This puzzle is based on a few different games. The French game "L'Attaque", E. I. Horseman's 1890 game "Baslinda" or the Russian game "Морской Бой". But the most important one is the picture above. By using the following information you should be able to obtain the coordinates you're hunting for.
X1, X7, A5, A6, A7, A10, A16, A19, A20, A21, A22, A23, A24, A25, Y3, Y4
W1, W3, B12, B13, B15, B16, B19, B25, A3, A4
V1, V3, C7, C10, C11, C12, C14, C19, C21, C22, C23, C25, B9, B10
U1, U3, D7, D9, D10, D12, D13, D14, D15, D17, D19, D21, D22, D23, D25, C4, C5
T1, T7, E7, E11, E13, E19, E21, E22, E23, E25, D4, D5
S1, S2, F13, F16, F19, F25, E4, E5
R9, R10, G5, G6, G7, G9, G11, G13, G15, G17, G19, G20, G21, G22, G23, G24, G25, F9, F11
Y1, Y2, H13, H15, G3, G4
Q1, Q3, I5, I7, I8, I9, I10, I11, I13, I15, I17, I18, I20, I22, I24, H16, H17
P1, P3, J10, J13, J14, J15, J16. J17, J18, J19, J22, J24, I3, I4
O1, O3, K16, K19, K20, K23, K25, J6, J8
N1, N3, L11, L13, L16, L19, L21, L22, L25, K10, K13
M2, M5, M9, M10, M12, M16, M20, M23, M25, L6, L10
L2, L5, N8, N10, N11, N13, N15, N16, N17, N19, N20, N22, M6, M7
K3, K7, O9, O10, O12, O16, O18, O19, O21, O23, O25, N4, N5
J1, J5, P10, P11, P12, P13, P16, P17, P18, P19, P20, P21, P23, O7, O8
I1, I2, Q7, Q8, Q9, Q12, Q17, Q18, Q19, Q20, Q21, Q22, Q24, P6, P8
R15, R17, R21, R22, R25, Q4, Q6
G1, G2, S5, S6, S7, S9, S10, S13, S14, S16, S17, S19, S21, S22, S23, S24, S25, R13, R14
F1, F7, T21, T22, T23, S3, S4
E1, E3, U7, U9, U10, U11, U12, U17, U18, U19, U20, U21, U23, U24, U25, T10, T17
D1, D3, V7, V9, V11, V13, V14, V15, V17, V19, V21, V22, V25, U4, U5
C1, C3, W7, W9, W10, W15, W17, W18, W19, W20, W22, W25, V4, V5
B1, B7, X11, X12, X16, X17, X19, X22, X25, W4, W5
A1, A2, Y5, Y6, Y7, Y9, Y16, Y17, Y19, Y22, Y23, Y24, Y25, X9, X10
You can validate your puzzle solution with certitude.