Thanks for looking Anne,
I have a theory why the section 8 is missing, I think the original design of the ship was to include a hoist similar to 3750. This part of the ship could possibly of been scrapped to keep the cost down.
My reason behind this is the circular part on the front mast which is designed for a turning wheel of some kind and the clip at the top of the sail could have an arm attached to it. So my theory is that part 8 was to show these parts being assembled to the mast.