Left Silver-46.

Static rook, a rapid attack on a ranging rook · castles into Boat · ４六銀左戦法 yon-roku gin hidari

The idea

The Left Silver-46 is one of the Boat castle rapid attacks, the ways a static rook starts a fight against a Fourth File Rook before White’s Mino gets any stronger. Black builds the Boat in a few moves, with the king on 7h and golds on 5h and 6i, and brings the left silver out through 6h to 5g, the form ja.wikipedia says rapid attacks use most.

That position, the Left Silver-57 (move 23 below), is shared by four lines, and White’s silver decides which one Black plays. With the silver on 4c, as here, the left silver goes on to 4f, the diagonal Climbing Silver (斜め棒銀), and the third-file pawn hits the bishop on 3c; the Pawn-45 Early Fight is the other answer to 4c.

With the silver still on 3b, Black plays the Yamada Joseki or the Saginomiya Joseki. White’s Mino is the stronger castle in every one of them, so the attack has to land.

How it goes together

Both sides’ moves are shown, because this opening is an agreement rather than a system: one player cannot reach it alone, so a one-sided list of moves would be a fiction.

The plan once you are set up

• Build the Boat: king to 6h and 7h, right gold to 5h. Push the seventh, fifth and third-file pawns, and the rook pawn to 2e, so White’s bishop has to stand on 3c.
• Bring the left silver to 6h and then 5g. This is the shared starting position of four lines.
• Against White’s silver on 4c, take the silver on to 4f and push 3e.
• Swap off the second-file pawn before the rook goes to 3h, then trade bishops when White plays 4e, and drop the bishop back in.

What to watch for

• White’s 4e. It is the standard counter in every one of these lines: it hits the silver on 4f and opens White’s bishop. Here, do not take the silver on 3d with the rook: White takes on 8h with check and wins the rook.
• The difference in castles. ja.wikipedia says that even a position slightly better for the static rook is hard to win in practice, because White’s Mino is the stronger castle.

What it is played against

A Fourth File Rook with a Mino, played by White, with its silver on 4c. Against this line White swings the rook to 3b and fights back with the 4e push.

The sources disagree about who is better after the bishop drop that follows: shogi-joutatsu calls Black slightly easier to play, while two longer lines take White’s side. The slow alternative to all the rapid attacks is the Static Rook Anaguma.