Instead of a full-fledged bidding system, Watermelon Dutch Doubleton is a minimalist plugin for 5542 systems, specifically designed for 2/1 and SAYC.
- 1♣ - 1♦ = catchall relay
- 1♣ - 1M - 2♦ = artificial reverse
- 1♣ - 2♦ = FG, 5+♦, a natural adjunct
This book fits the following regulations:
- Green (natural) classification under the WBF Systems Policy
- ACBL Basic Chart
- Optional agreements may require the ACBL Basic+ Chart.
Notation
This book follows Strawberry Polish Club for hand evaluation, bidding notation, and punctuation in tables and prose.
References
- Jan Eric Larsson. Good, Better, Best: A comparison of bridge bidding systems and conventions by computer simulation. ISBN 978-1771402415
- Thomas Andrews. Thomas’s Bridge Fantasia
- Bridge Base. GIB Bid Descriptions
Dutch Doubleton
- Dan Neil. Professional Dutch Doubleton Bidding System
- Sjoert Brink & Bas Drijver. (WBF convention card)
- Rosalind Hengeveld. Dutch Doubleton
Polish Club
- Chen-Pang He. Strawberry Polish Club
- Krzysztof Jassem & Tomek Brus. Polish Club 2020: Expert. ISBN 978-1771402248
- Krzysztof Jassem. Wspólny Język 2020 Standard
- Krzysztof Jassem. Polish Club International 2010
Openings
| 1♣ | 11–23, 2+♣ |
| 1♦ | 11–23, 4+♦ |
| 1♥♠ | 11–20, 5+# |
| 1NT | 15–17, 2–5♠, 2–5♥, 2–6♦, 2–6♣ |
| 2♣! | 21+, (5+♠♥ or 6+♦♣ or 24+) |
| 2NT | 21–23, 2–4♠, 2–4♥, 2–6♦, 2–6♣ |
Prefer 1♦ to 1♣ when holding (xx)45 because there is hardly any way for a 1♣ opener to show 4+♦ however strong. This canapé deviates from standard natural bidding.
The ACBL Basic Chart forbids a natural 2NT from bearing a void or a singleton < Q. Thus, 1♣♦ have to handle strong hands which are disqualified from 2NT and lack a rebid after the 2♣ opening.
Basic+ agreements, optional
The agreements in this section requires the ACBL Basic+ Chart.
Off-shape 2NT
Basic+ allows all very strong 2-level openings.
| 1♣ | 11–20, 2+♣ |
| 1♦ | 11–20, 4+♦ |
| 2NT | 21–23, 0–4♠, 0–4♥, 0–6♦, 0–6♣ |
Preemptive 2NT
Basic+ allows 2NT to show 5+ 4+ minors. The unusual 2NT is therefore permitted.
| 1♣ | 11–20, 2+♣ |
| 1♦ | 11–20, 4+♦ |
| 2♣! | 21+ |
| 2NT | 4–10, 5+♦, 5+♣ |
Dutch 1♣
My approach to respond to the 1♣ opening is a lawyer’s Polish Club. The 2♦ response is natural and game-forcing, while 1♦ is a generic catchall. This way, 1♣ - 2♦ would pass more system regulations around the globe.
System regulations are more liberal in the Netherlands and most of Europe. Dutch players often adopt conventional jump responses. For example, Brink–Drijver and Rosalind Hengeveld play the Multi 2♦ response.
In countries with more conservative regulations, conventional jump responses are restricted. On the other hand, artificial 1♣ - 1♦ is often tolerated. The ACBL Basic Chart and 🇯🇵 JCBL Convention List C explicitly allow any 1♦ response to a constructive 1♣.
| 1♣ - | |
|---|---|
| P | 0–5, 4–5♣ |
| 1♦! | 0–11 or BAL 16+ |
| 2♣ | LIM+, 5+♣ |
| 2♦ | FG, 5+♦ |
Negative 1♦
This relay contains all hands with no other suitable call.
| Strength | Distribution |
|---|---|
| 0–5 | Unwilling to play 1♣ |
| 6–11 | 0–3♠, 0–3♥, probably UNBAL |
| 16+ | 2–3♠, 2–3♥, 3–4♦, 3–4♣ |
Dutch 1♣ is limited by the strong 2♣ opening and hardly has any 5-card major. Unlike Polish 1♣, the strongest hands in the Dutch 1♣ are still quasi-natural, either relatively balanced or long in clubs.
| 1♣ - 1♦ - | |
|---|---|
| 1♥♠ | 11–17, (4+# or BAL MIN 3=#) |
| 1NT | 18–20, 1–4♠, 1–4♥, 1–4♦, 2–5♣ |
| 2♣ | 11–17, 5+♣ |
| 2♦! | 21–23, 1–4♠, 1–4♥, 1–4♦, 2–5♣ |
| 2♥♠ | 18–20, 4+#, 5+♣ |
| 2NT! | 18–20, 6+♣ |
| 3♣ | 15–17, 6+♣ |
Natural 1M
| 1♣ - 1M - | |
|---|---|
| 2♣ | NF, UNBAL 5+♣ |
| 2♦! | ART REV: FG or (INV, 3= SUPP) |
I propose 445566-like step responses from Polish Club. Ingberman has a point to bring Lebensohl from 2NT down to a cheaper 4SF. I take this idea further. Borrowing the step responses, it is now possible to play a 7-card fit at the 2-level.
| 1♣ - 1M - 2♦ - | |
|---|---|
| 2OM! | FG, 4=M |
| 2M! | NF, 4=M |
| 2NT! | FG, 5=M |
| 3♣! | MIN, 5=M |
| 3♦! | FG, 6+M |
| 3M | NF, 6+M |