The ornamental design for a decanterbase, as shown and described.
FIG. 1 is a top-front-left perspective view of a decanter base showing my new design;
FIG. 2 is a bottom-rear-right perspective view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a right elevation view thereof;
FIG. 8 is a left elevation view thereof;
FIG. 9 is a top-front-left perspective view thereof, showing in a condition of use; and,
FIG. 10 is a top-rear-right perspective view thereof, showing in a condition of use.
The broken lines showing of an arm connector in FIGS. 1, 3-5, and 7-10 and the broken lines showing of base handles in FIGS. 1-4 and 6-10 depict portions of the decanter base that form no part of the claimed design. The broken lines showing of a base arm and a decanter in FIG. 9-10 are included for the purpose of showing environmental structure and form no part of the claimed design.