Blackwood bridge convention

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To explore the opportunity of playing a Slam, which can earn the partnership big points bonuses, one player in the partnership usually needs to have at least a stronger-than-average opening like a One No-Trump bid (minimum 15 points), and the partner needs to have close to opening-point strength as well (minimum 12 points). Generally, you need at least 29 points between the two of you to even start thinking about a Slam.

But even if the partnership has a total of 36 points between the two hands, they will still not be able to make a Grand Slam in most cases if the four missing points are represented by an Ace. The ability to control suits with Aces and Kings (or voids) is vital in determining the viability of playing a Slam contract. Some experienced players bid Slam contracts merely on points, but beginners and intermediate players usually feel safer about bidding a Slam if they have been able to ask their partner: “Hey, how many Aces and/or Kings do you have?”

Fortunately, people have invented conventions for this purpose that partnership may use to “ask for Aces (and Kings)” since the possibility of making a Slam usually depends on missing no more than one Ace.

One of those conventions (the other main one is Gerber) is called Blackwood. Under the Blackwood bridge convention, the 4 No-Trump bid means asking for Aces. All answers are at the 5 level, with clubs, the lowest suit, meaning 0; the next lowest suit diamonds meaning 1, etc. In this convention, 5 No-Trump is used to ask for Kings and the answer, is given in the same fashion with clubs meaning 0. All answers are at the 6 level, so before any partner proceeds to ask for Kings, he/she had better be sure that the partnership can make a Small Slam regardless of the answer on the Kings question. Asking for Kings is usually a way to determine if there is a possibility for a Grand Slam.

The disadvantage of the Blackwood bridge system over the Gerber system is that there is a danger of getting too high too fast. The advantage is that there is less confusion over what the bids could possibly mean.

(A 4 NT bid virtually always means asking for Aces, although a partner may indeed pass a 4 NT bid even if he knows that partner is looking for a Slam. If one partner has opened 1 NT (with a 15-17 point range) and the other partner has an opening-strength 13-point hand with a balanced distribution, he/she may jump straight to 4 NT.  This is a so-called “quantitative” 4 NT bid. It means that if the opener had a minimum 15-point NT opening, he/she should pass. If he was at the top of his/he 15-17 range, he should answer the 4 NT bid as if it was meant as asking for Aces.)

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