Lesson 9 -- Slam Bidding Tools

Slam bidding is where the big money changes hands at rubber bridge; so it isn't surprising that special tools exist for slam bidding.


Blackwood is a tool used to check to make sure that partnership isn't missing two aces before going to a small slam (or missing an ace for a grand slam). Blackwood is used after a trump suit has been agreed upon. Bidding 4NT asks the responder to show the number of aces he has: If the partnership has all 4 aces, 5NT may be bid to ask about kings, the responses are very similiar, except 6C shows no kings and 6NT shows all 4 kings.

Warnings about Blackwood

Blackwood himself once remarked something to the effect of: "If I had a dime for everytime a partnership was helped by Blackwood [the convention], I'd be well off. If I had that dime for each time it was mis-used, I'd be a millionaire." There are several warnings about Blackwood that you should remember. There are other rules, but those few will be a good start.

Oops! Overshooting the contract

Sometimes, because of blackwood, you might get too high. For example, if clubs are trumps, and you need 2 aces to bid 6C, if partner has only 1 ace, he'll respond 5D. Obviously, you can't go to slam, and 5NT would be asking for kings. So, you bid 5S, which asks partner to bid 5NT, which you will pass.


Gerber is merely an extension of Blackwood, used mainly over NT auctions. See the NT pages for details.

Grand Slam Force

If all you need to make a grand slam is good trumps, then Grand Slam Force (GSF) is a useful convention. Bidding 5NT (without having previously bid Blackwood) asks your partner to bid 7 of your suit if he has two of the tip three honors in trumps, and to bid 6 otherwise.

If you have previously bid 4NT (Blackwood), then you can use a 6 of a new suit bid as the Grand Slam Force (This is technically called Josephine.) But I don't recommend pulling that on a partner without discussion.

Cue Bidding

By far the most powerful (and complicated) method if investigating slam is by Cue Bidding. Typically, you cue bid over powerful auctions, such as 1H-3H or 2C-2S-3S. After a trump suit is agreed, bidding a new suit typically shows first round control (an ace or a void). If you skip a suit, you imply that you are missing the control. If you ever run out of things to bid, you just go back to the trump suit (inviting a pass from partner). Of course, since Cue Bidding is a natural method, there are many different ways to cue bid. Do you: Cue Bidding controls should be discussed in any partnership.


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