Proa sketches in Rhino

Grasshopper hulls, Apr 16, 2014

Grasshopper ("GH") is a Rhino plugin, a graphical programming tool that generates and manipulates 3D parametric models. I wrote a GH script to draw a proa hull and deck using an algorithm I developed over the years. Instead of manually redrawing a complete hull, numeric sliders are used to move pre-defined control points that generate curves that generate the hull and deck surfaces. Hydrostatics including displacement and prismatic coefficient (Cp) are shown.

As an expediency, the windward and safety amas are copies of the main hull, offset and scaled separately in X, Y and Z directions. The absurdly extreme sheer shown in a few pics show the range of this "dial a boat" approach enabled by encoding the algorithm as a GH script.


Spring Equinox, March, 2016

Winter Solstice, December, 2015

Grasshopper Salon/Coach, July, 2015

Leeward Salon, Single Entrance, August 27, 2014

Coach Dimensions... August, 2014

interior - below beam... Apr 5, 2014

wide coach roof... Mar 31, 2014

coach/pilot roof shapes... Mar 26, 2014

safety ama musings... Mar 24, 2014

old and new... Mar 16, 2014

Model Notes history...

These sketches of a 70' Pacific proa were done in the process of learning Rhino CAD. Nothing is final. The basic parameters of the vessel were defined decades ago, the "saftey ama" to leeward is new, and there is still a lot of room for style (like cars!).

This safety ama is one foot off the water at rest, is engaged at 10 degrees heel and gets max. displacement (55% of total) at 20 degrees heel angle. At this size, that extra volume is useful for accommodations.

more Grasshopper coding




A pair of 70' Pacific proas, one with an AC62 wing sail at 100% size (103' tall),
the other wing scaled to ~60% height (61.5' tall, ~70' off the water), ~35% to 40% surface area of the AC62 wing, lower center of effort.