We got a zero on this hand despite the fact that our opponents missed an easy game. Nevertheless, it is a pretty good illustration of the various means of interfering against a weak 1NT opening.
Board #1
North dealer
Neither side vulnerable
| | North
♠ A K 9
♥ 10 9 5
♦ A 8 7 3
♣ Q 8 4
| | West
♠ 9 6 5 4
♥ A 7 4 2
♦ ——
♣ K 9 7 6 5
| | East
♠ Q 10
♥ K Q J 6 3
♦ J 10 9 2
♣ A J
| | | South
♠ J 7 3 2
♥ 8
♦ K Q 6 5 4
♣ 10 3 2
| |
|
| | | | |
| South | West | North | East |
| | 1NT | 2♥ |
| P | 3♥ | P | P |
| P | | | |
I sat North, holding a "textbook" weak 1NT opener. East overcalled 2♥. There was a little confusion as to whether it just showed just hearts or hearts and a minor. It mattered little to West, whose hand was clearly good enough for a raise. East declined the invitation. We did not immediately take our two spade tricks, but we did get one in the end. East-West scored 230.
Never mind that the other two East-West pairs found ways to go down in some contract. Let's look at East-West's bidding. If they were playing Cappelletti (or, for that matter, Woolsey), East should start with 2♥ to show hearts and a minor. Since North's bid shows a hand that would, for most players, suggest an opening bid of 1♣ or 1♦, West's overcall should show at least ten points and pretty good suit(s), the same as for an overcall of 2♣ after a 1♦ opener. East has at least one trick more than this.
West's raise to 3♥ shows support. How much strength does it show? Since West could have just passed, it must be invitational. East could have had only ten points and, depending on their agreement, only four hearts. East has considerably more than that, and, in my opinion, should have bid game.
This illustrates why it is very important to discuss the continuations after interfering in a weak 1NT auction. West reasonably thought that a hand with only two honors could not bid game. East reasonably thought that his hand was unexceptional. Neither felt the urge to bid game.
In contrast, if North-South had been playing a strong 1NT, East would have overcalled 1♥, not 2♥. South has enough to raise to 2♦. West would probably cue bid, and East would clearly accept the invitation. Who knows what might have happened after that?
One more point. I think that Mohan's transferring approach might have helped. After North's original 1NT, East could bid 2♦, a transfer to hearts. West might consider super-accepting the transfer, but let's assume that she only bid 2♥. East could then bid 3♦ as a game try. West would now appreciate the synergy of her four-card support and diamond void and surely would bid game.
I think that I may have convinced myself to try Mohan against weak 1NT openings.