Offshore Pile lateral load 1

Hello, I want to ask about the Reese and Matlock method of lateral load, it uses some coefficients (Ay,As,Am,Av,Ap. and By, Bs, Bm , Bv,Bp) in a formula containing the shear and moment applied to find either slope, deflection, soil reaction ,moment at a certain depth. So I am trying to use it for an offshore pile, to find the maximum deflection at top of the pile, or moment at top, basicaly under the platform directly.. So for this level for which z is negative, (above sealevel), the coefficients A and B cannot be found in the table, because we are looking for deflection above the ground, and all depth in table are positive. Is there a certain way to solve this issue. Also any help about finding the actual ultimate lateral capacity or moment of the pile to compare it with respective loading found by this method, is welcome.