Hey guys just saw this sea wolf on ebay. item 110808434902. It seems as if the movement says 72b and seventeen jewels......Is this possible? I always thought 72b was 21 jewels.
Whats the difference? I own the exact same watch and movement and mine is a 72b  21 jwl.

Thanks.

FYI getting my orange sea wolf back from shop in couple weeks. I found a mint 72b movement, mine had rusted a little bit and a NOS orange/black dial as mine was pretty faded. I cant wait to see it back to original glory.

Funny thing that. Over the years I have seen most of the Zodiac calibers in both 17 and 21 jewels. A quick look at one of the service manuals on ZodiacCatalogs.com does not even mention the jewel count for each caliber. I imagine that the 4 additional jewels are located in the rotor assembly though as the rotor has the jewel count on it.

UV, do you know the rhyme or reason why there was a 17 and 21 jewels version of the 72, 88, etc.? And where the extra jewels are and what their function is?

I do know that later jewel count became the big selling point though and they sold 50 and even 100 jewel movements, but most of them were non-functional, just justifying the counts. I also think that one does not want a watch with less than 15 jewels too. I have one very old Zodiac with 7 jewels, but that was the time for that sort of thing.

You hit the nail on the head Butch.  The main difference between the Zodiac 72 movement family's 17 and 21 Jewel automatics is the jewelling of the automatic assembly and the parts that transfer that motion into the winding components of the movement.  The automatic assembly of the 17 Jewel movement has brass settings (for the reverser wheels etc), and when you have metal pivots in brass settings, the pivots can over time wear the setting out of round.  The synthetic jewels allow for durability, less friction, and can be easily replaced if the setting is damaged.

Zodiac was actually ahead of many of the other Swiss companies, as quite a few of them still used 15 - 17 jewel movements with added non-jewelled automatic rotor assemblies.  It was more commonly found on expensive brands at the time that Zodiac thought it was important to update and make their movement higher grade.

I too have seen both 17 jewel and 21 jewel Sea Wolfs. I have always assumed the jewel count depended on where the watch was sold. If it was sold in the US, it had 17 jewels and sold elsewhere, it had 21. At one time the US had a high import tax on watches with more than 17 jewels. This may or may not be the case for Zodiacs. I do know for certain it holds true for some other watches sold in the 60's. I have a Glycine Airman with the original 1967 sales receipt sold in a PX in Asia. It has a 21 jewel movement. The ones sold stateside even in the PX's had 17 jewel movements.
Best,
dmh 

Thanks guys!