Least Square Method (linear) - Freeboards and drafts

[Transom6.3]

Hi Guys,

I have seen the least square method (linear) in a number of inclining test reports when used to get the inclined waterline from a number of freeboards measurements and drafts.

I have no idea what the formula/process is, does anybody know?

I realise there will never be a perfect straight line through all the freeboard measurements so this method must average the differences out.

Thanks for help.

[Ad Hoc]

have you looked at the ISO code?

[Raggi_Thor]

It's a lot of work to do this math manually.
Say you have measured some heights (y1, y2, y3 etc) at some given locations (x1, x2, x3 etc), then find a straight line Y = ax + b (calculate the constants a and b) so that the sum of the squared differences between all your measurments and the calculated Y is minimized.
Excel or OpenOffice does it for you.

[Transom6.3]

Thanks guys,
I'll look into it and try and set up an excel spreadsheet.
Does anybody have an excel template.

[Raggi_Thor]

http://office.microsoft.com/assistance/hfws.aspx?AssetID=HP052091551033&CTT=3&Origin=HP052091081033&Client=1&app=OF&ver=11

[Raggi_Thor]

I think the easiest way to do it is to make a chart, see:
http://www.chem.purdue.edu/gchelp/tools/graphing.html

[Transom6.3]

Thanks alot Raggi,
That's a big help.