Making a model from a table of offsets?

[fyffe555]

Hi all, new owner of V3 and still getting to grips with it.

I'm trying to model a boat hull with the shape defined in a table of offsets. The Table is in the form of stations along the centreline and breadths and widths at each station such as ;
http://home.att.net/~ShipmodelFAQ/smf-q078a.gif

Dimensions are of the form 4-6-2 meaning feet, inches, eight's, which for rhino input I've converted to inch decimal with a spread sheet.

Here's the problem. I can draw the many hull shapes (yup, pen, paper, drafting machine, spline, eraser, eraser, eraser,,,, well you get the idea) using inputs from the table and get pretty fair and accurate output.

Trying to put it into rhino I'm having problems working out how best to achieve the points required and then produce the mesh and render accordingly. I'm getting a very unfair (bumpy) surface even on simple shapes.

Is there a simple method of entering these points that I'm missing? Direct from a spreadsheet perhaps?

Once I've got the points defined how best to produce the shape they define?


thanks

Andrew

[High Seas]

Andrew -
I've been exploring the same path - though it sounds like you're further down the track than I am . ( I got stuck reflooring the Masterbedroom- so I've had to belay my modeling exercise)

Check out this site - I'm using it as my tut to work a hull:
http://www.3drender.com/rhino/Boat/
check out the sailboat modeling tutorial - its a long process. I;d think having the table of offsets could make it a bit easier than tracing the section lines and waterlines as in the tutorial -well, maybe? Let me know how it goes - BTW - What type of hull you doing? D-ooh just looked - its a sharpie -- cool!
Cheers - Jim

[duluthboat]

Andrew,

This question has been asked many times on other forums, but I think it’s the first time here. I like Rhino because it is one of the few reasonably priced surface modelers that will model a hull with accuracy. The accuracy can be an obstacle when drawing a hull from offsets. In most cases the offsets where created on the drawing board and intended to be lofted full-size, where any mistakes could be adjusted for. In Rhino, the points are entered for each section, you must fair that section. It may take a little fussing, fair, then adjust, back and forth until the section fair and very close to the points. It can be tedious, much harder than then drawing a hull from scratch. There are also some tricks to get the stem from getting funny. If your object is to create a 3D model to be used in CNC then keep at it, if you just want to build the boat, loft it, it’s much easier.

Rhino has some tutorials for drawing hulls plus I would recommend you check out the software section at this forum . Do a search for Rhino there, you’ll find lots of stuff.

Gary

[fyffe555]

Thanks for the replies and Links,

I've lofted boats before and even built a couple from the scribbles on those white painted 8x4's on the floor. kinda fun but tough on the knees sometimes. One (21' day sailor) is still floating.

I've drawn a few for entertainment too. I did produce a couple of Rhino STL's a while ago on an early demo version of rhino that came out ok, simple stuff but fair and good enough to run through meshcam and mill a few nice looking, if inaccurate half hulls. Problem is I can't remember how I did it, old age setting in.

Now with a shiny new version 3 and flamingo etc I can't get the thing to work out right, more precisely I want to fair true to the offsets and not happy with the good looking if slightly bumpy product i have now because it's not fair to the original. The original table does fair out fine on paper and the table (with a few corrections) have been taken from existing boats (Herreshof, Chapelle). Want an accurate model for no other reason than thats what I want to do and until I get it there I'm not going to splash the cash for the Cam component ( probably visualmill) that will do contour or waterline machining.

I have found that I've probably got too many points on the thing. Some of the Herreshof stuff have a couple of hundred entries for stations, diagonals etc. Removing a lot of points, especially around the stem and complex curved sterns actually makes the thing fair better, just not accurately.

I'll keep at it and if I find a solution I'll write it up here.

Andrew