dozens of hulls this complex or more so. My approach is always to analyze the hull and determine how to model it with the fewest surfaces, while maintaining the original design.

In your case, I’d model the bottom as one surface from stem to stern with approximately 8 station curves. Each curve would be built of degree five and six points. These stations would extend from centerline to chine, even forward of where the chine is a knuckle. This surface would be modeled by lofting, which process creates a smooth and easily editable surface.

Next, I would draw the curves that represent the edges of the tunnel and centerline deadflat in 3-d and project them all three to the base plane. The 3-d curves will serve as “templates” in fairing the hull.

With these three curves in place, tweak control points on the hull until a projection of each of the three 2-d curves (the ones on the baseplane) to the hull is within tolerance of the original 3-d curves.

If you envision the original 3-d curves as being “locked”, you can see that iteratively projecting the 2-d curves from the base plane to the hull in the top viewport will eventually produce 3-d curves that match the original curves within tolerance.

To check how close you are, use the “crvDeviation” command. This will tell you where the trouble spot lies, indicating where you need futher tweaking of the hull surface.

Once you have a match for each of the three curves, trim the hull from centerline out to the deadflat and between the two edges of the tunnels. Fair the tunnels as separate surfaces and project the curve at the outboard edge of the deadflat in the front viewport to the center plane to form a hull at centerline curve. The deadflat is then formed with an edgeSrf, selecting the outboard edge of the deadflat and the centerline curve just created. The skeg would also be modeled separately.

Once the skeg and other appendages have been modeled, it is quite likely you will need to join all the surfaces into a closed polysurface, since a great many analysis packages depend on solids.

This process of closing the surfaces can easily be the most frustrating part, but it can’t be overlooked or shortcut, if the analysis software demands it. The only advice I can offer on this is to grit your teeth, have plenty of coffee on hand and keep at it till there are no naked edges.

One of the most satisfying experiences in creating a model such as this is when you are joining the surfaces together and, picking the last one, the model magically redraws, telling you that your model is now a closed polysurface.

These and many other techniques are available in my tutorial series, available at http://basline.com//Products.aspx.

If this all sounds too involved, rest assured, the bottom can be modeled in less than half a day.

Regards,

Cliff W Estes

BaseLine Technology

Rhino training and reseller

Independent software developer

http://www.basline.com