Proa 2018 May20a by oster on Sketchfab


Proa sketches in Rhino/Grasshopper

April/May, 2018


Questions that keep me from knowing how to finish a credible, detailed model of this 30 year old vision, despite the excellent CAD tools. I just don't have the building or engineering experience to answer them myself.

1) How tall does the 8" thick crossbeam need to be at its outboard end? Currently 16" at 28.5' from main hull center-line, where it is 37" tall.

2) How thick is the bridge deck floor? As drawn in proa_2018_Apr28a.3dm, I have 9.5" under the leeward salon seat and 8" under the windward seat (visible on the 'interior::extend to bottom' layer). This is in accordance with the 15" two-step difference expected between galley floor and salon floor.

3) What holds up the mast?

4) How thick is that "bench seat beam" (truss) to windward? It is now 19.5" high at the center, including the seat. ~24' long at its current position, ~14' to windward of main hull center-line. Long due to wide beam separation.

If allowed to follow the cut away pod/shell surface, it would be at a comfortable height for supporting winches at the center. Two concerns, though an uncovered truss structure handles both:

5) Egress - Absurd that I haven't got a clear answer for this, but it's like using the windward cockpit for a main entrance on a Chris White or Gunboat catamaran - without headroom.

Pacific Proa Design Considerations and Details

October/December, 2021

January, 2018

Spring Equinox, March, 2016

Winter Solstice, December, 2015

Grasshopper Salon/Coach, July, 2015

Windward Pilothouse, Leeward Salon, Single Entrance... August, 2014

Coach Dimensions... August, 2014

Grasshopper hulls, Apr 16, 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.

more Grasshopper coding