What the heck is this?

The little mono-rigged boats are 12 Voetsjoel (sp?) formerly the International 12. Designed by the UK's George Cockshott before WW1 and the first international dinghy class (declared international 1914 I think).

It was used for the 1920 Olympics (only two boats raced, both owned by the same man and the racing moved from Holland to Belgium or something halfway through the regatta, making for the most international of Olympics  :-)  ) and in the 1928 Games where they got a good fleet.

Still about 400 sailing in Holland, where only wooden planked boats are racing. A resurgence in Italy, which allows 'glass boats and has I think something like 150. Also a class in Japan.

If anyone tells you that (a) the Snipe, I 14 or Star were the first international one designs, point them to the 12 (b) that one designs die out, point out to them that the first 2 one design dinghies (from 1884 IIRC) and the first interntional OD (1912-ish) are all still sailing.

I think the bigger boats are Rainbows (Regenboogen) or 30 square metres (not the ex Int 30 square but a local class).