Monday, December 12, 2011

Measuring errors!

Not a lot of time today, I have been invited to a Christmas party. So after tidying up the garage a little I started to mark up the bottom. The scarf I did yesterday was not the best in history but I think it will be ok, after all the bottom will be covered in epoxy and glass fiber.

Scarf joint

I started to mark the centre line and the idea was to do the grid for the curve of the bottom and the frame positions, to separate them I will do the frame positions with a fine sharpie marker and the rest with pencil. The grid for the shape of the bottom is at 200 mm spacing so the first step is to mark of the centre line every 200 mm, then you need draw a line square to the centre line at each of these marks. To make sure I get this correct I took a piece of plywood with a straight edge, at 90 degrees to this edge I drew a line across the plywood. I placed the piece of plywood on top of the bottom ply and aligned the centre line with the line on the plywood piece at each mark and could then draw the line across. Maybe a picture will make it clearer?

Template for drawing square lines (the lines do not look aligned, but that is only the angle of the camera)

Unfortunately I did not double check my initial marks before drawing the lines, and when I was marking out the frame positions something seemed strange. A quick check with the tape measure showed I had been sort of half a millimeter wrong in most of the markings, so that the boat became 12 mm longer than designed.

Aaahrrrg, this can not be right!!! It is supposed to be 4408mm!!

That was all I needed to call it a day. Will bring out the eraser tomorrow, or just leave it as it is?