29082011(Lofting)

We started lofting this morning. I read about it on the Gougeon brothers on boat construction last weekend, but it was really hard to understand, so I was looking forward to the class today. We talked about the Autocad drawing dinghy09 for how long we need the cardboard individually. I made a pair with Tapu.

running measurement - when measuring and ticking quite a long length we can use this method with using a tape measure

trammel - similar to compass

sheer line - on the profile

deck line - on the half breadth

ghost line - for makeing sure the thickness is exist on the base line of the bottom(is it different from keel line?)

loft floor

chine - like a joint or connecting line to make the boat stronger and easy to handle

canoe body - the base line of the boat

square batten

profile - represents the shape of buttocks

half breadth - waterlines

body plan - stations

What we firstly did is we drew a centre line on the far bottom of our cardboard. This line can be thought as a base line or starting point(line). Our cardboard color was pink which is not bad but slightly narrower than the others. Next, we drew F.P(Forward Perpendicular line) and A.P(After Perpendicular line) at the right angle of the centre line we drew. We need to drew these lines as accurate as possible, otherwise it will bring annoying and concerning as time goes by. What impressed me about making those lines perpendicularly was that we do not need a rule or a tape measure. Richard showed us how to draw reasonably accurate lines of those. Then, we used a steel rule and a straightedge, we drew the rest of the grid. We can drew the profile grid from the WL4 which is the maximum or highest water line(is that right?) and can drew the half breadth grid from the CL which is the center line of the longitudinal cutting surface. Basically, each lines of plan has horizontal and vertical straight lines and one bunch of curved lines as we can see on the table of offsets. Each table has two sets of points and those sets make curved lines. The table of offsets we saw today was a bit different from the book. We tick the points to draw curved lines from table of offsets. My knees~but the loft floor looked lovely for me. Richard said that sheer line, keel line, chine, deck line and additionally ghost line are the main lines when lofting. We do not have to worry about the body plan. It will be coming up automatically from those two plans(profile and half breadth). There were not enough proper length of battens, so Tapu and I ticked all the points and looked at the other mates doing. If there are not much shape on lines, it will be better off laying a batten down on wider surface. The more tension it has, the nicer shape of line can be made.

On the way home, two questions poped up my head.

What if there are no sources like table of offsets or previous ship data and even a certain design program, how can we create something from nothing? I think the first thing to do lofting is making table of offsets, but how? The second one is that what kind of wood will be proper to use as a batten?

I found the table of offset file in Unitec student driver on the website(Lance showed me).