The lofting floor is all laid out now. The grid is drawn as precisely as possible by stretching builder's twine just above the lofting and squaring down to the floor.
Along the base edge of the lofting floor we screw down a raised, straight strip of wood. This strip lies exactly along the baseline of the lofting, and the long line measurements given in the table of offsets are referenced from this line. The table of offsets is a set of measurements from the designer that the loftsman uses to draw the boat full size on the lofting floor.
To make sure that the baseline is exactly straight and at the right distance from the grid we've drawn, we use a scrap of wood marked at exactly 12" (the distance the designer designated from the grid line to the base line). With the baseline strip butted up against the wood scrap, we move the strip until the grid line intersects the mark on the wood scrap, and then screw the base strip down to the loft floor. Now when we need to take measurements from the lofting, we'll always butt the tape measure (or tick stick... more on that later) up against this baseline so that we're always reading from the same place.
Tomorrow we'll start drawing the boat, beginning with the profile and sheer, and then moving on to the body plan.
Just for reference, here's a lofting of a boat designed by Dudley Dix
(image used by permission)
The lofting shows 3 different views of the boat, sliced in 3 different ways.
- The upper drawing is the Profile View, and it shows the boat from the side. The horizontal lines are called Water Lines, and they slice through the boat horizontally. The vertical lines are called Station Lines, and they slice the boat top to bottom, and side to side. The curved lines in this view are called Buttock Lines, and they show slices of the boat made top to bottom and front to back (as if the boat sailed through a series of vertical knives...!)
- The drawing on the right side is called the Body Plan. This view shows the boat from the front. The boat in this view is sliced like a loaf of bread, these slices made by the Station Lines. You can also see the horizontal, Water Lines in this view, as well as the vertical Buttock Lines.
- The lower drawing shows the Plan View (the upper half) and Diagonals (the lower half). The Plan View shows the boat from the top. The slices in this view are made by the Water Lines. The vertical lines are the Station Lines, and the horizontal lines are the Buttock Lines. The Diagonals are a little stranger. These are slices through the boat made by the diagonal lines that you see in the Body Plan.
All of these views, taken together, give enough information for us to precisely build most parts the boat.