vair = 10;
A = 60;
rhoair = 1.168;

i = -100:100;
vb = i * 0.1;

p_prop = 50 * abs(vb).*vb.^2 + vb.*A.*(vair -(vair+vb)/3+vb).*abs(vair+vb+(vair+vb)/3)*rhoair/2;
p_turb = A * (vair + vb).^3*rhoair*8/27;

hold off;
plot(vb, p_turb*0.5, 'g')
hold on; 
plot(vb, p_turb, 'r')
plot(vb, p_prop, 'k');
% ---- try to set this up for forces instead of power ...
vair = 10;
A = 60;
rhoair = 1.168;

i = -100:100;
vb = i * 0.1;

% Boat has drag plus wind forces...
f_boat = 50 * vb.*abs(vb) + A.*(vair -(vair+vb)/3+vb).*abs(vair+vb+(vair+vb)/3)*rhoair/2;
p_turb = A * (vair + vb).^3*rhoair*8/27;
f_prop = p_turb./ vb;

hold off;
plot(vb, f_boat*0.5, 'g')
hold on; 
plot(vb, f_boat, 'r')
plot(vb, f_prop, 'k');
