Review: Panerai Luminor 31 Giorni PAM01631 new from WWG26

Panerai reaffirms their commitment to long power reserves with the Luminor 31 Giorni PAM01631 with a movement which will retain accurate timekeeping for 31 full days. We got a hands on session with this watch in Geneva, and here is our review.

Review: Panerai Luminor 31 Giorni PAM01631 new from WWG26 (live pics)

The Panerai Luminor 31 Giorni PAM01631 has a retail price of EUR 95,000. Limited Edition of 200 pieces.

The case, dial and hands

The case is the classical Panerai Luminor case in 44mm and brushed Panerai Goldtech case. The material is a proprietary gold alloy used by Panerai that features an intense red hue, achieved by combining 75% gold with a high concentration of copper (24 %) and platinum. The metal is more resistant to corrosion than traditional rose or red gold, but the hue looks like that of a rose gold case. The hands are traditional Luminor hands, with hour markers with heavy SuperLuminova infill as bars and the 12 and 6 in arabic numerals applied to the rehaut. The markers cantilever over the open worked movement which is fully visible from the dial side.

The dial is almost non-existant other than the rehaut with the indices, and exposes a fully skeletonised movement. What is interesting is a polarised date disc is only visible through the 3 o’clock aperture. Though it remains under the dial the rest of the days, it is not visible due to the polarisation of the glass and disc. Clever innovation.

A curved power reserve indicator shows the wind state of the barrel in steps of 5 days. The PAM01631 case has a water resistance rating of 100m.

The movement

The movement, caliber P.2031/S is impressive. This is the first time Panerai has done a movement with such a long power reserve. The caliber uses multiple barrels arranged in series to provide a low torque, fast rotation power system. This combination allows a long power reserve with low friction and stress to the pivots. The configuration calls for 4 barrels with a total of 3.3m of mainsprings.

A Torque Limiter system stops the movement after 31 days, though the barrel system will run for a full 36 days. This ensures that only the most linear portion of the torque curve is used, thus maintaining good chronometry.

What is also of note that this barrel system allows the watch to be fully wound from a depleted state with only 128 turns of the crown. This eliminates the need for tools unlike other month long movements. We discuss these more in the next section.

The competitive landscape

The landscape of ultra long power reserve wrist watches is not very large. Notable landmark watches include the Lange 31 (2007), the Jacob & Co. Quenttin Tourbillon (2006), the Hublot MP-05 LaFerrari (2014). All feature complex barrel systems and elaborate winding schemes to wind them. The Paneral 31 Giorni is a manageable size, uses only 4 barrels and can be easily wound from the crown. I manipulated the crown, and it was not more difficult to wind than a regular hand wound watch.

The Lange 31 had a case measuring 47mm, and at full power, will run for 31 days. To tame the giant mainspring within, Lange chose to use the elegant remontoir. This chops up the tremendous power reserve and its aggressive torque curve into 20s sections, with the balance running off the significantly more linear torque from the remointoir spring. To wind the watch, Lange provided a very beautifully crafted tool to overcome the winding torque and to reduce the number of turns needed to a manageable level.

The Jacob Quenttin Tourbillon was a handiwork of BNB Concepts, back when Matthias Buttet, Enrico Barbasini, and Michel Navas ran the company. This was a monstrous watch measuring 47mm x 56mm x 21.5mm. It had seven mainspring barrels, stacked horizontally across the upper half of the case. A lever flipped up from the thick side, and turning this lever 200 (!) times would fully wind the barrels.

Hublot’s MP-05 La Ferrari currently holds the record for being able to run autonomously for 50 days. It had eleven barrels and also feature a tourbillon. To wind the watch, Hublot provides an electric drill device which connects to the crown.

Then there was the Rebellion. They proposed several watches with ultra long power reserves – T2M (2-Month Power Reserve): This model boasts an incredible 1,400-hour power reserve, equivalent to about 2 months, by using 8 vertically mounted barrels, the T-1000: This model offers a 1,000+ hour power reserve (more than 40 days) generated by six mainspring barrels, the Prometheus T3K: Features the same T1000 movement, offering 1,000 hours of power in an open-worked case design, the T-500: Features 450 hours of power, styled after racing machines. All feature an integrated lever to wind the barrels. We did run an article of it from the early days (apologies for the lost images), but as far as we can tell Rebellion has ceased operations, and it is our understanding that none of the watches they proposed ever worked properly. Tell us if you know otherwise.

Concluding thoughts

The Luminor 31 Giorni is a rather beautiful timepiece. It looks no different from any other skeletonised 44mm Luminor. Yet, within, it hides a monster movement capable of running accurately for 31 days. This is quite an achievement, especially for one that is packed this small, and does not require elaborate methods or tools to completely wind the watch. Our Competitive Landscape above explores this ultra long power reserve watches, and in this company, the Panerai stands alone.

Panerai Luminor 31 Giorni PAM01631 Specifications

Movement: Hand would, P.2031/S calibre, 15 ¾ lignes, 10.06mm thick, 25 jewels, 21,600 alternations/hour, Glucydur® balance, Incabloc® anti-shock device, four barrels with torque limiter, stop balance wheel, movement automatic stop. 276 components.

Functions: Hours, minutes, small seconds, patented polarized date, power reserve indicator.

Power Reserve: 31 days (744 hours).

Case: 44mm, brushed Panerai Goldtech™ case and polished bezel. Screwed see-through sapphire crystal case-back. Sapphire crystal.

Rehaut: Skeletonized structure with 12 and 6 numerals applied on the rehaut. Indexes and hands finished with white Super-LumiNova® X2. Polarized date disc visible through the 3 o’clock window. Power reserve indicator. Small seconds sub-dial at 9 o’clock.

Strap: Black alligator strap, Panerai Goldtech™ folding clasp with PAM Click Release System™. Additional black rubber strap.

Packaging: Deluxe cherry blue wood box comprising an additional black rubber strap.

Water resistance: 10 bar (~100 meters).

Limited edition of 200 pieces