F-19 NMR spectra are simulated for blue phase I of FPHG( St(1.5)*Ap (1.5)) based on a model of a double-twisted substructure inside cylinders that form a body-centred cubic lattice. A kinetic matrix is included to describe jump processes over quarter pitch lengths. Though the lines in the NMR spectra are broad and featureless, changes in the widths and positions with temperature are well described by the blue phase model structure. The spectra in the chiral nematic N* phase are also simulated. Dynamics in the BP I are found to be slower than in the N* phase.