It is no secret that we like (Grand) Seiko here on Fratello. From the low cost mechanical watches till the Grand Seiko models with Spring Drive movement. It is also no secret that we (well, especially me) are no fan of some of the bracelets that come on these watches. It is mainly the appearance that bothers me, not the build quality. In short, I was looking for a nice alternative for one of my favorite go-to watches, the Seiko Marinemaster 300.

Seiko Marinemaster 300

There are a couple of articles and reviews on that Seiko Marinemaster Professional 300 on Fratello, the latest one being the 52Mondayz feature from Gerard, where he talks about the watch he will be wearing that week. The current Marinemaster 300 is reference SBDX017, which is a slightly upgraded iteration of the reference SBDX001. A number of technical aspects changed in the latest version, but what did not change was the bracelet and the rubber strap that comes with it. A beautiful waffle strap that shows resemblance with the strap on the original 6159-7000 (1968). However, I found the rubber waffle strap to be quite stiff, and even after having owned the watch for over two years, it didn’t become more supple. It was time to take a look on the strap market, to see what’s there.

Seiko MM300

Crafter Blue

I’ve tried a couple of straps on the Seiko Marinemaster, from leather to other 3rd party rubber straps. But the watch looks best on the waffle strap or on the original stainless steel bracelet. Meet Crafter Blue! By coincidence I bumped into this company in Hong Kong when I searched the interwebs for a fitting strap.

The director of Crafter Blue, Steve Chan, explained me that they believe that Seiko watches deserve a better strap. As simple is that, and I agree. Although ‘better’ can be explained in many different ways, at least the design and comfort could be done better when it comes to the rubber waffle strap. I should add that the silicone straps that Seiko uses for their watches (including some Prospex models) are awesome and I actually use one for my Seiko 6159-7010 ‘Grandfather Tuna’.

Crafter Blue CB03 Black

Crafter Blue has ‘generic’ 22mm straps that will fit any Seiko with this lug width, with a design that looks familiar to the famous Isofrane strap. Besides that, they produce a number of straps specifically for a couple of Seiko models. The CB02 is a strap that will fit the Seiko Sumo perfectly, while their CB05 (above) is made for the well known SKX series of Seiko.

Crafter Blue CB03 Marinemaster Strap

I found that Crafter Blue has a strap they refer to as ‘CB03’, especially designed for the Seiko Marinemaster 300. Available in a variety of colors (black, brown, orange and yellow). Although I am Dutch, I went for the black rubber CB03 strap.

Crafter Blue CB03

This pure vulcanized rubber Crafter Blue strap comes without a clasp or folding buckle. Instead, you need to attach it to the original metal folding clasp from the bracelet that comes with the Seiko Marinemaster SBDX001 and SBDX017. A very easy task to do by the way, just use a Bergeon (or other make) tool to remove the clasp from the stainless steel bracelet and attach it to the rubber CB03 strap. The strap comes in a standard length (62.5mm + 100mm) and will fit any wrist up to 20cm (or 7.8 inch). This means that you will need to cut the strap to the desired length. The strap already has some ‘measuring’ grooves, so you can easily cut through it. Next, you need to attach the folding clasp to the rubber Crafter Blue strap. Again, use a proper to do these kind of tasks.

Crafter Blue CB03 brown strap

Image by Crafter Blue

Perfect Fit

I can tell you that wearing my Seiko Marinemaster 300 with this Crafter Blue CB03 strap is a great relief. Not only is it a good looking strap in my opinion, with curved ends that fit perfectly to the case, but it is also a very comfortable soft rubber strap to wear. Not too soft (it isn’t silicone as used on the Marinemaster 1000 models), but certainly not too stiff or uncomfortable like the rubber waffle strap.

Crafter Blue CB03

The clasp works perfectly on the strap, although I don’t find the clasp to be very pretty. You can resize the clasp in case you want to wear it over your neoprene diving suit or when your wrists are a bit swollen due to hot and humid weather. To do this, you pull the flip lock towards the rubber strap which releases the lock to slide the extension part of the clasp. Some times this is annoying, as when you want to remove the watch from your wrist, you have to use the flip lock as well of course. If you pull it a bit too hard, the clasp extension starts to slide. I already found this annoying on the stainless steel bracelet, so it doesn’t have anything to do with the strap. However, I wouldn’t mind if Crafter Blue comes with a normal buckle for their Marinemaster CB03 strap, like the CB05 I pictured above.

Crafter Blue CB03

Verdict and Pricing

As you probably already have guessed, I found the Crafter Blue CB03 to be a good companion for my Seiko Marinemaster 300. Easy to install, perfect fit between the lugs and the curved ends are nicely done as well. I am not a fan of the clasp, but it does work fine and fits well to the strap. Cutting the strap was an easy task, but there’s a little risk in cutting away too much material. So please be very careful with this and try to do this in a couple of steps so you find the right groove to cut. Once you are all set, the strap really is a joy to wear (and admire). Since I’ve put it on the Marinemaster, I didn’t feel like switching to a different strap again (I stay very loyal to straps that fit and feel good). I will also replace the standard strap on my SKX007 with the CB05 and get back to you in the near future on that one.

One thing that needs to be said is that the strap has a very strong scent. The other two straps I received from Crafter Blue suffer from the same strong scent. It took quite a while before it became less, but didn’t disappear entirely. Even after wearing the watch a couple of times, the scent seems to stick to the strap. Some rubber straps that I have (from other makes) are impregnated with this vanilla scent, which I can imagine would be a good thing to do if all Crafter Blue straps have this scent. Anyway, a minor issue and perhaps not applicable to all Crafter Blue straps, it is just that the three straps I received suffer from this. It didn’t make me NOT wear the Marinemaster 300 of course.

The price of the CB03 strap for the Marinemaster is $75 USD. Their cheapest strap is $50 USD. A 12 month warranty is given as well as a 7-day return policy.

Ordering and more information on Crafter Blue can be found here.

Interesting for those who have a Seiko Turtle, Crafter Blue will also have a special rubber strap for these models. Pre-orders will start soon and delivery is expected to be in August. Watch out for the Crafter Blue CB08 strap.

Robert-Jan Broer
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Robert-Jan Broer

Founder & Editor at Fratello Watches
Robert-Jan Broer, born in 1977, watch collector and author on watches for over a decade. Founder of Fratello Watches in 2004.
Robert-Jan Broer
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  • Mike V

    Crafter Blue makes nice straps. Their Isofrane style strap works great in the summer allowing air to ventilate where as the solid rubber straps are just too hot. Using the fitted ends on their Isofrane style strap would be an instant winner.

  • Chester Snapdragon McPhisticuf

    What is your issue with the vanilla scent? These straps don’t “suffer” from it. Many see it as a desirable trait that you can only get from real vulcanized rubber and as a sign of quality and authenticity.

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