During 1941 an investigation was conducted to evaluate the effectiveness of bombing raids over a 52 day period. This investigation revealed that only a quarter of bombers reporting hits on target were actually on target and that 95% of those that missed, missed by more than 5 miles.
At this time there was no GPS and most navigation carried out was by "dead reckoning", calculated by journey start and end points, bearing, speed and elapsed time. Timepieces in use at this time were not sturdy or accurate enough to produce reliable results, mainly due to high magnetic fields from the map painting radar screens used in aircraft. In 1946 or 47 the RAF decided that they needed a more reliable timepiece and the Air Ministry approached Goldsmiths and Silversmiths Ltd to specify and acquire a high quality watch. The main specifications were chronometer grade, high anti-magnetic properties (12,000A/m) and good legibility. Two companies eventually won the tender to supply, International Watch Company (IWC) and Jaeger LeCoultre (JLC) and the watches, both designated Mk 11, entered service in 1949.
Mk 11 is the Air Ministry designation for the watch, it is not a manufacturer's model number.
Both had long, slender hands but proved difficult to read in low-light conditions and so in 1952 the hands of the IWC were changed to improve legibility by the introduction of a shorter and thicker hour hand.
The Smiths Navigator is a faithful revival of the Mk 11, using the original Air Ministry specification but with higher anti-magnetic properties (20,000A/m) and sapphire crystal
Supplied in a 2- watch travelling case with 24 months guarantee.
SMITHS NAVIGATOR PRS-48
316L stainless steel, brushed finish with polished bezel
Diameter 36mm
Lug to lug height 46.4mm
Thickness 11.3mm to top of the crystal
Lug spacing 18mm
Anti-magnetic 20000 A/m
WR 10ATM/100 metres/330 feet
77 grammes with strap
Full anti-magnetic cage, screw back, drilled lugs
Semi-matte black, white printed numbers
Triangle and cardinal indices SuperLuminova X1-C3
Polished steel frame, luminous fill
Luminous: SuperLuminova X1-C3
Box sapphire, 30.7mm diameter x 1.8mm thick with anti-reflective coating on the underside
Sellita SW210 "Top" version 19 jewels, manual winding, incabloc, hacking seconds, fully decorated and 28,800 BPH
Pigskin fitted with push-button release deployant clasp
CASE
DIAL
HANDS
CRYSTAL
MOVEMENT
STRAP
SPECIFICATIONS
SMITHS Navigator PRS-48 black dial
SMITHS Navigator PRS-48 white dial
316L stainless steel, brushed finish with polished bezel
Diameter 36mm
Lug to lug height 46.4mm
Thickness 11.3mm to top of the crystal
Lug spacing 18mm
Anti-magnetic 20000 A/m
WR 10ATM/100 metres/330 feet
77 grammes with strap
Full anti-magnetic cage, screw back, drilled lugs
Semi-matte white, black printed numbers
Triangle and cardinal indices SuperLuminova X1-C3
Heat-blued steel frame, luminous fill
Luminous: SuperLuminova X1-C3
Box sapphire 30.7mm diameter x 1.8mm thick with anti-reflective coating on the underside
Sellita SW210 "Top" version 19 jewels, manual winding, incabloc, hacking seconds, fully decorated and 28,800 BPH
Pigskin fitted with push-button release deployant clasp