The first picture looks like the boom end from the original windsurfer. So I'd say around 1979.
I say 20/08/2011 for all of them 
Second one- Hydrodynamix clamp in front like on the old Z booms about 1988 - 1993
Third one, first NeilPryde Matrix boom about 1992-1995
First one is from the Original Windsurfer, with the tie-on neck piece at the booms.
It seems to be a US model, not the Oz one, so would have to be real early before the Aus model. So no later than 1981-2 or so. And no earlier than 1980 - teak before !
I was using one of those boards just yesterday - there was little wind and I still wanted to get out...
