03092011(Logting-modification and calculations preparation)

Our goal on wednesday was to finish the lofting, but we could not. The more the lines come up, the more complicated modification it needed, which means it was getting more accurate. Modifying the lines is not really difficult, but we have to take our time and be patient. I think the key point is 'check', one line by one another line on another view. Our boat is a dinghy having a chine, so we have to draw waterlines and buttocks in a way of three steps, which intersects the chine. I thought that probably we could do that into two steps because two lines of topside is in one surface and the line under the bottom is in another surface, but I was not sure and still I am. We have not finished anyway, that is all right though.

Here is the sequence.

Buttock bottom

Buttock topside

(draw lines from the bottom first to the topside next)

dish them all - Chris's expression

What a cute picture~

our working these days

the pink one just below is Tapu's and mine

tasks next week

I was looking into CAT Theory CD and it has heaps of information about boat building. I saw Andrew's result on google last night, so I tried as well. Forward has more detail than aft, which is the reason that there are extra lines on the forward, so I put extra factors on equation.

Have a look~

1st factor on the third 1-4-1: 580/770

2nd factor on the fourth 1-4-1: 380/770(not exactly 1/2)

 

AP

stn.7

stn.6

stn.5

stn.4

stn.3

stn.2

stn.2

FP

Ord.    0.448

0.498

0.53

0.535

0.505

0.406

0.309

0.176

0

1st            1	4	1
2nd		1	4	1
3rd				0.75324675	3.01298701	0.753246753
4th						0.493506494	1.97402597	0.49350649

+ 

Sx.            1

4

2

4

1.75324675

3.01298701

1.246753247

1.97402597

0.49350649

Func.  0.448

1.992

1.06

2.14

0.88538961

1.22327273

0.385246753

0.34742857

0

so that is not exactly 1 4 2 4 2 4 2 4 1

common interval: 0.385m

therefore 1/3 c.i.: 0.1283m

sum of func.:        8.4813m

therefore area:      1.0884m2

and I thought the total is:         2.117m2(because the area above is from the half breadth)

Here below is the centre of area.

	arm	function	moment
A	4	0.448	1.792
	3	1.992	5.976
	2	1.06	2.12
	1	2.14	2.14
stn.4	0	5.64	12.028
	1	1.22327273	1.22327273
	1.50649351	0.38524675	0.58037173
	2	0.34742857	0.69485714
	2.49350649	0	0
F		1.95594805	2.4985016

moments from AP to station 3 incl.= 12.028

moments from FP to station 5 incl. = 2.4985

12.028-2.4985 = 9.5295(positive direction to AP)

sum of functions = 8.4813

common interval = 0.385

therefore 9.5295 / 8.4813 * 0.385 = 0.433 from stn.4 to AP

that number definetely has to have a certain measure which is 'm', but I can not figure it out so far.