This paper proposes a timing recovery tracking scheme for single-input multiple-output (SIMO) communications derived from the maximum likelihood criterion for an all-digital single carrier receiver. The timing recovery scheme proposed is able to take advantage of the spatial diversity at the receiver side, especially when a common time scaling is present over the multiple antennas. This phenomenon appears when the sampling rate at the receiver is different of its value at the transmitter or in broadband communications with moving platforms. The SIMO timing recovery tracking scheme is applied to single carrier phase-coherent modulations over records of underwater acoustic communications. The proposed method allows improving the performance of the estimation or equalization of SIMO channels in comparison with conventional timing recovery SISO schemes applied independently on each antenna.