Stuck In The Past Or Not Sold Yet?

The subject of hull design programs comes up fairly frequently in discussions about boat design. Although I have tried the demos and read reviews on most of these programs, I have yet to plunk down my own hard-earned money on any of them. No matter which one I try, there always seems to be something with which I am just not comfortable. Usually this involves the lack of commonality to my long practiced manual methods of designing a hull.

When I start a new hull design, I work the old fashioned way. With my battens, ducks and pencils, I work out a shape that I like and then calculate a simple set of hydrostatics using my planimeter. I used to calculate the hydrostatics by hand with a calculator, but I now use my computer and a version of the old hydrostatics form I have programmed into a spreadsheet. If the preliminary numbers look good, I'll add a little more detail to the lines and then start taking the offsets from the preliminary drawing.

This is one of the worst parts of the project as my eyes are now so bad that I have to squint and lean over until my nose is just above the drawing board! This, of course aggravates the bad discs in my lower back and it takes a day or two before I can stand up straight again. I have bi-focals, but the lower part is so powerful that it restricts my vision to a narrow band at a very set distance. I have since found it easier to just take the glasses off. These offsets are then used as points which I enter into my CAD program, Ashlar-Vellum® Graphite. This is also done without glasses as I can never figure out which part of the lenses I should look through!

From this point on, the hull is designed in the CAD program. I use the spline tool to draw lines through all of the points. I then fair the hull the same as I would by hand, making sure all of the views agree and all of the crossings line up properly. When it looks good on screen, I plot it out and put it on the desk for the true test. At this point, I stand at the drawing board and sight down the lines at all sorts of angles and from all sorts of directions. It probably looks pretty comical to those who aren't boat designers (especially as I am taking my glasses on and off to make sure it looks good both fuzzy and mostly not fuzzy). If everything looks good, I use the CAD program to measure the section areas and centers and put these numbers into my spreadsheet to get a final set of hydrostatics. The CAD program is then used to pull the corrected offsets for the actual finished set of hull lines.

I am sure those of you who are designers are shaking your heads and laughing at me by now, terms like "idiot" rolling off your tongues. But there is a reason for all this pain and suffering. I can not find a program that lets me design a boat the way I was taught to do it at The Landing School. The same time honored methods that have worked for decades. I can't see how fair the lines are on the screen, even though I have a 19" monitor set to 1600 x 1200 resolution. I know, I am supposed to use the little curvature exaggeration things to fair the lines. It just isn't the same.

Then there is the problem with nomenclature. I don't want to draw on a grid of columns and rows. I want waterlines, buttocks and stations! If I designed many round bilged boats, I'd want diagonals as well. I want to easily create the same shape as a #50 ships curve. I don't want to use the curves that the mathematical calculation says are fair, I want to use the non-mathematical ones my battens and ducks produce. I also want an even number of stations, preferably ten, spaced along the waterline. I can't stand looking at a set of lines and not being able to tell where station #3 is without some type of scale or mathematical manipulation in my head.

The use of these hull design programs has led to another minor annoyance. I see more and more lines drawings these days that have no dimensions or station marks or even title blocks. With the advent of using CNC machines to cut plugs, there is now little need for a traditional lines drawing. While the hull can still be built, there does seem to be something lost, like the ability to look at a lines plan and see the location of the design waterline.

As I know nothing about how these hull design programs are written, I can't say what could be done to make them act more like designers work on a drawing board. I guess most designers accept these limitations and adapt their work habits accordingly. I just have not been able to bring myself to adapt just yet. Whether this is due to my being stuck in the past or just not sold on the benefits of hull design programs, I can't really say. I just hope someone comes up with a program I am comfortable with before my back and eyes give out!

Timm Smith
January 26, 2004