SS & SW Questions

A few questions:

I was looking at the spreadsheet library for something to aid hull design which ideally would create a file that could be imported into FreeSheet to access the hydrostatic utilities and other analysis. If a hull design must be accurate FreeShip's basic method produces only an approximation.

Not only was I unable to find such an aid, there is not even a category for hull design. This I found surprising. Can new categories be added?

Most if not all of the spreadsheets I did find are Excel. I use Quattro which is a linear descendant of Lotus, the spreadsheet program I first learned to use. Obviously there are more Excel users. Does anyone know if Quattro files load properly into Excel? No point in my uploading any of mine if they won't be of use to anyone.

As well as spreadsheets, is anyone creating compiled applications and if so do they have a category?

 

I honestly don't know what compatibility issues might exist between Quattro and Excel functions or what is involved in transferring any macros from Quattro Pro to Excel. I hope someone else reading this can share their experience with this.

I've created a 'hull design spreadsheets' category now that you can select when you 'Add' a file to the spreadsheets library if you would be so generous in sharing some of yours. Is the file extension .qpw?

If there is a handful of spreadsheets that would be best grouped in a more specific category, please PM me or post a category suggestion here and I will create new more specific categories as requested. Thanks very much.

 

AK

Unless you're willing to spend telephone numbers on software like this:
http://www.3ds.com/products/catia/mid-market/catia-for-yacht/overview/

You'll have to do 'it' the same way we all do...carefully and hand-draulically and build up your own library as such!

 

Thanks for the fast reply. There are some issues, apparently. I tried downloading several of the .XLS files, most load OK but a few cause errors of some kind. Perhaps it will work from .QPW to .XLS . . .

- thank you! Yes it's a .QPW file but on investigation I find that Quattro can create a .XLS file - or so it claims. I am in the early stages of the hull design SS so it will be a while but as soon as I have something useful I will post it in both flavors, in the hope that at least one will work. Perhaps someone can download it and advise if it's OK.

The "Hull design" category describes very well what I am trying to develop. The first version is aimed at generating radius chine designs with somewhat limited hull shape options.


Ad Hoc: I know what you mean about SW costs! Even before I retired from engineering my employer -who had a great deal more money than I have ever had - was too cheap to buy me a licence to for ACAD. My biggest problem now is organizing the dozens of little utilities I have developed across the years . . .

 

I'm curious about how large the errors are in FreeShip's calculations. Have you tried any test cases for which you know the exact answer?

 

Rhino does the basic volume, centroid, etc calculations for hydrostatics with the Hydrostatics and other analysis commands. My experience is the accuracy of the results is as good as or better than the relative accuracy specified for the project. The results can be copied and pasted into a simple Excel spreadsheet to calculate the quantaties of interest. Some interation is needed to maintain displacement when heeling. Rhino falls in between free and telephone number costs at around $1000 in the US. Whether that is low cost depends on the individual or organization.

Example results:

Hydrostatics
Volume Displacement = 1632.57
Center of Buoyancy = 1.465, 0, -1.22094
Wetted Surface Area = 2394.63
Waterline Length = 62.6877
Maximum Waterline Beam = 18.6171
Water Plane Area = 853.411
Center of Floatation = 1.71573, 0,0

VolumeMoments
Volume = 1632.54 (+/- 0.00036) cubic inches
Volume Centroid = 1.464683,-4.67967431e-14,-1.22097326 (+/- 4.1e-06,1.8e-06,2.1e-06)
Volume Moments:
First Moments
x: 2391.154 (+/- 0.0061)
y: -7.63975549e-11 (+/- 0.0029)
z: -1993.28769 (+/- 0.003)
Second Moments
xx: 266556.81 (+/- 0.047)
yy: 22889.267 (+/- 0.0067)
zz: 3606.767 (+/- 0.0092)
Product Moments
xy: 8e-10 (+/- 0.0098)
yz: 1e-10 (+/- 0.0047)
zx: -2623.91237 (+/- 0.016)
Volume Moments of Inertia about World Coordinate Axes
Ix: 26496.033 (+/- 0.016)
Iy: 270163.57 (+/- 0.056)
Iz: 289446.07 (+/- 0.054)

AreaMoments
Area = 853.491788 (+/- 1e-07) square inches
Area Centroid = 1.713976,9e-14,0 (+/- 1.7e-06,1.2e-06,0)
Area Moments:
First Moments
x: 1462.864 (+/- 0.0015)
y: 8e-11 (+/- 0.001)
z: 0 (+/- 0)
Second Moments
xx: 191589.469 (+/- 0.0076)
yy: 17869.9364 (+/- 0.00048)
zz: 0 (+/- 0)
Product Moments
xy: 2e-09 (+/- 0.012)
yz: 0 (+/- 0)
zx: 0 (+/- 0)
Area Moments of Inertia about World Coordinate Axes
Ix: 17869.9364 (+/- 0.00048)
Iy: 191589.469 (+/- 0.0076)
Iz: 209459.405 (+/- 0.0081)
Area Radii of Gyration about World Coordinate Axes
Rx: 4.57574517 (+/- 6.1e-08)
Ry: 14.9825641 (+/- 3e-07)
Rz: 15.6657164 (+/- 3e-07)
Area Moments of Inertia about Centroid Coordinate Axes
Ix: 17869.9364 (+/- 0.00048)
Iy: 189082.155 (+/- 0.0026)
Iz: 206952.092 (+/- 0.0031)
Area Principal Moments of Inertia about Centroid and Principal Axes
I1: 189082.155 , Direction ( -1, -1.34820842e-14 ,-0)
I2: 17869.9364 , Direction ( 1.34820842e-14, -1 ,0)
I3: 0 , Direction ( 0, 0 ,1)
Area Radii of Gyration about Centroid Coordinate Axes
Rx: 4.57574517 (+/- 6.1e-08)
Ry: 14.8842035 (+/- 1e-07)
Rz: 15.5716716 (+/- 1.2e-07)

 

Sorry David, I guess I wasn't being clear, but it's not the accuracy of FreeShip's calculations that I am questioning. Sometimes I want to create a precise shape of hull; that can only be done with certain simple hard-chine hull shapes in FreeShip. It isn't practical to get a precise shape in a reasonable time by moving the control points, and for a rounded hull more points are needed and the time seems to increase as a factorial of the points count.

 

Protoype Hull Design Spreadsheet Results

I've been working on a hull design spreadsheet. I gave up on the first attempt, way too complex. Also I had to learn about FreeShip's import file formats and experiment to establish their capabilities and limitations. Sorry it's taking so long! Finally I went back to an old spreadsheet I have used for years to predict wood bending patterns. I decided not to bother with the stuff that FreeShip handles quickly and easily. This one looks promising.

The stems generated by this spreadsheet are plumb and vertical but can be changed in a minute using FreeShip. I restricted hull shapes to constant bilge radius with a flat-bottom. Again, these limits are easy to change in FreeShip to provide elliptical bilges and vee bottom if preferred, and either hard chine or rounded bilge can be had in FreeShip.

The result of the first test is shown. It’s not ready to publish yet, as it doesn’t handle transoms and I want to add a bit more flexibility, also make it easier to use. It took about 10 minutes to do this canoe design including reshaping the stems. Also I want to experiment with the spreadsheet to see how to get the best out of it, maybe write a tutorial.

Changes to image Feb 12/13: added recurved stems and decks to simulate appearance of Walter dean's Sunnyside Cruiser canoe and firmed bilges to increase stability to allow higher seat position.

 

AK
I started with Lotus until upgrades are no longer available and hard to come by. I started using Excel and find it easy to use sans the bells and whistles of Lotus. But excel has Visual Basic programming which is great.

I am building up my Excel files on boat design but it seems there are too many categories that I have not found the time to piece everything together or possibly link it together. So far I have monohull, catamaran, at least nine different groups of displacement ships, then I have to fit in the materials in steel, aluminum, and composite.

I am following the path of design spiral and now into weight estimation WBS system. What is your goal?

 

Did you have a look at the thread http://www.boatdesign.net/forums/design-software/new-lines-prediction-program-45601.html ?
UliLines creates an input file for Delftship and FreeShip
Uli

 

- I too started with Lotus; I now use Corel’s Quattro which is it’s linear descendant. I also have an old Visual Basic set but haven’t used it since I retired. Maybe I should get Excel too: I used to use it at work.

I didn’t know Excel would do VB; does it generate a compiled program for distribution or just run it as an interpreter?

My goal with the current effort is to generate a predecessor program for FreeShip (PreShip?) to simplify creating a design and still allow access to the tools in FreeShip. I have also used Carene2008 which creates a design in a more "linear" way than FreeShip but lacks it's flexibility and analytical tools. Basically I just want to have the best of both worlds . . .

- I reviewed the manual briefly. It seems to be aimed at a professional audience with more training than I have in ship design. Many of the professional designers here would find it of interest. My own endevour starts at a much lower level which might appeal to some who wish to try their hand at hull design, or perhaps - as I do - wish to recreate several classic hulls in FreeShip for analysis using FreeShip's tools. Thank you for your interest.

 

My latest version of Excel has an add on which is activated using a procedure. I will post it. The add on contains the VB, and the usual macro and active X controls.

I look at your post again and I think you are only interested in hull design. It can be expanded to to hull optimization. My nephew wrote the VB for me in a few hours. One sheet is used as a output/scratchpad that I can save or erase if I dont like the result.

In the early days, I create waterline graphs and sectional graphs from the table of offsets in Excel. From the table of offsets, another sheet calculates the displacement using simpsons or trapezoidal rule. It calculates also the LCG. The old excel allows me to pick a point in the graph, move it using the cursor and the corresponding cell recalculate. It also has the smoothing function. I can;t use that anymore with the new version.

Another method to plot a line in Excel is to use and algebraic expresion to generate a set of points for a parabolic or polynomial curve. Or you can input manually the coordinates in the cell, create a graph, then use the trendline function of the SS to know the equation. The trendline has a polynomial function up to the 6th order. With the equation known, you can create another graph set and vary the shape by varying the inputs in the P function.

Or you can create the function using Taylor's mathematecal method. It uses a sixth order polynomial function. Each set correspond to a parameter like length, breadth, Cp, LCB,.......ect. so by varying the input parameter, the graph changes. You can create sectional area curve, waterline, sections and even profiles. The link was posted here sometime ago about "Design of Naval Ships". If you can't find it, I will fwd the link. I have saved it.

P.S.
I use to make Lotus play a tune whenever I strike an invalid key. It has a set of tone functions. Nice to remember my programming days.

 

Attached instructions for the activating VB.

Here is the link for Modern Naval Design tool. http://mnvdet.com/MNVDET.shtml

 

If I have to I will get Excel but Quattro can export ,XLS files so hopefully I will be able to put this spreadsheet into the library once completed. I have been testing the Alpha version extensively yesterday and today and the basic math is solid, so I will work on completing and civilizing it into a Beta version. It needs transoms, more control over sheers, and hopefully to eliminate a repeated calculation that is currently needed to prevent circular calculation errors, and a better user interface with graphics. I'll need to add some kind of instructions too.

 

Better stick with Quattro then. Excel is good but lacks flexibility as it works wit a set of programmed commands. They touted it as the 3G (third generation) way of computing. The old Excel is in binary format. The new one isn't. I programmed the Lotto 6/49 combinations in the .xlsx version but it won't fit so I saved it in the old version. For purely number crunching, the old system is the best.

I don't think it is the accuracy. It is the way it is used. The only inaccuracy that is in the Excel is the way it handles statistic. You can search the net for Excel's accuracy before you think of switching.

Excel is is getting sophisticated though and I have not explored other possibilities.

I started with Framework by Ashton Tate, then Lotus. I consider both a programming tool because you create.