The sub-$400 diver's real fork in the road.

Twenty five dollars separates these two automatics at the low end of their street price bands, and that gap is the whole argument. Both hack, both hand wind, both wear a black dial under a diver’s bezel on a 22mm lug. Only one of them clears sapphire and a genuine 200 meters, and it is not the one most first time buyers reach for.

The SRPD55 is the SKX007’s spiritual replacement and it wears that reputation well: a 42.5mm case built for a bezel that looks the part, a day and date window the SKX never had, and Seiko’s 4R36 doing the work underneath. The Kamasu takes the same brief, in house F6922 movement, hacking and hand winding included, but spends its extra price, not its size, on the two things the Seiko skips. At 41.8mm by 12.8mm it is actually the smaller watch of the two, and what the money buys instead is a sapphire crystal in place of Hardlex, and a case rated to 200 meters instead of 100.

Every line below is a published specification, not an impression, and the bronze rule marks the side the specification favours. Where neither side wins, the row says so and stays quiet about it.

Is the Orient Kamasu worth $25 to $45 more than the Seiko SRPD55?

Yes, if that money is available to spend. Sapphire over Hardlex and 200 meters over 100 are not marginal upgrades, they are the two specs a diver’s watch actually leans on, and the Kamasu’s HypeScore total of 86 against the SRPD55’s 80 reflects the same gap. The Seiko is not a worse watch so much as a cheaper one, and at $280 to $350 it undercuts the Kamasu by more than either fan base likes to admit.

Does the Seiko 4R36 or the Orient F6922 keep better time?

Neither manufacturer publishes a head to head accuracy figure worth comparing here, and both movements hack and hand wind, a courtesy neither watch strictly owes you at this price. The reserve favours the Seiko on paper, 41 hours against approximately 40, though that hour will not change how either watch fits your week.

Is 100 meters of water resistance actually a problem on the SRPD55?

Not for swimming or diving in the way most owners will use it, 100 meters covers real water sport. It is a problem only if you specifically want the certified depth rating and the sapphire that usually comes with it, in which case the Kamasu’s 200 meters is the honest upgrade, not a marketing number.

Which one is the better first automatic?

The SRPD55. It is cheaper, it has the deeper mod and parts ecosystem of any watch in this price class, and a scratched Hardlex crystal is a cheaper mistake to make while you are still learning to live with a mechanical watch. Graduate to the Kamasu, or past it, once you know you want sapphire enough to pay for it.

Do either of these actually carry an ISO 6425 dive certification?

No. Neither Seiko nor Orient claims that testing regime for these references on their own product pages, and the Citizen Promaster NY0086 sells in the same street price band and does clear it. If a certified rating is the non negotiable, that is the watch to buy instead of either of these two.