how to properly use 'solve' function properly?

hi, i have the next code: %%%%%%%%

syms P1 Cv CLb deadrise_angle

f1 = 'CLb = P1 - 0.0065*deadrise_angle*P1^0.6';

deadrise_angle = deg2rad(16);

breadth = 5.4;

ship_weight = 40.1*1000;

water_density = 1025;

g = 9.8;

Vknt = 20:5:45;

V = Vknt(1)*0.5144;

Cv = V/sqrt(g*breadth);

CLb = ship_weight/(0.5*water_density*V^2*breadth^2);

CLo = subs(solve(f1,P1)); %%%%%%%%%%%

after executing the last comand im gettin the next notification:

*Warning: The solutions are parametrized by the symbols: z1 = RootOf(z^5 - (13*deadrise_angle*z^3)/2000 - CLb, z)*** and it gives me the solution: CLo = z1^5

where does this z1 came from? what am i doing wrong?

thanks for your help .....