: I read a step-by-step account posted by someone who built a Pygmy Osprey from
: a kit. Upon checking the vessel for trueness, he said it was within a
: thousandth of an inch over the entire length.

: How did he determine that????

he would not know as there are no measurable 3d plans available to allow him to say that for the boat 'along it's full length'. let alone be able to construct it that way. my building error on s&g per panel is abt 1/32” (abt .030”) let alone put together. for the boats prob abt 1/8”(if i’m lucky)

: Someone mentioned a laser level. A quick search on the net turned up a huge
: price range ($20 to $500). Are accurate ones available for rent? I don't
: want to buy one just for a one-time task. What alternatives for checking
: alignment are there, besides eyeballing the boat? (Yes, I am a total
: rookie at making anything.)

if it was fairly possible to set up an accurate(hopefully cheap) laser spinning vertically overhead say at the yak ctr to illuminate the whole keel line on a s&g, prob can get alignment and twist at the same time on a simple panelled hull.

{{other ideas:
one approach is to place/clamp multiple (4 or how ever many you wish) ‘winding sticks’ across the sheer along the yak, but have their ctrlines marked also(or mark symm from the ctr so can place down centrally or those 2 way 1/2size rulers). that way you can ‘eye’ for alignment AND twist

i would possibly just jam a stringline just betw the 2bow panels from the upper bow to the upper stern 2 panels(maybe use weights one end to allow for changes) and 1 or 2 more as far down as possible betw the panels(don’t have to be level) - one could even be 1-2” above the keel.(1/2in holes(or lgr if not sure where) needed in forms & b/h(temp)). if there is any discrepancy in alignment betw any of them and the keel line viewed from above, you automatically would know you have twist or alignment problems and where they are. use thin string and leave it in during the whole process - cut them off just at glassing. simple, cheap, helps exaggerate inconsistencies, is always there for fresh eyes of yr neighbors. (i showed a diff type of s&g kayak in progress to 2 paddling buddies last wkend and i could just FEEL them eyeing up the stringlines and forms etc and ‘seeing’ where i was not as careful as i should have been.)

from the upper string, side to ctr beam measurements could be taken anywhere along the yak to check for yaw curvature. under most circumstances, if set at the designed beam, rocker would be correct or close.}}