SLA023 vs SLA047
Geth put them head to head in "Seiko Marinemaster 300. SLA023 SLA047". Scores, specs and verdicts side by side.
Seiko SLA023 Marinemaster 300
His grail and favourite Marinemaster: an unmatched Zaratsu case, the best bezel action and handset he's ever known and Christmas-tree lume. The Prospex X, the painted triangle and the unregulated movement are the only things stopping it being perfect.
Seiko SLA047 'Island Green'
His favourite watch case ever on a British-racing-green dial, with buttery bezel action, his favourite handset and mental lume. He can't choose between it and his SLA023, and only the painted triangle worries him.
Too close to call
I couldn't choose between the two: they both look amazing, and they're my favourite watches ever. The only glaring flaw is the unregulated 8L35, though both of these run within plus five a day.
Spec sheets
| SLA023 | SLA047 | |
|---|---|---|
| case diameter (mm) | 44.3 | 44.3 |
| thickness (mm) | 15.4 | 15.4 |
| lug to lug (mm) | 50 | 50.5 |
| lug width (mm) | 20 | 20 |
| weight (g) | 222 g with all links (about 205 g with a link out each side), said of both MM300s stated by gethin | 222 g with all links stated by gethin |
| case material | 316L stainless steel ('I believe') with Diashield coating (about 500 Vickers vs 250), duller and greyer than the SBDX001; monocoque case, brushed midcase, Zaratsu polish on the top of the flanks, drilled lugs | Stainless steel (316L 'I believe', said of the SLA023 in the same video); monocoque case; brushed lug tops and midcase, Zaratsu polish on the top of the flanks only, drilled lugs |
| crystal | Flat sapphire with an internal dome (AR coating inside) | Sapphire, AR coated, internal dome |
| water resistance (m) | 300 | 300 |
| crown | Screw-down, signed (laser-etched 'Prospex X'), at 4 o'clock | Screw-down, at about ten to four; etched Prospex X crown he dislikes |
| caseback | Monocoque, no removable caseback; tsunami wave on the back. Not limited. His is a March 2021 J1 | Monocoque, no removable caseback. Mr Jun's is a November 2020 piece |
| bezel | 120-click unidirectional, ceramic insert, coin-edged; unprotected painted lume triangle instead of a shrouded pip, lumed to the 20-minute marker. His has a dent from a car seatbelt buckle; Seiko quoted GBP 500 for a replacement bezel. In the Jan 2023 strap video he also says it is 'slightly misaligned' | 120-click unidirectional (said of the SLA023's identical bezel), black zirconia ceramic insert ('1200 Vickers'), lumed to the 20-minute marker; painted, unprotected lume triangle rather than a shrouded pip. Turns slightly stiffer than his SLA023 |
| dial | Navy blue sunburst: almost black indoors, bright sunburst in sunlight; gold seconds hand (lumed lollipop) and gold '300m' text; indices look applied but he hears they are stamped from the back; Prospex X on dial; ISO sliver/marking near 3 o'clock on post-March 2021 examples like his | Inky green; Seiko calls it Island Green, he calls it British racing green; looks black in low light |
| date | Yes, at about 4:30 (date window with a sliver, per hOuORgMFkZ8) | Yes; date window with a sliver (said of both MM300s in hOuORgMFkZ8) |
| movement | Seiko 8L35B, 26 jewels, 28,800 vph, hacking and hand-winding, 50 h power reserve, based on the 9S55, about 192 parts, hand assembled at the Shizukuishi studio, MEMS escapement parts, SPRON springs; rated +15/-10 s/day, not regulated. His has run about +2 to +6 s/day across videos | Seiko 8L35B, 26 jewels, 28,800 vph, hacking and hand-winding, 50 h power reserve, based on the 9S55; hand assembled, MEMS pallet fork and escape wheel, rhodium-plated bridges and rotor, SPRON springs; rated -10/+15 s/day, not regulated. Mr Jun's ran at about +1 |
