Improving Jacoby 2NT
(Courtesy of Bob Crosby)
Jacoby 2NT shows a forcing major raise with 4 trump . What it does not show is a good suit as a source of tricks or you would have made a 2/1 and jumped in the major. Also , what it does not show is a singleton or else a splinter would have been a more beneficial bid.
The Jacoby 2NT is an old convention . Bergen , Martel and the Swedes have improved it . Serious 3NT theory can also assist the effectiveness of the Jacoby 2NT . The main complaint about Jacoby 2NT is that it does not show minimums or maximums with singletons . The treatment also did not show minimums very well as the jump to game opposite an unlimited hand jammed slam exploration to the 5 level. The old treatment also does not allow the Jacoby 2NT hand to “explore” the other hand very well. The following treatment is my opinion is a better way to play Jacoby 2NT.
The 3C bid should be reserved to show any minimum even with singletons. This eradicates the horrible leap to game to show a minimum and allows the other hand to ask for the singleton if there is still slam interest after a shown minimum . Why show a singleton if you have a minimum and help the opponents with their lead ? The principle of concealment with minimums comes into play. This leaves the opening leader in the dark where declarer can have a singleton on an auction
If partner has slam aspirations and wants to ask for the singleton , she bids 3D and you bid up the line to show your respective stiffs. With spades agreed , 3H stiff heart , 3S stiff diamond and 3NT stiff club. With hearts agreed 3H stiff diamond , 3S stiff spade & 3NT stiff club . For memory purposes , the trump suit always shows the diamond splinter , 3NT always the club splinter and natural for the major splinter. With no singleton you Q bid at the 4 level . With no singleton and nothing to Q bid , you bid game.
The 3D bid is reserved for all good hands with a stiff minor . Partner bids 3H and you reply 3S with a singleton diamond and 3NT with a singleton club. With this treatment you know the singleton at the 3 level and the additional fact that partner has a good hand. Without duplication of value , Q bidding will commence under game.
This treatment leaves the 3H rebid open to show the singleton in the other major with a good hand. With spades agreed , you have the natural rebid open to show a 6 card suit with a minimum . With hearts agreed , the jump to game shows a 6 card suit minimum with no singletons.
Jacoby 2NT is a you tell me type of bid . If you want to reverse that process you use the “Serious 3NT”. All good hands where you want to take control and show serious slam interest is done by the “Serious 3NT” . This forces partner to Q bid . You may have a singleton , a void , a 6 card suit or whatever but you want to take control rather then tell partner what you have. The 3NT bid switches captaincy of the auction . This bid tells partner that the next bid (if your Q bidding goes well ) will probably be KCB Blackwood.
A jump at the 4 level shows a two suiter with minimum values. A jump at the 5 level is Exclusion Blackwood with a void. Two suiters with maximum values would probably be bid by the “Serious 3NT” route where you need to discover specific controls for slam.