Grand slam force Grand slam force The Grand Slam Force is a bidding convention in contract bridge that was developed by Ely Culbertson in 1936. It is intended to be used in cases where the combined hands of a partnership are so strong that a slam (winning at least 12 tricks) is a near-certainty and a grand slam (winning all 13 tricks) is a possibility. It allows one partner to gain information on the quality of trumps in the other partner's hand. When this convention is in force, a bid of 5NT (five notrump), when it does not conflict with other conventions used
Bidding box placed over the bidding cards attaching to the box base. A bridge auction consists of a sequence of "calls" (a bid, pass, double, or redouble) made by each player in turn, until it is concluded by a sequence of three consecutive passes. With the transition from auction bridge to modern contract bridge, the bidding has become more complex, and conventional auctions often last through several rounds of bidding. Such long auctions are hard to memorize and review. In addition, oral bidding causes noise in tournament halls, and auctions can be easily overheard at the other tables. Bidding boxes were invented