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Author PDR

Seiko SBBN007 “Tuna Can” Review & fitting Watchadoo Bracelet

Following my recent purchase of a Seiko SBBN007 I thought it might be useful if I where to share with others my experiences. There are numerous posts about these watches spread across several different forums and it took quite a bit of searching to find answers to my own questions regarding this watch and the fitting of various straps and the Watchadoo bracelet.

I ordered the watch, bracelet and spring-bars all at the same time (from different sources).

The watch
The model, to give its full title is Seiko SBBN007 Seiko Prospex Marine Master Professional 300 Meter Diver. It may also be referred to as the “Tuna Can” or “Shrouded diver”. It is a Japan only model so not officially available here in the UK.

Supplied by price is $450 / £238

Movement is Seiko quartz, calibre 7C46 with 5 year battery life and an end of life indicator.

There is no getting away from the fact that is a big watch, the dimensions are:

47mm dia. x 14.4 mm thick. 44 mm lug to lug, with a 22 mm lug spacing.
Weight (without strap/bracelet) 92.3 grams. Case is stainless steel with sandblasted finish shroud held in place via four stainless screws.

The lume
Lumibrite is used on the hands and dial and I must say that I am very impressed with the quality. I have found that by shining one of my Surefire torches (fitted with a 19 lumen LED head) at the dial for 20-30 seconds before I go to bed, that the lume will shine for about 7 – 8 hours. The luminous triangle at 12 o’clock can be clearly seen, however if you have poor eyesight then I’m sure the fact that there is no lume in the 3 o’clock (day/date) position will help in quickly orientating the watch so as to read the correct time.

(This is my first attempt at a lume shot…I will try for a better photo later)

Watch / wrist size
I have read a fair number of posts where people have expressed concerns over the size of this watch and whether it might be too big for their wrist. I have approximately a 7 inch wrist and I don’t have any problem with the size of the watch and no one has passed any negative comments. The lug to lug length is only 44 mm which is about 3 mm less than what you would typically find on a normal 38 mm diameter watch. Because of this the spring-bars are hidden when looking down on the watch with only the lug tips visible from the edge of the 47 mm shroud.

Drilled lug
One of each pair of lugs is drilled all the way through which makes strap changes very easy. You just push a watch tool or even the end of a straightened (giant) paper-clip through the hole...

There is a lot of talk about Seiko “fat” spring-bars on the forums but rarely does anyone mention their diameter. I have found with the aid of my digital callipers that they are in fact 2.5 mm in diameter.

I ordered two sets of 22 mm spring-bars in 1.5 and 2 mm sizes. The 1.5 mm version (from e-bay) where too thin and fell out of the drilled lug. The 2 mm heavy weight spring bars (from RTL) where a much better fit. I didn’t have any (22mm) 1.75 dia Spring-bars to try.

Seiko dive strap
Weight 25.5 grams. Watch & strap combined 117.9 grams.

The standard strap fitted to this watch looks identical to other Seiko offerings but is in fact made from a different material called DALOAZ it is manufactured in Japan and is much more compliant than the standard rubber versions. They are long enough to be accommodate the extra thickness of wetsuits. I was very surprised at how comfortable it is to wear even in the hot environment in which I work.

Nylon strap
Weight 20.1 grams. Watch & strap combined 112.3 grams.

This strap came along as a complementary gift from “Watchadoo”. It is heavy duty “2 ring” and similar to the “rhino” straps. It would not fit using the Seiko “fat” spring bars, but I was able to get it on using the 2 mm spring bars even though it was a bit of a struggle. The watch sits a bit too high and awkward on this strap for my liking (might be because it was new). A thinner NATO may be better?

Watchadoo Bracelet
86.3 grams (sized to my wrist). Watch & bracelet combined 178.8 grams.

These bracelets seem to have quite a cult following on several forums. Often referred to as “lumpy”, they are available from an e-bay seller in Australia. I’m not sure where they are made, but you can’t fault the quality. There are usually three different sizes available, 18, 20 and 22 mm and they come in polished, brushed or sand-blast finish. Guide price for “buy it now” is $50 / £26. The 20 and 22 mm versions are virtually the same except that the 22 mm bracelet starts to taper from 20 mm to 22 mm 2 links back from the end pieces. The spring bar hole in the end pieces seems to be drilled for 1.75 mm spring bars. These are heavy bracelets with solid, well fitting links which do not rattle like some cheap bracelets. They have a double button side release and safety clasp. I have found it to be very comfortable to wear.

When buying from Watchadoo, it might be worth mentioning that you intend to fit the strap to a Seiko driver as he apparently has some suitable spring bars available.

Seiko Bracelet

At least one dealer, is now offering this watch on a Seiko bracelet with diver’s extension. Model # SBBN007J-6. Priced at $538 / £285

Black bezel

A common modification seems to be the fitting of a black bezel insert as found on other Seiko divers such as the SKX007.There are several tutorials around on doing this mod but I have not sort permission to post a link. This conversion appears to be straight-forward, however it might be worth noting that the original sliver bezel is both difficult to find and expensive to buy. I did consider doing this mod myself but I have decided against it for the time-being. If the original bezel starts to get really battered I’ll then think about doing this mod. The numbers on the original sliver bezel insert are recessed and filled with black paint, (so should be restorable along with the bezel its self), whereas the black bezel insert has the sliver numbers printed on (much more prone to wear?). Another option is the Yao (MKII Watches) “Steel GMT insert”.

On the subject of wear & tear, I imagine that there are several people around who could bead-blast the shroud to restore a near original appearance. I have already mentioned the bezel so this just leaves the crystal as an area that might become damaged. I don’t know where or how you would go about replacing these substantial crystals so it is probably best to try and avoid scratching it in the first place, which is where the next subject comes in…..

Crystal protector

I‘d hate to put scratches into the crystal of this watch and I began to wonder if there might be anything like the protective film you see for the screens of PDA’s and smart-phones that would be suitable for watches….. the answer is yes!

I found some clear PVC “watch guard / protectors” on e-bay (seller named watch_bits) £4.75. They come in different sizes so you need to measure your crystal. They adhere to the crystal with just suction (no glue). I’ve been trying one out for the last few days and it seems to be working very well. Yes, they will come off if you blast your watch under the water tap and probably if your diving too… but for day to day tasks they are fine and if they stop the crystal getting scratched then I’ll be very pleased. After all it is daily wear that tends to cause the damage rather than the odd diving session.


The battery lasts for five years and there should be a mark on the case-back indicting when this is due. It seems that the watch should be sent back to Japan for a battery change, there is a coupon for a free replacement in the manual accompanying the watch. T may be possible that forum members (here n the UK) might e able to change the battery rather than send the watch back to Japan? Apparently you need the “L” shaped gasket for the case back.

Fitting the Watchadoo Bracelet

I chose the 22 mm brushed version of the Watchadoo bracelet for my SBBN007.

I had to file the end-pieces down so that they would fit the watch lugs. This was easy enough and didn’t take too long. The next part was the spring bars. As I mentioned earlier, I only had 1.5 & 2 mm spring-bars whereas the Warchadoo bracelet is drilled for 1.75 mm spring bars (I had some in 20 mm to test). The only thing to do was to drill the holes bigger! I bought several packs of drill bits in 2 mm earlier that day. Holding the bracelet in the Black and Decker “workmate” I took a small hand drill and proceeded to slowly drill out the holes. Yes of course I snapped a drill bit, but as long as you know which side you where drilling from, you can knock the piece back out (I used a 1.5 hex mini screw-diver). I actually managed to get the holes nice and strait. Some people have apparently been able to drill these end-pieces out to accept the 2.5 mm Seiko “fat” spring bars, though I rather not try it myself just yet.

I needed to take out a few links in order to size the bracelet to my wrist. To do this you need to knock or push out the pins in the direction of the arrows (replace them back through the same side came out). I used an old broken 1mm drill bit and small hammer to drift out the split pins with the bracelet posited over a small hole in the work bench. All together it took a couple of hours work, but I am very pleased with the result.

I do know of at least one person who has changed the clasp for a genuine 20mm Seiko version. There is nothing wrong with the standard, unsigned clasp, but there is no denying that the Seiko version looks better.

I know the photos could be better but hopefully they will serve to illustrate the various points.

I really like this combination and I’d say that it has the look and feel of a watch costing considerably more than the price it cost.

I hope this compilation of Seiko SBBN007 topics is of use to other readers.

Paul D. Rowley.
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