The ornamental design for a synthetic straphoist, as shown and described.
FIG. 1 is a perspective view of the synthetic strap hoist showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof;
FIG. 8 is an another perspective view thereof; and,
FIG. 9 is a reference view showing the synthetic strap hoist being in using status.
The broken lines shown in the figures are included for the purpose of illustrating portions of the synthetic strap hoist and form no part of the claimed design.