Re: QT skiff - no instructions or short instructions
Yes, along the curve of the sheer and add two feet or so, which will make bending them on easier. Longer provides more leverage, and the portion overhanging the end of the boat can be handy to have as leverage. You then cut them off flush with the boat.
Nothing on length so I measure the length?
As you've discovered, plans are not instructions. Most plans are produced so that the basics are there, and rely on the experience and resourcefulness of the builder. Coming here, you are being resourceful. Building this boat, you are gaining experience.
There are two kinds of boaters: those who have run aground, and those who lie about it.