Your left-hand opponent opens one spade, your partner passes, your right-hand opponent jumps to four spades, and you overcall four no-trump. What message are you transmitting to partner about your hand? Sorry, but not all four-no-trump bids are Blackwood.
The most common example occurs after partner opens one no-trump or two no-trump. If you jump to four no-trump, it is quantitative, asking partner to pass with a minimum, to jump to slam with a maximum, and to guess well with a middling hand.
To ask for aces, respond four clubs, the Gerber convention. Four no-trump is Blackwood when there is a clearly agreed suit. For example, one spade — three spades — four no-trump. Or four no-trump is a wild leap into the stratosphere after partner has bid a suit. For example, one spade — two hearts — four no-trump. The given deal occurred during a private game in St. Louis. When South bid four no-trump, there was no agreed suit. His overcall showed a two-suited hand: at least 5-5 in two of the three unbid suits. After West competed to five spades, North knew to sacrifice, bidding five no-trump to ask his partner to show his lower-ranking suit, and six clubs doubled became the final contract.
This was the par result because five spades would have made for plus 450, and six clubs doubled went down two for minus 300. In high-level competitive auctions, four no-trump is usually best reserved to show a two-suited hand, not to ask for aces.
The most common example occurs after partner opens one no-trump or two no-trump. If you jump to four no-trump, it is quantitative, asking partner to pass with a minimum, to jump to slam with a maximum, and to guess well with a middling hand.
To ask for aces, respond four clubs, the Gerber convention. Four no-trump is Blackwood when there is a clearly agreed suit. For example, one spade — three spades — four no-trump. Or four no-trump is a wild leap into the stratosphere after partner has bid a suit. For example, one spade — two hearts — four no-trump. The given deal occurred during a private game in St. Louis. When South bid four no-trump, there was no agreed suit. His overcall showed a two-suited hand: at least 5-5 in two of the three unbid suits. After West competed to five spades, North knew to sacrifice, bidding five no-trump to ask his partner to show his lower-ranking suit, and six clubs doubled became the final contract.
This was the par result because five spades would have made for plus 450, and six clubs doubled went down two for minus 300. In high-level competitive auctions, four no-trump is usually best reserved to show a two-suited hand, not to ask for aces.