Seiko SRP639K1 Definitive Review, get the real facts about this watch!

70KM of deserted beach, I'M HALF WAY! SEIKO BABY TUNA AUTOMATIC 24 JEWEL 200M DIVERS WATCH, part of the PROSPEX series of dive watches. "PROSPEX" IS SEIKOS "PROFESSIONAL SPECIFICATION LINE OF DIVING WATCHES.

The Seiko model 08SRP639 otherwise known unofficially as the "Baby Tuna".
Whilst a certified diving watch, no watch with a bezel is really suitable for beach activities. Sand will get into the bezel mechanics and definitely wear out over time the ratchet mechanism or whatever mechanism is being used to produce a one way movement. I found that my previous diving watches were all susceptible to this and required careful cleaning. These watches also accompanied me on countless caving trips and there, the mud was also a problem. For these types of activities a watch which is waterproof (doesn't need to be a diving certified watch) but reliable such as a Casio PROTREK would be a better bet if one isn't into cleaning their watch thoroughly IMHO.

The shroud on the baby Tuna is also a magnet for sand to jam up the bezel, so whilst I say the watch is hardcore, and it definitely is, just remember it's not for digging sand castles or getting caught up in big surf dumpers (well heck, no one wants to get dumped in the surf. It's a bit like Peli cases being known as indestructible (I own many) but they aren't kid proof LOL!

The big chunky bezel is appropriately detailed with the naturally attention grabbing colours of yellow against black. This color combination is easily noticed by the human eye. Plus YELLOW is the last color to fade out in the water at depth.

The time is easily read too from even glancing angles!

Recently my trusty dive watch started to fall apart (see below). Surfing the internet on a new watch finding mission, my parents, (watching me closely, I was on a family trip to their home) thought I was looking for a new watch- well I was but not really thinking about actually buying one as I was thinking if I have money to blow on a watch then maybe i should spend it on my business instead as my other watch was by definition still going strong, just looking a bit crap and less functional (and not functional for SCUBA anymore). On the insistence of my ageing mother before she loses it (my words not hers but hers were close to this) she wanted to give me something to make her feel good before she couldn't remember anything at all. (She's 85). Not without me behaving badly at this point (I was brought under control by the wise words of the wife) I relented and we went on a journey to indeed check the prices the old fashioned way. Lo and behold a watch was found to my liking and at a better than internet price from a real bricks and mortar store! This is the watch:

Seiko Divers watch 200 m, (air diving only, ie no saturation diving- there is no Helium escape valve system- If you ever wondered about this, then suffice it to say, Helium is such a small molecule it can get through the tiniest of spaces, past O-rings/seals (dependent of the type of O ring or seal used) of some diving watches- also used in leak detection in high vacuum systems such as electron microscopes. Electron microscopes feature special seals which are helium proof when correctly installed).

BCT in the field testing not one BUT 2 watches! The Seiko baby Tuna and the Casio PROTREK PRW3000-4B!

What is the REAL POWER RESERVE?????

The Seiko Baby Tuna is a super cool, super tough, hardcore watch. BUT This watch has a stated power reserve of approximately 36 hours NOT 41 hours as many so called reviews state, they are clearly copying what everyone else is saying. The 36 hours ("once fully wound"- also stated in the following booklet) comes directly from a Seiko booklet accompanying this watch titled: "Mechanical and Automatic Watches". In this booklet on page 10 there is an amendment to the text (Seiko have placed a correction on this page in the form of new piece of paper glued across the existing text, clearly stating that the 4R36 movement (3 hands with day date calendar) and discuss the accuracy of this movement (accurate to only +_ 25 seconds per day. I have found this to be the case in practical usage of this watch model. If you are wondering about where this booklet fits in, well it forms part of the guarantee/warranty booklet and at the back of it, it contains a small pocket to hold the official guarantee card.

Also see here this link to the official Seiko page regarding automatic watch maintenance:

READ THIS

Now I should say this is the International, Australian, New Zealand and South Pacific Islands Guarantee card, so the car you should get with this watch if you buy a genuine non grey market watch will be slightly different for your region. So you should also get an official watch booklet, like this too:

HOWEVER, the 4R36 movement doesn't change. Australians don't tell time differently to the rest of the world despite being down the bottom- or maybe there is a real difference!

Just in case you are wondering what was behind that bit of stuck in paper, it was text about changing batteries in analogue quartz watches!

This Seiko Diver's watch sports the infamous "Shroud", this model with a brushed stainless steel shroud. 24 Jewels, 4R36 movement 169 PARTS, that means hacking*, day date and manual winding capacity. There are 21,600 vibrations per hour with this calibre. Screw in big chunky grippy crown. The uni directional bezel can easily be turned with wet hands. Funky yellow and black face accent, professional in appearance, super easy to read in low light.

This PROSPEX MODEL MEANS professional no BS specifications to ISO 6425. Exactly what one needs for "trust your life" diving watches. BTW my trusty and still working despite loosing the bezel ISO Eco Drive 200m was a great diving watch, sadly not made anymore in the original slim design.

This Model , the crown can be wound manually and should indeed be if the watch has not been on an active arm for a period of at least 10 hours! Constantly moving the arm for 10 hours should keep it ticking away just fine but despite wearing it to bed (all my watches) ones arms are not exactly active during the whole night and thus the watch is not being wound. Also since I'm working on a keyboard a lot of the time the watch will not be wound properly either. If you notice it loosing time, then it must be manually wound and this model, first click (after unscrewing crown) the crown can be wound about 60 times to get that main spring really wound up. This in fact was what i had to do when i noticed the watch was loosing time quite badly. STOP! Don't rush off back to your dealer or send it away for a service, simply manually wind it. Once the watch has been properly wound the active wrist should keep it topped up. In fact the manual states for the 4R36 movement (day and date display) that if the watch was not working when it was received then it should be manually wound "sufficiently" Now it is keeping good time!

What did I have or rather still own?

A Citizen Eco Drive 200m Divers watch.

My old but trusty Citizen 200 m divers, screw in crown ISO certified blew the bezel the other day in the surf, after 16 years of saltwater action LOL! The watch now looks a bit woosy without that manly bezel LOL!

*(precise alignment of the second hand).

Seiko Baby Tuna Automatic 24 jewels 4R36 movement 169 parts 200m Divers watch. Note the infamous stainless steel semi symmetric shroud surrounding the watch casing and anchored via 3 Allen/socket head bolts.

The infamous "shroud" (which is fixed in place by three 1.5mmX25 socket head bolts) is supposed to act as a shock absorber but in no way shape or form is this information from Seiko. The "shroud" can not act in anyway as a shock absorber as it is directly connected to the watch casing, that's just internet rumour BS. Possibly the plastic shrouded Tuna can act as a shock absorber but that model is not being discussed here. The steel shroud can act however in protecting part of the bezel from a lateral impact and helping to reduce the chances of accidental (it won't hurt anyway) advancement of the bezel-which would, if you are a SCUBA diver and reading this, simply reduce your bottom time/change your dive plan as you would be aware with a uni directional bezel. There is zero argument that the presence of the shroud definitely gives this watch a heavy duty look. The undersurface of the shroud is nicely rounded and is extremely comfortable to wear 24/7.

Seiko's famous LUMIBRITE luminous paint.

Well this watch glows like it radioactive (it's not so don't worry!) and after about 30 seconds of strong light from say a LED torch, I can easily read a book for up to 6 hours in total darkness LOL!

Seiko's Lumibrite is exceptionally bright.

Here is an interesting effect which has not been spoken about as far as I know in any blogs or reviews about this watch. Notice in the image (above and the one below) the secondary reflection from the Lumibrite markers in this image. At this point, the secondary image is seen where there is a recess in the watch face and only serves to further accentuate the watch face during low light situations especially when the Lumibrite has been well-charged.

Diving watches are obsolete!!!

There is an argument that todays divers do not need to wear a diving watch or that diving watches are obsolete. Well i say BS! Let's face it if you can't work out your dives via the tables then you rely entirely upon a wrist diving diving computer then if that computer or your buddy's one dies then you are not going to be able to tell the time, sorry. It's called redundancy.
My overall take is that one can't really go past the ruggedness of a proper dive watch for ultimate toughness in the field (or can one??? See what follows........).

PROS AND CONS

THE Pros of this automatic watch:

A good calibre will keep that watch ticking just fine for years.

4R36 sits as a reliable calibre. Before anyone says automatics do not keep good time, then think again if you are not wearing them 24/7.

Never needs any kind of power storage battery/capacitor.

-10C to 60C operating range! (off the wrist!).

Can be repaired by skilled watchmakers even if water has entered.

The cons of this mechanical Automatic watch.

Dependent upon the watch, maybe susceptible to mechanical shock. The 4R36 calibre was modified to withstand a mechanical shock better than the 7S movement (apparently a lengthened slot in the 4R36 regulator pin) and or magnetic fields as low as 60 gauss (that's about your average fridge magnet and certainly no Nd magnet- in other words an automatic watch is susceptible to magnetic fields- conversely a quartz watch will be less susceptible but possibly more susceptible to strong electrical fields. SO the bottom line is learn to remove any watch before sticking your hands into electronic equipment as a basic safety procedure. I did this all the time working with Electron microscopes (not operating them-but servicing them mainly to avoid potential electric shock situations within the guts of them). Those of you with electronics expertise will already be saying: "Yep already do this"!

The yellow painted minute hand does not stand out enough in low light if the luminous markers are not glowing strongly. Why is this? The individual hour markers are big chunky Lumibrite (which is great) but the minute hand is also a "big" lot of luminous Lumibrite and the contrast between bright yellow paint and lumibrite in low light is not good. A better accent colour would have been fluorescent orange instead of yellow (like Citizen do on their professional divers watches). for both hour hand and minute hand. Hopefully this will filter back to Seiko. BTW some trivia, the yellow paint fluoresces bright fluorescent orange under violet light!! So no wonder it looks so vibrant under the sun light. Some diver's flashlights have UV LEDs this will enhance the readability of the watch bezel UW.

Automatic watches can never keep time as good as a quartz watch. Although if worn constantly then good time is achievable. Luckily this watch can be hand wound and if not worn on an active wrist ie the wrist has not been active for at least ten hours then within the 40 odd hour power reserve time, this watch should be hand wound in order to keep good time.

Anyway check out the field testing!

NOW WHAT??????!!!!!!!

A Protrek Casio.....