1981-1989: The «Skinny» Ingenieur SL

with automatic (cal. 375x) or quartz (cal. 2250) movement

deutsche Version
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The quartz models (1981/82-1987)


Specifications:



picture

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 reference name
movement
 listed case

bracelet/strap
dials
measurements
remarks
3305 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»)
cal. 2250

quartz

date

 1981/82-1987 stainless steel on steel bracelet

mixte (SS/14 ct. YG) on mixte bracelet

mixte (SS/14 ct. YG bezel) on steel bracelet
black

plated rhodium

white - roman

gilt
ø: 34 mm

h: 8.8 mm

water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on ETA quartz ebauche
3315 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»)
cal. 2250

quartz

date

 1983-1987 stainless steel on leather or soft strap

mixte (SS/14 ct. YG) on leather or soft strap

18 ct. YG on leather or soft strap
black

plated rhodium

white - roman

gilt
ø: 34 mm

h: 8.8 mm

water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on ETA quartz ebauche
9703 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»
cal. 2250

quartz

date

 ca. 1982-1984 18 ct. yellow gold on gold bracelet
black

gilt

white - roman
ø: 34 mm

h: 8.8 mm

amagnetic to 40,000 A/m

water resistant to 6 atm

movement based on ETA quartz ebauche,

based on ref. 3305
9721 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»)
cal. 2250

quartz


1981/82-1987

(sold out by
July 1985)

 18 ct. yellow gold gold
on gold bracelet
with diamonds on bracelet, bezel & dial
gold (pavé)
ø: 34 mm

h: 8.8 mm

water resistant to 6 atm

amagnetic to 40,000 A/m

movement based on ETA quartz ebauche
9724 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»)
cal. 2250

quartz

 ca. 1982-1985? 18 ct. yellow gold gold
on gold bracelet
with diamonds on bezel
black

gilt

plated rhodium

white enamelled
ø: 34 mm

h: 8.8 mm

water resistant to 6 atm

amagnetic to 40,000 A/m

movement based on ETA quartz ebauche
9730 Ingenieur SL Quartz

(AKA «Skinny Ingenieur»)
cal. 2250

quartz

date

 1980?-1985 18 ct. yellow gold on gold bracelet
gilt

[white]

[black]

[plated rhodium]
ø: 34 mm

h: 8.8 mm

amagnetic to 40,000 A/m

water resistant to 6 atm

movement based on ETA quartz ebauche

based on ref. 3305

The first version of the automatic models (1983-1985/86)


Specifications:

  • automatic calibre 375 with ball bearing rotor and date display
    • based on ETA production (calibre 2892)
    • diameter: 28.00 mm
    • height of movement: 3.75 mm (hence IWC's naming of the calibre)
    • number of jewels: 21
    • frequency: 28,800 A/h = 4 Hz
    • balance spring: flat
    • fine adjustment: Etachron
    • total production: 9,940 pieces (only part of which was used on Ingenieur models)
  • tripartite screwed case
    • steel and mixed cases water resistant to 12 atm
    • gold cases water resistant to 6 atm
    • top part with bezel: flat surface with 5 recesses (for screwing tools) in stochastical position
    • amagnetic to 40,000 A/m, movement protected by Farraday's cage made of soft iron inner case and soft iron dial bottom
    • Glass: sapphire
  • Ingenieur- and SL-Logo with scripture AUTOMATIC above index at 6 o'clock
  • straps and bracelets (metal bracelets of SL type II with raised interlinks)
    • leather
    • soft band
    • stainless steel
    • mixte (stainless steel/14 ct. yellow gold)
    • 18 ct. yellow gold
       


picture

(click on thumbnail
for enlarged version)

 reference name
movement
 listed case

bracelet/strap
dials
measurements
remarks
3505 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 375

automatic

date

 1983-1984/85 stainless steel on steel bracelet

mixte (SS/14 ct. YG) on mixte bracelet
black

plated rhodium

[white]

[gilt]
ø: 34 mm

h: 8.8 mm

w: 117 g (mixte/mixte)
water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892
3515 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 375

automatic

date

 1983-1984/85 stainless steel on leather or soft strap

mixte (SS/14 ct. YG) on leather or soft strap

18 ct. yellow gold on leather or soft strap
black

plated rhodium

[white]

[gilt]
ø: 34 mm

h: 8.8 mm
water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892
9225 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 375

automatic

date

 1983-1984 18 ct. yellow gold on gold bracelet
black

gilt

plated rhodium

white enamelled
(tritium & non-tritium)
ø: 34 mm

h: 8.8 mm
water resistant to 6 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892

base reference 3505
succeeded by reference 9230

Special edition



picture

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 reference name
movement
 listed case

bracelet/strap
dials
measurements
remarks
0914 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 375

automatic

date

 ca. 1983-1984 18 ct. yellow gold gold on gold bracelet
with diamonds on bracelet, bezel & dial
(special setting)
gold (pavé)
ø: 34 mm

h: 8.8 mm

special edition (probably 2 pieces)
for Sultanate of Muscat and Oman

movement based on ETA cal. 2892
case based on reference 9225

auctioned at Crott's on 7th May 2005
(case number 2,394,336)

 

The 2nd version of the automatic models (1985-1988/89)


Specifications:

  • automatic calibre 37531 (and 3752 resp. 37521 ?) with ball bearing rotor and date display
    • based on ETA production (calibre 2892-A)
      • calibre 37531 with oscillation weight made of gold
      • calibre 3752 ? with oscillation weight made of heavy metal
      • diameter: 25.60 mm
    • height of movement: 3.75 mm
    • number of jewels: 21
    • frequency: 28,800 A/h = 4 Hz
    • balance spring: flat
    • fine adjustment: Etachron
    • total production
      • calibre 3753x: 800 pieces (? includes calibre 3753, 37531, 37532)
  • case and other specifications identical with first automatic Skinny

The exact nature of the calibres used in the ref. 3506/3516 is not absolutely clear. IWC sources mainly name the calibre 37531, but I've seen examples whose plates were stamped calibre 3752 or 37521. Both were smaller than the caliber 375 (25.60 vs. 28 mm), but apparently identical except for the metal used for the oscillation weight. Since at least one of the examples with calibre 3752 known to me featured a gold-tipped rotor, it may well be that IWC adapted existing calibre 3752 for the use in the Skinny without changing the calibre name on the plate. Anyway, I've seen to many calibre 3753x equipped Skinny Ingenieurs to have some doubts about the production total of 800 calibre 3753x which is given by Jürgen King in his calibre overview published in Watch Journal (especially since it also includes some movements with reduced heights not used in the Ingenieur).
 



picture

(click on thumbnail
for enlarged version)

 reference name
movement
 listed case

bracelet/strap
dials
measurements
remarks
3506 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
(cal. 3752)

cal. 37531

automatic

date

 1985-1988/89 stainless on steel bracelet

mixte (SS/14 ct. YG) on mixte bracelet

mixte (SS/14 ct. YG bezel) on steel bracelet
black

plated rhodium

white

[gilt]
ø: 34 mm

h: 8.8 mm
water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892-A2
3516 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
(cal. 3752)

cal. 37531

automatic

date

 1985-1988/89

stainless steel on leather or soft strap

mixte (SS/14 ct. YG) on leather or soft strap

18 ct. yellow gold on leather or soft strap
black

(black military?)

plated rhodium

white

gilt
ø: 34 mm

h: 8.8 mm
water resistant to 12 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892-A2
9230 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 37521

automatic

date

 1984-1986 18 ct. yellow gold on gold bracelet
black

gilt

plated rhodium

white enamelled
(tritium & non-tritium)
ø: 34 mm

h: 8.8 mm
water resistant to 6 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892

base reference 3505
preceded by referenced 9225
9231 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
cal. 37521

automatic

date

 ca. 1985 18 ct. yellow gold on gold bracelet
with diamonds on bezel
gilt

...
ø: 34 mm

h: 8.8 mm
water resistant to 6 atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892

base reference 3505
9236 Ingenieur SL Automatic

(AKA "Skinny Ingenieur")
(cal. 3752)

cal. 37531

automatic

date

 1987-1989 18 ct. yellow gold on gold bracelet
gilt

...
ø: 34 mm

h: 8.8 mm
water resistant to 6 (catalogue 12) atm

amagnetic to 40,000 A/m

movement based on
ETA cal. 2892-A2

 

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