B-42 Marinemaster Diver Chronograph (640.10.141)

The Fortis B-42 Marinemaster Diver Chronograph Lot10208 Ref. 640.10.141 stands out because it pairs a bold pilot/diver style with Swiss automatic chronograph precision, offering clear timing functions, strong water resistance, and a rugged design that feels purposeful and sporty.

The watch shows a clear and functional dial with large Arabic numerals, multiple chronograph sub-dials for timing, and a day/date window that adds everyday usefulness. It often pairs a white or ivory dial with blue luminous hands and markers, which stand out well in various light conditions. The stainless steel case measures about 42 mm across and sits comfortably on the wrist, with sapphire crystal protecting the face from scratches. A unidirectional blue bezel around the dial gives a sporty edge, and the bracelet is usually solid steel with a secure folding clasp.

Inside, the B-42 runs on the Swiss automatic Valjoux 7750 chronograph movement, a classic well-known caliber for mechanical chronographs. This movement powers the main time, chronograph functions, and the day/date display while winding itself with wrist motion. It beats at 28,800 vibrations per hour and is robust and familiar to many watch lovers for dependable performance.

Fortis designed the B-42 series as part of its pilot and tool watch line, with roots in watches intended for professional aviation and durability. The “B-42” name refers to its approximate case size and its purpose as a Beobachtungsuhr (navigation watch) in a larger, highly legible format. Over the years this family has become known for strong build quality and a bold, functional aesthetic that suits both flying and everyday wear.

The watch appears to be in good condition, with minimal signs of wear. The case, Leather strap, and clasp show only light surface marks. The dial, crystal, and bezel look clean and clear, indicating careful use and good maintenance.

What do the different grading scores mean?

• BN 9.9: Brand new and unworn, with no signs of use.
• UN 9.5: Like new and unworn, but may lack original packaging or materials such as the box, links, tags, or bezel protector.
• LN 9.0: Like new and unworn, but only includes the watch without papers, box, or accessories.
• MT 8.5: Mint condition, lightly used with minor surface scratches or wear. Unpolished.
• VG 8.0: Moderately used, with scratches and one or two nicks on the case or crystal. Shows signs of polishing. The bracelet remains snug with minimal wear.
• GD 7.5: Shows signs of daily wear but is not abused, with noticeable polishing on the case. The bracelet shows clear signs of daily wear.

Watches with a rating below GD 7.5 are not listed for bidding to ensure that only high-quality timepieces are available to our members.