Strong 1♣

Blueberry employs an approach similar to Viking Precision 2007. However, I frown at extensive transfers. It would be annoying to declare the phoney strain the strong opener actually holds. See natural positives for the full argument.

Natural positives

Viking Precision swaps the suits in its positive responses: 1♥ shows spades, 1♠ hearts, 2♣ diamonds, and 2♦ clubs. Opener then relays, so the strong hand usually declares responder’s suit. Blueberry keeps these responses natural for four reasons.

• The stakes are small. A positive response forces to game, so both hands hold honors worth protecting from the opening lead. The declaring side matters most when the strong hand faces a bust, and after 1♣ - 1♦ opener names the suits anyway.
• Opener need not relay. The Viking card lists only the relay after 1♥ and 1♠. Blueberry opener can also rebid naturally below 2NT, so responder is not the only hand the defenders hear described.
• The relays take the right strains. 1♣ - 1♥ - 1♠ gives opener the spades, and 1♣ - 1♠ - 1NT gives opener the notrump. Only responder’s own suit is left to responder.
• Opener keeps the other major. A swapped response bids a suit responder need not hold. Viking opener can never declare spades after 1♣ - 1♠ or hearts after 1♣ - 1♥, however good the suit.

The price is real. When opener relays to the end and the contract lands in responder’s suit, the described hand declares and the strong hand is dummy, so the defenders know both shapes. Viking never pays this price in spades, where the relay itself is 1♠. It does pay in hearts whenever responder rebids them: 1♣ - 1♠ - 1NT - 2♥ shows a balanced hand or 4+♠, which includes 5332, the most common shape with a 5-card suit.

Minors 2♥

Three-suited 2♠, 2NT

Opener relays. Responder directly reports the singleton so the right hand declares.