dont worry too much, its possible that i am wrong, i dont think so be cause my boat seems fine. its not like distance would change, but i made the mistake of measuring from the wrong side at the middle. it took me like 4 times to get it right. ther are several eraser marks on my stong back too.

i would re-measure the strong back mark the placemets and if it is too short, just but a spacer on the stern end form to stick it out an inch. its no big deal.

the sheers will make sence when you go to actually place them on the forms.