One of the most critical steps in building a boat is to develop a fair sheer line and trim the hull to that line. The sheer line is the line where the hull joins the deck. It’s probably the most scrutinized line on the boat. It’s what everyone notices.
It’s given to you in the plans, and if you did a good job of lofting, the ends of the frames do a nice job of defining the sheer for you. The only trouble is, the frames are on the inside of the hull, and you need to see the line on the outside of the hull to gauge it’s fairness. That’s where a “jump stick” comes in handy. It’s just a board with a straight edge and a notch that lets you transfer that line. This is a case where a picture is worth a thousand words.
Take the jump stick and transfer a tick mark at the top of each frame head to the outside of the hull. Then connect the tick marks with a long batten. Of course the lines from each side meet at the bow, and the corners where they intersect the transom should be level.
Once you get the line, take a good look from as many angles as you can. A sweeping look from the bow and stern is a good strategy. Let your eye scan the boat lengthwise as you roll your head away from the stem to take in the curve of the bow. I take my time with this. You may have to fudge the batten up or down a bit here or there. You don’t want any bumps or hollows along the line. It should be “eye-sweet and sea-kindly”. You’ll know it when you’ve got it.
A jig saw is a good tool for making the rough cut. Leave a good margin. You can follow up with a power plane to get you within a quarter inch or so. Complete the cut with a sharp bench plane to produce a rolling bevel that will follow the curve of the deck beams where they join at the clamp.
great advice in general … “eye sweet and sea kindly”…talk about a fair sheer line!
Yeah. I love that phrase. I use it as often as I can!