Thanks for all the great comments, guys. Very instructive!

Bryan, what are the implications of running those numbers for improving the design?

My friend Richard says he’s 5 ft 10 in and 190 pounds. He intended to use this kayak primarily for flat water paddling in Puget Sound without a sprayskirt. So speed and comfort are priorities. Good rough water handling is desirable but rolling is not at all important. The idea was not to build a replica, but something inspired by the traditional kayaks, Type 4 in Harvery’s book.

My initial thought was that trying to build a skin−on−frame kayak from a CAD drawing might be difficult because the wood won’t necessarily bend the way you want it to, and the sheer is largely determined by the angle of the gunwales, although I guess by gluing extra wood to the ends you can shape the sheer any way you want.

I agree it looks like it would have problems with weathercocking. Richard says that the cockpit placement is based on averages from Harvey’s book. But then I’ve heard that Greenland kayaks were designed to weathercock on for hunting reasons, or is that not true?

So it’s back to the drawing board. Richard says he plans to add more deadrise. I suggested adding more rocker. He has totally scrapped the D−shaped coaming idea. I think the idea there was to make it easy to build.

Andrew

: I quickly modeled it in Delftship and here are the goods assuming an 18'
: kayak.

: Length over all 17.996 ft
: Beam over all 1.865 ft

: Displaced volume 4.475 ft3
: Length on waterline 16.073 ft
: Displacement 0.125 tons
: Beam on waterline 1.751 ft
: Total length of submerged body 16.073 ft
: Waterplane area 17.411 ft^2
: Total beam of submerged body 1.751 ft
: Waterplane area 17.411 ft^2
: Block coefficient 0.4326
: Waterplane coefficient 0.6186
: Prismatic coefficient 0.5402
: Waterplane center of floatation 8.807 ft
: Vert. prismatic coefficient 0.6993
: Entrance angle 9.359 Degr.
: Wetted surface area 23.157 ft^2
: Transverse moment of inertia 2.889 ft^4
: Longitudinal center of buoyancy 8.700 ft
: Longitudinal moment of inertia 208.33 ft^4
: Longitudinal center of buoyancy -1.343 %
: Vertical center of buoyancy 0.231 ft

: Midship section area 0.515 ft^2
: Transverse metacentric height 0.877 ft
: Midship coefficient 0.8008
: Longitudinal metacentric height 46.789 ft

: Lateral area 5.039 ft^2
: Longitudinal center of effort 8.683 ft
: Vertical center of effort 0.205 ft

: I need to know his design goals and why not just build a replica?