Hmm... while I'm not 100% certain, I could have sworn I have seen this particular bracelet on IWCs sold in Japanese auctions before. I just looked at a few auctions in Japan with Yacht Clubs featuring an IWC bracelet, and while the clasp on most looks like yours, the bracelet itself was different. Here's an example:
So I first thought that the one on your Yacht Club may be from a different model.
The solution may be in the 1972 Nakahiro catalogue:
View attachment 1694035
It shows your Yacht Club Ref. 1811 in the lower left, with the bracelet I have shown from the auction. Above that is a different bracelet which looks pretty similar to yours. In the lower right corner is a text that translates to "Special SS bracelet ref. 9115 - Yacht Club / Ingenieur only - 21,000 Yen" (SS meaning "stainless steel", of course).
So this bracelet was an option on the Japanese market. Mystery solved, I think? Maybe someone else knows something else about this.
Click to expand...