Strap for Hydroconquest Chronograph Tachymeter Silver

The lug width of the Longines HydroConquest L3.651.4.76.6 is 21mm. This measurement is constant across the model and represents the internal distance between the two case lugs. Measurement must be made with a digital calliper for precision, as even 1mm deviation will result in incompatibility or lateral movement of the strap during wear.

For this 41mm diving chronograph, we recommend Nile crocodile straps with vegetable tanning (dark brown or black) for daily wear, shell cordovan for aesthetic evolution over time, or hand-stitched fine-grain calf leather. For frequent diving, natural vulcanised rubber with a titanium deployante remains the pure tactical solution. The choice depends on balancing aesthetics, frequency of underwater use, and maintenance capability.

Strap replacement requires a specialised tool (spring bar tool) to compress the internal springs of the side lugs. Position the watch on a soft support, insert the tool into the lug slot, compress slightly and slide the lug outward. Proceed with the new strap by following the reverse process, ensuring both lugs are locked correctly. We recommend having this operation performed by an authorised service centre or Atelier Casati Milano to avoid damage.

Yes, any artisan strap with a 21mm lug width is compatible with the HydroConquest L3.651.4.76.6. Compatibility depends solely on lug width: 21mm means exactly 21 millimetres. Artisan straps from milanostraps.it are manufactured to this precision standard. However, we always recommend measuring the original lug with a calliper to exclude minor manufacturing variations, especially on pre-owned watches.

On a sports watch with frequent diving use, a leather strap typically lasts 2-4 years before requiring restoration or replacement. Durability depends on immersion frequency, maintenance (rapid drying after bathing) and tanning quality. Vegetable-tanned leather ages elegantly whilst developing patina, but deterioration accelerates in salt or chlorinated environments without care. We recommend rotating between straps (leather and rubber) to extend the lifespan of each. Atelier Casati Milano offers an 18-month guarantee and restoration service to extend longevity.