Hullform SW vs Pencil and Paper

[Shalfleet]

I took Paul Jeffrey's advice and downloaded the shareware Hullform software from Perth Aus. I entered the offsets from a couple of professional designs I like as a sort of study method and started to transfer offsets from my paper design into the program to compare the key hydrowatsit numbers. What I quickly discovered is that the process of doing it on paper is a little redundant and the program can be used to create quite lovely fair hulls of the shape I like after a little practice. They can even be viewed in 3D using a seperate GLView program and all this without spending a penny/dime.

Being a lover of manual woodworking tools I feel a little guilty but I think I might dump the ships curves I bought for $15 the other day!

One thing I'll try to do is print out fullsize sections on a big plotter which will avoid the lofting process......does anyone know how to do this?

[ 05-06-2002, 11:00 PM: Message edited by: Shalfleet ]

[Paul Jeffrey]

First you will have to contact someone who has a plotter/cutter and see what type of files they need to be able to run their plotter. I think, now I am in trouble again thinking is dangerous, that standard .dxf files can be easily plotted out. I can't remember if the hullforms exports dxf files. But I think that files for GL are also plotable. Again it will depend on the people who have the plotter to tell you what files they can plot out. A lotta help I am ;)

Paul J

[Aramas]

I happen to think that Hullform is seriously horrible (I use AutoYacht). The best freeware hull design program I've seen is Carlson's 'Hulls' although it's application is limited to multichine ply and ply lapstrake.
Download 'Hulls' (http://www.carlsondesign.com/hulls.zip)

[fair&fair]

To get patterns milled or printed, then you should be able to save your design as a DXF file. I use a 3d surface modelling program (multisurf) in addition to a 2d program (autocad and microstation) to alter files and prepare them if I'm sending them off to be cut. As far as plotting goes, there are plenty of people around with that capability. You can pick up a cheap plotter for $200 or less if you look hard enough. I know ebay has good deals all the time.

[Aramas]

With regard to plotting, you can have it plotted onto/cut out of mylar (paper distorts with humidity), and most sailmakers can do that. Perhaps a more direct approach is to find a woodworking shop that has a CNC router, and have the moulds cut out directly from the CAD file.
The standard CAD file format is .dxf, and anyone with CNC equipment will probably have the software to convert from that. Find someone near where you live and give them a call.

[John Bell]

I'm another fan of Greg Carlson's "Hulls" freeware. Even though I've got two friends with CNC routers, I still just dimension the expanded panels inside a CAD program.

I've designed a couple of boats this way, including some that have actually been built by third parties. And so far, knock on wood, everything has gone together without a hitch.

My current design project is a 17' vee bottom garvey that I plan to build as my next boat. And yes, it was designed with Hulls.

JB

[carlg]

Here's another vote for "Hulls." It's simple, accurate and, best of all, free. I use it in conjunction with QuickCAD, a $70 subset of Autocad. Just finished a 20' electric double-ender and everything went together as calculated.

[John Bell]

A design forged on Hulls and the free version of TurboCad 2D:

http://jmbell.home.mindspring.com/blackberry/blackberry-small.jpg

(I did not build it, but that is me in the picture.)

[David Payne]

I use Hullform 8, butI still like to draw plans, so I use it to rough out lines, once I've done a pencil sketch proposal. Then I use it for all the hydrostatic, stability etc calculations.The 3d perspective is handy as an underlay to draw up a nice perspective by hand.
This all might seem a little crazy to some of you, but I was brought up in the steam age so to speak and I do like the art of drawing things by hand, so I'd like to think I have found a good balance of modern and old ways. Send me the ships curves, don't dump them in the tip.
The Carlson Hulls freebee looks quite good, is it easy to get a set of expanded plate/strake offsets from the design once you have got the plan together?

David Payne.

[ 06-04-2002, 09:22 PM: Message edited by: David Payne ]

[Dave R]

David, you can get a set of offsets, a table of points to plot on plywood and drawings of the panels from Hulls. The various drawings; 3-view, bulkheads, forms, and hull panels can be laid out on "plywood" so you can figure out how many sheets you'll need. The drawings can be exported as DXF format drawings.

I put the DXF drawings in a CAD program and scale it to make paper models. The models I've done look just like the 3-D drawing on screen and it's certainly nice to have the model in my hand.

[John Bell]

It's fairly easy to get the layouts for your expanded panels from Hulls, but learning to do it well takes a bit of practice.

Gregg has included a module that allows you to see how you might nest the panels on plywood. It will output information to plot the expansions, but IMO it is not enough detail to do it acurately. The nesting module is a good tool to quickly figure out how to get things to fit, though.

The program also outputs DXFs of the expanded panels, bulkheads, frames, decks, and transoms. What I do is import them into a CAD program to lay out the nesting and measurements.

I start with a CAD drawing of as many sheets as needed of 4x8 plywood divided into eight 1'x4' sections. The panels are arranged on top of the plywood. Using the orthagonal dimension tool in the CAD program, the dimesions are picked off where the panel intersects the grid on the plywood. Using the "snap to intersection" funtion makes this easier. After all the dimensions are measured, the grid lines are removed or hidden to make the drawing easier to read.

I've got a couple of examples of the resulting drawings availible on my website. (Click on the website icon above.)

It's a little involved, but with practice you can get the layouts for a small boat out in not much over an hour and a half of work. I think it's fun, but then again I'm a little strange about these things.

JB

[Don Z.]

Gee... it really is a shame you spent all that money on something that's obsolete. I'll tell you what... to minimize the loss, I'll send you $10 for the complete set...