Hi Andrew,

I had just the same question, as my drawings (old style 39 sq ft sail) show the mast raked back about 3 degrees from vertical, yet the picture of the full rig (new style 42 sq ft sail) in the instructions manual shows the mast plumb vertical.

I spoke to a chap at Fyne Boat Kits, who sell CLC kits in the UK, and we agreed that getting the mast plumb vertical (or indeed at any exact rake angle) probably isn't as critical as the instructions imply. It's a small boat and moving body weight around will make considerably more difference to the angles and balance of the boat than a couple of degrees error in build anyway.

My conclusion was to get it perpendicular side to side, and raked aft a couple of degrees just because it looks right (and to avoid the possibility of it ending up raked it at all forward, which would look ugly)

As for the reference line - I wedged the boat so the centre thwart was horizontal (centreboard vertical) with a couple of spirit levels. I also checked the level transom to transom (not the top of each - again I measured one of the whole-boat drawings to get the correct relative height of the transom tops from the waterline. If you use sheet 2 of 7 (12/02/2002) note that the waterline drawn at the bow is at a different level to the waterline drawn at the stern!)

   Yeah, I came to the same conclusion (that it doesn't have to be precise and a slight rake aft is preferable to a slight rake forward). After looking at the plans for way too long I think that the lower edge of the skeg is supposed to be horizontal (parallel to the waterline), so I guess that's what I would use for the reference line.

I ran into the same issue, too, regarding mast step and gooseneck positioning on the boom.  It appears that changes going from Mark I standing lug to Mark II balanced lug were incompletely/inconsistently applied to the manual and drawings.  To complicate matters the full size plans I was sent had the bow section from the take-apart design.  Jay Hockenberry sent a "revised" mast step design that would have given mast significant forward rake. Fortunately I did not cut the partners hole before putting in the mast step so I was able to locate the parners and design a mast step that positioned the mast with a slight aft rake relative to the center thwart (how do you measure angles on a boat when the reference line isn't specified?). 

It is disappointing to pay for plans were there are so many errors and the builder must comb through forums and call the help line ("that's what the help line is for") to find the correct information, hopefully before any point of no return.  Doesn't say much for CLC attention to detail and gives one pause regarding what else is missing.