Front view
Dial, hands and bezel as delivered.
Case-back view
Case-back engraving and, where fitted, the sapphire display.
Movement
Calibre with its finishing and decoration.
On the wrist
Worn shot for proportion and strap drape.
Sinn · Hydro
Sinn Hydro 43 mm Slate Carbon
Reference 36783OR.18
Reference at a glance
- Brand
- Sinn
- Collection
- Hydro
- Model
- Sinn Hydro 43 mm Slate Carbon
- Reference number
- 36783OR.18
- Year / era
- 1961 · 1960s — pre-quartz mechanical era
- Complication
- GMT / second time zone
- Movement
- Automatic COSC chronometer
- Case material
- Carbon TPT
- Dial type
- Slate grey
- Strap / bracelet
- Rubber strap with titanium clasp
- Water resistance
- 500 m
- Limited-edition status
- Regular production, not a limited edition
Case, dial & bracelet
- Case dimensions
- 43 mm
- Case thickness
- 8.8 mm
- Case material
- Carbon TPT
- Bezel
- Fixed brushed titanium
- Crystal
- Sapphire with internal AR treatment
- Dial
- Slate grey
- Hands
- Blued steel Breguet-style hands
- Indexes
- Applied Arabic numerals with luminous coating
- Bracelet / strap
- Rubber strap with titanium clasp
- Clasp / buckle
- Pin buckle in matching case metal
- Water resistance
- 500 m
Movement
- Movement / calibre
- Calibre 25B — Automatic COSC chronometer
- Movement type
- Automatic, self-winding
- Frequency
- 21,600 vph (3 Hz)
- Power reserve
- 65 hours
- Number of jewels
- 21 jewels
- Complications
- GMT / second time zone
- Functions
- Flying tourbillon, power reserve
- Watchmaker
- Assembled and regulated by a single watchmaker, who signs off the piece before casing.
Production & market
- Production period
- 1961 – 1977
- Limited-edition quantity
- Not applicable
- Current market information
- Trades close to retail on the secondary market, with steady demand for full-set examples.
Designer
Jörg Hysek
Jörg Hysek left Rolex and Seiko's European studios to build a design practice in Geneva, giving houses such as Vacheron Constantin, Breguet, Seiko and TAG Heuer their sculptural, architecture-led cases before founding his own brand, HD3.
Historical significance
Sinn Hydro 43 mm Slate Carbon sits within Sinn's Hydro line, introduced in 1961. It carries the house codes established since 1961 — carbon tpt case, slate grey dial and automatic cosc chronometer — and is one of the references collectors use to date the evolution of the collection.
Interesting facts
- The case is finished by hand, alternating polished and satin-brushed surfaces in a single pass so the edges stay razor sharp.
- Early production dials show a slightly different minute track, and collectors pay a premium for them.
- The bracelet tapers across its length, which is why the profile looks thinner on the wrist than the specification suggests.
The House
Sinn
Brand facts
- Founding year
- 1961
- Founder
- Helmut Sinn
- Headquarters
- Germany
- Tier
- Affordable & Tool Watches
- Major collections
- 556, 104, EZM, U1, 903, Hydro
- Signature technologies
- Anti-magnetic silicon escapement · Shock-absorbing movement mounting
- Famous movements
- Automatic, 38-hour reserve · Automatic Powermatic 80 · Automatic COSC chronometer · Quartz
- Notable watches
- Sinn 556 42 mm Silvered 18k (1975) · Sinn 556 43 mm Slate Sapphire (1961) · Sinn 556 36 mm Mother-of-pearl 18k (1976) · Sinn 556 43 mm Ice 18k (1965)
Brand history
Sinn has spent more than 65 years refining a single idea: a watch should outlive its owner. From the earliest workshop pieces to today's 556, the house has balanced technical ambition with a recognisable design language, and its collections remain among the most closely followed by collectors worldwide.
Helmut Sinn established Sinn in 1961, working from Germany at a time when precision was measured by hand. The founder's obsession with finishing and accuracy still defines every Sinn calibre produced today.
Historical milestones
1961
Helmut Sinn founds Sinn in Germany.
1969
The quartz era forces Sinn to redefine mechanical watchmaking.
1990
Sinn enters the modern collector market with its signature lines.
2024
Sinn continues to produce 556, 104, EZM and other icons in limited numbers.