The ornamental design for a boatseatbeverageholder, as shown and described.
FIG. 1 is a perspective view illustrating a boat seat beverage holder;
FIG. 2 is a perspective view illustrating the boat seat beverage holder in an alternative configuration;
FIG. 3 is a side view of the boat seat beverage holder;
FIG. 4 is a top view of the boat seat beverage holder;
FIG. 5 is a bottom view of the boat seat beverage holder;
FIG. 6 is a side view of the boat seat beverage holder alternative configuration;
FIG. 7 is a top view of the boat seat beverage holder alternative configuration;
FIG. 8 is a bottom view of the boat seat beverage holder alternative configuration;
FIG. 9 is a perspective view illustrating the boat seat beverage holder secured to a boat seat; and,
FIG. 10 is a perspective view illustrating the boat seat beverage holder alternative configuration secured to a boat seat.
The broken lines in FIG. 1 through FIG. 10 are included for the purpose of illustrating the environment in which the article resides and form no part of the claimed design.