Alpina’s Seastrong Diver 300, Hamilton’s Khaki Navy Frogman and Davosa’s Apnea Diver Automatic love to dive, but today they’re at a swimming pool. In this comparative review from WatchTime’s March-April 2018 issue, we test these three sporty dive watches to see how they perform swimming laps and jumping from diving boards.
Even a quick glance at Davosa’s unconventional Apnea Diver Automatic, one of the few watches specifically designed for free divers, makes it clear that this extremely athletic pursuit not only demands peak physical performance but also self-confidence and self-reflection.
Like the Apnea, the extroverted 2016 edition of the Khaki Navy Frogman was developed in collaboration with a world-renowned apnea diver. In all other respects, however, the current edition of this Hamilton watch pays homage to the divers’ watch that appeared in the 1951 movie, The Frogmen, and became the first Hamilton watch to grace the silver screen. And last but certainly not least, Alpina’s Seastrong Diver 300 is also influenced by history but is much more understated in its styling. This model is the direct descendant of the Seastrong 10 from the 1960s, which was watertight to 200 meters when it first debuted.
The current Seastrong is watertight to 300 meters, which brings up an “old” debate. The misconception that the phrase “watertight to xxx meters” specifies the depth to which a watch can safely descend is widely circulated and persistent. And since almost no one dives to a depth of 300 meters, a watch that’s labeled “watertight to 30 meters” would seem to be suitable for diving 30 meters below the surface. But this assumption is totally wrong. In some countries, a relevant legal verdict now prohibits watch manufacturers from specifying the depth of water tightness in meters only. The real water tightness depends on the amount of water pressure the watch withstood in a water-tightness test. For the Seastrong 300, this means 30 bar, i.e., the amount of pressure exerted by a 300-meter-tall column of water or at a depth of 300 meters below the surface: hence, the specification in meters.
The depth in meters is printed on the Seastrong’s dial, while the corresponding pressure in bar or ATM (atmospheres) is engraved on the caseback. All three watches in our test are watertight but to different depths. The Davosa is watertight to 200 meters, i.e., pressure resistant to 20 bar. The Hamilton can descend even deeper: it stays watertight to 1,000 meters, i.e., pressure resistant to 100 bar. Each of these three watches can come along for a dive and also accompany its wearer for a dip in a swimming pool. Unlike timepieces that are watertight only to 30 meters, i.e., pressure resistant to three bar, these watches can withstand the impact of water spraying from a showerhead or from a Jacuzzi’s massage jet just as easily as they can cope with a powerful freestyle swimming stroke or a leap headfirst from a starting block into a 50-meter pool.
If you’d like to swim those 50 meters underwater on a single breath of air, then the Apnea Diver Automatic would be a good choice because the colored arcs on the seconds scale around the rim of the dial make it easier to train yourself to hold your breath and measure your progress. This scale is calibrated according to the globally agreed-upon plan for free diving: 5 seconds of inhalation (shown in blue), followed by 15 seconds of holding your breath (the white arc), and finally 10 seconds of exhalation (indicated in red). And Davosa has dreamed up a convenient mechanism for training on dry land: if you unscrew the crown at 3 o’clock, you can remove the main case from its container, flip open a hinged ring and stand the timepiece on a desktop like a miniature table clock. Freediver Nik Linder also integrated another practical detail into the Davosa’s Apnea: minutes play the decisive role for scuba divers, but seconds are crucial for apnea divers. That’s why the seconds hand on this watch culminates in an elongated red tip that extends across and sweeps unmistakably along the seconds scale.
A long red tip also defines the business end of the seconds hand on the Khaki Navy Frogman, which was designed in collaboration with apnea diver Pierre Frolla. But unlike the Davosa model, the Frogman is suitable for many diving-related purposes, thanks to the minutes calibrations for scuba divers on its rotatable bezel, pressure resistance to 100 bar for dives to great depths, and an automatic helium-release valve for saturation diving. The Frogman blithely survived a jump from a 10-meter tower, and the protected, canteen-style crown also withstood a hard smack against the edge of the pool. But the large crown guard, which is adapted from the one on this watch’s predecessor from 1951, makes it a bit cumbersome to operate the comparatively tiny crown underneath the protector.
The operating elements of our other two test watches are screwed down. Handling the Davosa’s crown is demanding because of its position at 12 o’clock and the rigid container underneath. The crown on the Alpina Seastrong has a rubber ring and is easy to grasp, unscrew, operate, and screw shut again. The Seastrong is fine for swimming in a pool, but it lacks a few details that would qualify it as a professional divers’ watch: for example, an illuminated seconds hand to instantly con rm that the watch is still running and single-minute calibrations along the entire rotatable bezel. To give credit where credit is due, all of the Seastrong’s scales are completely luminous, a detail that is rarely seen on divers’ watches. The downsides are that the hour hand and the minutes hand aren’t easy to tell apart in the dark, and single-minute calibrations are lacking on the dial and on two-thirds of the rotatable bezel. For wearers of this watch, this means you can swim a few leisurely laps in the pool and maybe preset your intended swimming time with the aid of the rotatable divers’ bezel. Or perhaps just chill at poolside or recline in a chaise longue on the lawn nearby.
Diving is no problem for Davosa’s Apnea. Its luminous double-digit numbers, bold indexes, and broad hands are clearly visible, even while swimming along the bottom of the pool’s deep end. The numerals, indexes, and hands on Hamilton’s Khaki Navy Frogman also glow at great depths and in a beautiful shade of blue. When you come up for air, you’ll find Alpina’s Seastrong Diver 300 waiting for you in the sunshine. This watch recently changed its outfit: it has been available with a stainless-steel bracelet since 2017, but the tripartite construction of the double folding clasp has neither a divers’ extension nor a safety bracket. The rubber straps of all three watches we tested also lack these features, so they’re OK for swimming, but not ideal for professional diving.
Despite its nearly 45-mm-diameter stainless-steel case, the Alpina looks comparatively unpretentious. It’s also the only one in our trio with a transparent caseback, through which an aficionado can admire Sellita-based automatic Caliber AL-525. This movement is equipped with a special rotor and gives its best timekeeping performance when on its wearer’s wrist. The same basic caliber inside the Davosa’s case exhibits somewhat different rate behavior: it runs better overall, but it’s not well balanced. And it’s concealed behind a massive, fully threaded, screw-in back, which hermetically seals the nearly 43-mm-diameter stainless-steel case. The container enlarges the overall diameter of this watch to a hefty 46-mm so it makes a more massive impression. Immobile lugs and the tall construction of the case mean that this watch needs to be worn on an amply sized wrist.
Hamilton’s Frogman is also made for people with big wrists. The titanium case isn’t only an impressively large 47.5 mm in diameter, but it’s also rather tall. It spreads a caliper’s jaws 16.12 mm. This height is part of the tribute demanded by pressure resistance to 100 bar. This watch is equipped with Caliber H-10, which is known as the “Powermatic 80” and is based on an ETA C07.611. As its name suggests, it amasses an 80-hour power reserve. It runs with quite well-balanced rate values, which it achieves while hidden behind a massive screwed case- back engraved with a diving motif.
While small improvements could be made in each of these three watches, Hamilton’s Frogman outdid its two competitors. It satisfies all the requirements of a divers’ watch with the exception of a safety bracket for the clasp and an extension mechanism to lengthen the strap. Davosa’s Apnea performed quite well; although it isn’t specifically designed for scuba diving, single-minute calibrations along its bezel would be a welcome addition. And Alpina’s Seastrong 300, a divers’ watch that continues this brand’s tradition, would benefit from a few modifications: the illumination and the calibrations are better on some of Alpina’s other models.
Alpina Seastrong Diver 300
Manufacturer: Alpina Watch International SA, Chemin de la Galaise 8, 1228 Plan-les-Ouates, Switzerland
Reference number: AL-525LBN4V6
Functions: Hours, minutes, central seconds, date, rotatable divers’ bezel, screwed crown
Movement: In-house AL-525 based on Sellita SW200, automatic, 28,800 vph, 38-hour power reserve, gilt nickel balance, Nivarox hairspring, Incabloc shock absorption, index bipartite (Etachron) fine adjustment, 26 jewels, diameter = 25.6 mm, height = 4.60 mm
Case: Stainless steel, sapphire crystal above the dial, sapphire crystal in back, water resistant to 300 m
Strap and clasp: Rubber with pin buckle
Rate results (deviation in seconds per 24 hours (Fully wound/after 24 hours)
Average rate: +9.3 / +7.6
On the wrist: +6.5
Dimensions: Diameter = 44.70 mm, height = 13.21 mm, weight = 122.0 g
Variations: With gray bezel; with rubber straps in various colors; with stainless- steel bracelet with folding clasp ($1,495)
Davosa Apnea Diver Automatic
Manufacturer: Davosa International, F.W. Bohle GmbH, Lönnsstrasse 7, 32602 Vlotho / Weser, Germany
Reference number: 16156855
Functions: Hours, minutes, central seconds, rotatable divers’ bezel, screwed crown, removable case container
Movement: Sellita SW200, automatic, 28,800 vph, 38-hour power reserve, gilt nickel balance, Nivarox hairspring, Incabloc shock absorption, index bipartite (Etachron) fine adjustment, 26 jewels, diameter = 25.6 mm, height = 4.60 mm
Case: Stainless steel and ceramic, sapphire crystal above the dial, water resistant to 200 m
Strap and clasp: Rubber with pin buckle
Rate results (Deviation in seconds per 24 hours, Fully wound/after 24 hours):
Average rate: +5.3 / +0.6
On the wrist: +3.4
Dimensions: Diameter = 42.80-mm case (46.03-mm container), height = 12.33 mm, weight = 140.0 g
Variations: With various straps; with black PVD-plated case ($1,099)
Hamilton Khaki Navy Frogman
Manufacturer: Hamilton International AG, Mattenstrasse 149, 2503 Bienne, Switzerland
Reference number: H77805335
Functions: Hours, minutes, central seconds, date, rotatable divers’ bezel, screwed crown, helium valve
Movement: In-house H-10 based on ETA C07.611 (Powermatic 80), automatic, 21,600 vph, 80-hour
(>3 days) power reserve, Glucydur balance, Nivarox hairspring, Nivachoc shock absorption, fine adjustment via two screws on balance, 25 jewels, diameter = 25.6 mm, height = 4.60 mm
Case: Titanium, sapphire crystal with nonreflective treatment above the dial, water resistant to 1,000 m
Strap and clasp: Soft-touch rubber with titanium pin buckle
Rate results (Deviation in seconds per 24 hours (Fully wound/after 24 hours):
Average rate: +3.6 / +5.5
On the wrist: +1.2
Dimensions: Diameter = 47.51 mm, height = 16.12 mm, weight = 136.0 g
Variations: 42-mm version in stainless steel, water resistant to 300 m, with various rubber straps or stainless- steel bracelet with folding clasp ($1,095)