A Slatted Bottom Rack is a ventilation board that fits between the bottom hive body and the bottom board (Langstroth Hive). It provides cluster space for bees, allows air circulation without allowing a direct draft on the brood, and helps prevent swarming.
Slatted Bottom Rack Plans - 1 page PDF file
The Bovard Rack
It converts a standard bottom board into a Killion slatted bottom board so the queen will lay in the lower brood chamber.
CHARLES J. KOOVER
GLEANINGS IN BEE CULTURE - June, 1968
To the late Dr. C. C. Miller belongs the credit of realizing that bees need more room under the bottom bars. Sound as it was, the idea was never accepted by the beekeeping industry. He made two-inch-deep bottom boards and used them as long as he kept bees. Soon he discovered that bees build comb underneath the bottom bars, so the idea of a slatted rack under the frames was conceived. This served the purpose very well.
Carl E. Killion, one of his successors in comb honey production, discovered the principle of the four-inch-wide solid board instead of slats near the entrance. This was a most important improvement and it did away with bees chewing the combs along the bottom bars.
Still the deep bottom board and rack did not become the accepted standard of the industry. The reasons are easy to see. It takes two special pieces of equipment. The rack is fragile and is time-consuming to make. Furthermore, spacers have to be attached to prevent the bees from propolizing it to the bottom board.
In a moment of ingenious thinking, Richard F. Bovard of Honolulu, Hawaii, has eliminated all these objections and has created the ideal entrance to the hive without changing in any way the equipment now in use. He has come up with the idea of a two-inch-deep frame of the same dimensions as the hive body, 16-1/4 x 20 inches. In this are fitted the four-inch-wide board and a number of 3/4-inch-wide slats. Proper space of 5/16th inch is maintained between bottom bars and slats and between the slats themselves. That's all there is to it. It is simplicity itself. It fits under the brood chamber on top of the bottom board. It is strong and asks no favors. It can be easily attached to the brood chamber and bottom board for migratory purposes. The Western beekeeper with his standard 3/8th inch entrance can use it and so can the Eastern beekeeper with his choice of a 3/8th or 7/8th inch entrance. This rack provides a single wide entrance clear across the front of the hive instead of three separate entrances as with the Miller rack. It protects the combs four inches back from the front entrance against robbers, wax moths and winds. There is nothing to be propolized onto the bottom board. And it is free from any objections, even the most critical beekeeper might raise. It adds but little weight to the hive, three pounds to be exact.
Here is a piece of equipment that should be universally accepted, just as the inner cover and telescope cover are part of a hive. It is easy to manufacture and simple in its assembly. It can be sold in the flat unassembled or factory assembled. It is hoped that hive manufacturers will add it to their line of bee supplies.
Beekeepers are notoriously slow in accepting new ideas, they still live in the horse and buggy days as far as their bee equipment goes, yet for their personal comfort they expect the latest gimmicks in their automobiles and trucks.
This-easy-to-use slatted rack ends once and for all poor ventilation and excess moisture. It is up to the beekeepers now to discover for themselves a whole new phase in beekeeping.