There is a whole book on RKCB written by Eddie Kantar. An e-copy is downloadable. I’m just going to use last week’s play hand (hand 22 http://bridge99.co.uk/cbc/Res/hands121002.pdf) to show RKCB in its full glory. We play 41-30 (5C shows 4 or 1 key cards). Experts prefer 41-30 to 30-41 as it facilitates a second question about the queen of trumps
EW have little, too little to contest. Note that E has a balanced hand though everyone else has serious shape; you can’t assume that if your are balanced so will everyone else be, or the converse.
South is not strong enough for 2C—23+ HCP or 9PT in spades, there are only 8PT and 18 HCP. Of course 2S would be weak. Some people locally play non-forcing strong-2s: experts disapprove but if you were playing NF strong 2s it would be suitable. However there is a risk in tampering with bits of the system so don’t be tempted. What follows is an example of staying true to the system. We have a rich repertoire of support bids because usually we need partnership support to win high level contracts—game and beyond. Don’t you love it when partner supports?
North wants to show a good side suit and support for spades. He:
I rarely make a jump-shift on a hand with so few HCP but it does hold the values for an opening bid and N knows that 4S is safe opposite any South holding, so 3C followed by spade support is the system bid.
South bids 3S. The partnership is in a game-forcing sequence, and S will probably make another attempt later if there is a Spade fit—as the hands seem to have at least 30 HCP and so are in the slam range. South’s hand is not limited—except by the original inability to open 2C. S denies a second suit and denies a balanced hand so must have 5S.
North bids 4S to finishing the description of his hand: primary spade support and a decent side suit.
South knows about 9 cards in the N hand: 5 Clubs with two of the top three honours and 4 Spades. S can clearly visualise the slam; only 3 trumps out, so no trump loser; some values in North to take care of at least some of the red suit losers; controls in clubs and length for discards.
Now South knows of the spade fit, he can apply the Losing Trick Count; the LTC only applies when a suit fit has been established; either player can apply it whether or not his partner does. For the LTC, each suit is counted individually. The LTC can be elaborated for greater accuracy, wht follows is the primary crude form. A singleton is one loser unless it is the ace when it is no losers. A doubleton is two losers unless it includes the K when it is one loser or both the A & K when it is no losers. A longer suit, however long, has 3 losers less the number of top top honours held, eg AQx is one loser. An opening bid (or a jump shift) typically has 7 losers. In the above hands, N has 7 losers (3 spades, two hearts, a diamond and a club), S has 5 losers, two hearts, two diamonds and a club. To apply the LTC add your losers to partner’s assumed losers and subtract from 24 to estimate the number of probable tricks; here 24 - 7 - 5 = 12 and South should sniff a small slam.
Now the value of the jump-shift becomes apparent, although game is already reached it is easy for South to continue seeing the chance to chuck losers on the clubs. And the singleton club also guarantees there cannot be two quick losers. By bidding 4NT, here S becomes the senior hand and will determine the final contract.
5C. by North as expected shows the missing key card, the Club Ace.
5S would be sign-off. Next suit up (5D) would be asking for the Q of trumps. 5NT by the senior hand promises all key cards and asks for Kings to be cue bid, starting with the cheapest (ignoring the KT which N in some other hand he would have already shown or denied).
North confirms holding the KC: “6C”.
Now, in the most advanced form of RKCB, South can ask for control of a side suit. Since South’s D and H are identical and he can only ask about one, it seems to be a guess which to ask about. On this hand, the cheaper suit allows room for a useful response which asking after Hearts might not, so South bids 6D.
North responding in accordance with the system schedule bids 7C.
Note that if North’s red suits were reversed he would have bid one step to show only third round control in diamonds and South would subside in 6S even though the 7-level contract is just as safe: no bidding system is perfect but one that can get to this grand slam on 30 points is still quite impressive.
South signs off in 7 Spades, at last.
These extended RKCB responses are courtesy of http://www.gravesendbridgeclub.org/CB/conventions/RKB.html. I don’t actually play these with anybody! Just showing that good system can reach challenging contracts
It is easy to stop in any number of the agreed suit, there is no sure way to get off the treadmill to end in 5 NT if the agreed suit is Spades. An impossible bid should wake partner up. For example asking for the Q (5H) and then bidding 5NT when partner denies it (5S) should be a sign-off. Moral, make sure you know the spell to stop the broom before you start your sorcery.
For completeness, if the senior partner asks after QT, the junior partner signs off at the lowest level of trumps without it, bids NT with QT but no king and cue-bids the cheapest king to also promise the QT.
If you have the tools to find a grand slam, you need the card-playing skills to make it.
Deep finesse, the analysis program, says 7S is makeable from either hand on deal 22 (remember the interpretation of the box in the bottom right hand corner). On the night, the stronger section mostly bid 6S making six or seven; in the weaker section, most stayed at 4 making 6 a few (including Tom and John) bid 6, one making 7. Just one pair bid the grand—against Roy, not really his night. On Wednesday, under time pressure as if at the table we couldn’t see how to make 7 but it is as easy as I first suggested assuming clubs break 4-3:
1, win the opening lead with an Ace (it doesn’t matter which, though obviously the exact card to a later trick will vary, I’ve assumed H);
2, draw one trump (seeing the even break but it doesn’t matter),
3 cash AC;
4 ruff a club;
5 cross to N with a trump (drawing the last);
6 ruff another club (pleased to see both follow, one club out, dummy has K and small in clubs;
9 ruff a D;
10 cash KC throwing H;
11 cash small club throwing H;
12, 13 claim with your 2 remaining trumps.
Raises after 1 NT, 2NT
After an opening 1NT, 2NT is not support, but a transfer to Diamonds (with 3C being super-acceptance with Qxx or better and 3D accepting the transfer with lesser support). You can’t raise 1NT to 2NT directly. With a minor suited hand, you must choose between passing or raising to game. With a major, you can bid Stayman in the hope of finding a fit and if partner shows neither (2D) or the wrong one you can bid 2NT (with both majors, opener will then convert to 3 S).
3NT shows a hand good for game: at least equivalent to an opening NT in HCP or a minor suit trick source either solid or robust with an entry, at most a hand where slam in improbable even if partner holds a maximum. You might have as few as 10 HCP with a sound trick source and won’t have more than 18 HCP.
4NT A better hand, 19-20 HCP, invites to slam by bidding 4NT; this is not Blackwood, it says “please raise to 6NT if upper range within your 1NT opening”.
6NT, 7NT Still stronger responding hands bid on the expectation that 33 HCP is enough for a small slam and 37 for a grand. A balanced 21/22 HCP bids 6NT immediately over 1NT, 25+ bids 7NT. and watches partner panic.
5NT A 23-24 HCP hand can bid 5NT, asking partner to choose a small or grand slam depending on HCP; I know no-one who has told me they play this: the risks of languishing in 5 should be small—what else can it mean?
The immediate raise to 4NT is neither available nor needed for Ace asking; Gerber 4C achieves this.
Support bids after 2NT are much as after 1NT but 8 points lighter as opener is now 20-22 not 12-14.