The shape of the hull in the forefoot area is affected by several features of the hull including stem angle, forefoot profile shape (e.g. tightness of forefoot), bow flare, and others. Although you can experiment with these features in the sailboat hull assistant to see if you are able to achieve the desired forefoot shape, interactive editing (and perhaps insertion) of control points is likely the approach needed. The Orca3D hull assistants are intended as a means to create a starting point for a new hull model, but direct manipulation of the surface to get the final shape is expected.
When interactively manipulating the surface shape via control point editing keep in mind (a) that more than just local movements of control points be necessary, shifting of control point rows/columns may also be necessary and (b) if movement of existing control points does not allow you to create the shape you want, this implies that you may not have enough control in the current net, and insertion of additional control points may be required.
Below is a sequence of figures illustrating a process for getting the desired forefoot shape.
Initially I started off with a default sailboat assistant hull. I’ve cut diagonals at -30, -20, -10, 0 (i.e. a waterline), 10, 20, and 30 degrees.
Reorienting that column by “canting” it so that it provides control that is more normal (i.e. perpendicular) to the surface allows me to get rid of some of the hollow as shown below. However, I found that even after doing this I still did not have enough control to get the shape I wanted.
Below is a zoomed in plan view with curvature graph on. Note the hollow in the sections.
Below I’ve also turned on the control points so you can see the default arrangement in the bow. Note how the first green column of control points aft of the stem is oriented more or less in a station plane. In this particular case it does not provide the optimal control needed to shape the fore foot area as desired.
Reorienting that column by “canting” it so that it provides control that is more normal (i.e. perpendicular) to the surface allows me to get rid of some of the hollow as shown below. However, I found that even after doing this I still did not have enough control to get the shape I wanted.
Below I’ve inserted another column midway between the canted column and the next column back (Edit>Control Points>Insert Control Point) to gain additional control. This had the immediate effect of removing the hollow but also gave more control where it is needed so that I could make further shape adjustments if desired.
In a separate exercise, I created a hull from the Orca3D sailboat assistant where I modified the stem rake to achieve a more plum bow as well as the forefoot tightness and flare angles to try to achieve a reasonable compromise in forefoot shape. Below is the result. Note that I was able to achieve convex diagonals in the bow. This may not be possible for the parameters you are trying to achieve, but the direct manipulation using control point editing and insertion should still allow you to achieve the desired shape.
