Help with calculations using Simpson's rule

Doug,
Yours were the first email I sent/replied to and it shows sent in the outbox.

Nevertheless, I resend it and also sent the same (backup) as well from my private email address just in case. On both emails will be four spreadsheet attachments: 10 station and 20 station displacement calculations sheets with Cp, LCB, VCB, Cwp, Immersion and moment to trim.
Then another two: 10 and 20 station WPA calculations with CF.

Please let me know if you received it OK this time around.

Best regards

 

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Wynand, thanks! I've been gone most of the afternoon and it was here when I got back. I appreciate your effort.

 

I say toss Simpson's Rules altogether and use Tchebycheff's rules.

But then, I'm lazy.... :grin:

 

This is a very generous offer by you. Similar to your experience I first worked out a spreadsheet back in the 1980s. It was on Lotus123 at the time, since Excel was not the spreadsheet of choice for the PC in those days. Later, after Microsoft adopted Excel I transferred my sheet from Lotus to Excel.

I do wonder why anyone who is interested in boat design hasn't already done this for themselves. It should be a natural part of the learning experience and seems like one of the first things you would consider. There are other spreadsheets that anyone interested in design should also have done on their own, for example a rig calculation sheet for those interested in sailing craft.

Hopefully those who have asked you for a copy are simply using it to compare to their own version.

 

Actually Paul B, I wrote the original spreadsheets on Lotus 123 (still have them) and later converted them to Excel when MS took over Pc's.

Today you can timber a design together in a few minutes using design software and have hydrostatics on the fly. Change a line and immediately see the results.
However, in 1989 when I started with my Small Boat Design Diploma course (Well known English Institution) software was rare and basically non existent In SA with the exemption of very early Vacanti Software that cost a fortune. All drafting was done on paper and the planimeter an essential part of tools. It was relative easy to changes some lines, run the planimeter over to get areas, but the number crunching took most time and prone to mistakes.
As a lazy bum. necessity is the mother of all invention and I done very basic and effective spreadsheets on then Lotus - to simplify calculations - with a very elementary knowledge of it - only got my first computer that year and everything new to me. Save me a lot of time altering a design and calculations to follow...

But these basic sheets were so useful and effective originally that until now I never bother to update my use of formulas on them and still used it until 2 years ago when I did my last design, yes, on my trusted drawing board.

If you have not done boat designs on board and paper, calculated all the hydrostatics, mast and rigging etc by hand and calculator, you have not mastered the art of boat design.
Much to many "computer" boat designers out there that does not even know how to calculate the basics of basics - all done by the click of a mouse....and those do not need to bore me with the pro's of doing it on CAD and related software. These things must be considered a tool in your ability and not a necessity.

Lastly, I have bought some decent software programs over the years like Vacanti, Maxsurf, and others but never liked them and preferred the old ways - board, paper and pencil that have soul and like good wine - the longer it takes, the better it is... Nothing better than to ponder over some beautiful hand drawn lines on the board with a hot brew in the hand.

 

I don't have my originals anymore. They were on 5.25" floppy discs and I have not had a computer with one of those drives for a long time.

Of course the first iteration of the sheets for Excel were on 3.5" discs and I don't have a machine that runs those anymore either.

This is where the Lotus/Excel sheets were most useful. They are basically the same as doing the calculations with a pocket calculator, but you only input the formula once. Therefore the possibility of a mis-key mistake is removed.

I have no issues with computers to do lines or calculations. However, if you are going to do this work I agree you should know the basics of how the numbers are crunched.

 

..you can check out Duran's Rule and Weddle's Rule in addition to the Trapezoidal and Simpson's rule...
when mess'n around, I sometimes apply all four to the same problem just to see what turns up....

..from your question as to crunching the numbers..sounds like you haven't gone far enough. Without knowing what you started with and where you arrived I cannot offer a solution....but you need one more step to cube that square footage....

I am not a pro so I really don't have need of CAD nor any design softwear with my design efforts..I do agree with Wynand N that there is a lot to be said for the drafting board and pencils, etc....it just feels RIGHT....

 

I'll vouch for the drawing side of things. My degree is in Industrial Design, while I'm not much for the drafting board, Ido draw everything before I ever open Rhino or Solidworks. Nothing like a stack of 11x17's, a good bic pen, a pile of prismacolor markers, and some good music...