I am not understanding. The photo shown does not depict a reduction unit with any gain in purchase, it just tracks to make the effort go with body weight.
The 3:1 purchase is at the head of the sail, therefore the tension on the line shown in the photo is 1/3 of the tension on the jib.
So, this is nothing to do with mast rake, just jib tension or is the mast loose like on a Windrush 14 and the mast can be bent forward by putting pressure on the bridle ring but in the case the jib pulley?
No, this has everything to do with mast rake. On a Hobie 16, the wire sewn into the jib luff
is the forestay when the jib is hoisted. The amount of jib halyard tension controls the amount of mast rake.
