36'4" overall, 10'6" beam, 4'9" draft and a displ. of 14,000.
The first of the 11 or 12 that were built, was finished in 1964. Like the Alden Challengers, the Mistral is a fiberglass hull and deck built at the Hallmatic Yard in the UK. Most were finished by Hallmatic(likely with glass cabins) but a few were finished elsewhere.
One was finished at the Poul Molich yard in Denmark, which finished several Challengers(including mine). And there is the clue in your photo, that this is in fact(most likely), the one finished in Denmark. I've never seen an Alden Mistral with what is often referred to as the 'Jaguar ports' which are the most recognizable design element on the Challengers. That port shape caught my eye in your first photo, and this second one shows it well.
I thought it was a Challenger until I saw the deeper full keel(4'9" vs 4'0" centerboard Challenger-very noticeable to me). I'll post it and this info on our owners website for these boats. Thanks!