Using the text() command?
clear t
Vkts = [120,110,100,90,80,70,60,50];
Vms = Vkts/1.944;
Hdata=0:0.15:0.6;
figure(1)
hold on
for i=1:numel(Hdata)
H_m=Hdata(i);
eta = -((2*860*9.81)./(1.1549*Vms.^2*14.82))*((H_m)/(0.471*3));
eta_deg = eta*(180/pi);
plot(Vms,eta_deg)
t(i)=text( Vms(4),eta_deg(4),"H_m = " +H_m);
end
hold off
xlim([26 62])
ylim([-40 1])
grid on
grid minor
str={t.String};
leg=legend(str{:},'Location','Southeast');
