Understanding of operational and environmental loads is necessary for fatigue design of tidal turbines. A von Kármán spectral method and a Synthetic Eddy Method are analysed for prediction of unsteady loads on a horizontal axis turbine. The blade load spectrum by the von Kármán method is in reasonable agreement with existing experimental measurements for frequencies less than the fourth harmonic of the rotor frequency but over-predicts at higher frequencies. The Synthetic Eddy Method over-predicts at low frequencies but under-predicts at higher frequencies. However, both methods provide reasonable prediction of the damage equivalent load at the blade passing frequency. This approach is used to evaluate damage equivalent loads due to in-wake and in-array operation. It is shown that the tip-speed-ratio of each turbine in the array can be selected to standardize damage equivalent load across the turbines and, for the particular turbine specification considered, this also increases power slightly compared to an array with all turbines operating at the same point.