How do I go from simple hull design/lines plan to dimensioned plans/

[gonzo]

A computer program is usually written by programmers that know little or nothing about boats. The practical knowledge of using, building and repairing boats is what leads to good design. I have nothing against computers, they have good uses. However, many would-be designers expect a computer to do the thinking and learning for them. Look at other similar boats, and if your design is way off in lines or structure ask yourself why.

[PAR]

He's an engineer now Gonzo, so he should know the ramifications. Fred has a point and with a length of line these can make interesting anchors, though your bow roller will need modification. If you can bend Sam's ear for an hour over beer and a lunch, then you'll absorb more then a few books.

[pdwiley]

Originally Posted by gonzo

A computer program is usually written by programmers that know little or nothing about boats.

Sorry but you are totally wrong.

A computer program is usually written by programmers that know little or nothing about anything outside programming.

PDW

Recursion: see recursion.

[rambat]

I will try to get back here more than every three months, imagine my dismay when I read "Part-Time" was DISCOURAGED by so called professionals here to give it up! I tell everyone that wants to build his own boat and worries about it working well the same thing "If one is watchful and does a lot of fun research riding, piloting and repairing boats he can learn what he needs to make a boat that not only works well, its truly his personal baby.
This is BOAT DESIGN.net, we enthusiast here are supposed to sharing, advising and encouraging other seeking our rewarding addiction!
Too many people of all trades get a PC program and think it will enable once hidden insightful superpowers, its just a tool.
The direct same function a PC 3/D program replaces is good scale model hull building done in the physical world, the PC model iterations get quicker and full scale geometry a little less than 1/8" resolution, but that is all. Take it from a self-taught boat designer that still creates more real world designs than most named NA's. It was many self-taught mentors here in South LA, themselves having designed more working vessels ever launched in the world (Halter/Trinity). They told me confidentially, "boat design is the last true constructive arts left unrestrained by conventions and science. Its still beyond the grasp of chaos modeling and still favors human cultural input over science in every corner of the globe" Levi cautioned me in the late 80's as I was breathlessly showing him the latest (first) PC based hull modeling/design program, he stopped me and asked, who told the program its all exactly so? some human programmer that has probably never sculpted a hull, trimmed a sail or hammered a throttle...?

[rwatson]

People who think assume programmers are just one dimensional people, with no other skills but programming, are exhibiting the most blatant form of "professional myopia", where they refuse to believe anyone else in the world can think and learn.

Every software product that boat designers use is the result of thousands of hours of designer/programmer collusion, and you can be sure that the programmer with the mental ability to assemble the software either has, or ends up with a great deal of knowledge about what designers and NA's need.

[pdwiley]

Originally Posted by rwatson

People who think assume programmers are just one dimensional people, with no other skills but programming, are exhibiting the most blatant form of "professional myopia", where they refuse to believe anyone else in the world can think and learn.

Every software product that boat designers use is the result of thousands of hours of designer/programmer collusion, and you can be sure that the programmer with the mental ability to assemble the software either has, or ends up with a great deal of knowledge about what designers and NA's need.

So...... you're a programmer, then?

I can't totally disagree but IME - which is extensive - people with degrees in IT are not very useful except as code monkeys, for years. They need a lot of supervision and very, very good design documents.

Of course the big difference is that people my age took their first degree in engineering, science, math or similar then learnt to program so as to be able to solve the problems they were interested in tackling.

Mind you some of the most abysmal, un-maintainable code I have ever seen was written by a scientist I used to work with in a CSIRO division. You could use it as an example of how to write spaghetti code in FORTRAN.

From some of what I've seen recently at another CSIRO division less has changed than one would hope....

PDW

[rwatson]

I've done my share of programming allright - and I have never met anyone who thought the someone else's code wasn't "spaghetti " - so that must mean that everyone writes "spaghetti".

My coffee cup besides me has a lot of 'digital witticisms' on it - like :
Weinbergs Law
"If builders built buildings like programmers wrote software, the first woodpecker that came along would destroy civilisation"

.. and that was written by a programmer.

But, if anyone ever describes other peoples code as spaghetti, I love to ask that person to submit their own work for peer review, and make them sit through the criticisms of all the blunders and bad layout in their work.

Programming is as hard a work as writing novels - but few novel writers have managers standing over them with bullwhips and branding irons.

[pdwiley]

Originally Posted by rwatson

But, if anyone ever describes other peoples code as spaghetti, I love to ask that person to submit their own work for peer review, and make them sit through the criticisms of all the blunders and bad layout in their work.

Shrug. Mine's been through peer review many times over the last 30 years. The code isn't perfect but it works. Last time some of mine was reviewed the argument sunk to arguing about variable names, whether it should follow K&R or ANSI C coding conventions and the like. I ignored it.

At least 3 of my systems are open source and in everyday use so anyone can critique it. I just uploaded a bunch of changes to one of them this morning.

I only program in OO languages these days. Makes it harder to write spaghetti code.

Anyway I still stand by my point that programmers don't necessarily know anything except how to turn design documents into functional code so saying that one would know naval architecture from implementing a system is a very long bow. I wrote an accounting consolidation system for a big multinational once, working with a couple of very smart accountants. That didn't make me an accountant (thank God, I can't spare any more brain cells).

PDW

[176inches]

I used free software by Carlson Design. You design the boat by moving around the chine corners (polygons) at four cross-sections, including the transom, plus the bow. Or you can enter actual coordinates if you have some design you want to replicate (only if it's not copyrighted, of course). The software fits the lines around those points. Then you can get drawings and coordinates of any number of frames by specifying the position along the centerline (Z axis), as well as all chines/strakes. Only works with angular cross-sections, though. You can see the result, a 15' lapstrake boat with 4 strakes pers side, in my blog, at http://176inches.blogspot.com. I messed around with number of strakes, V- versus flat bottom, and everything else you could imagine before settling on the one I used. A useful part is the displacement and righting moment calculator. Clunky interface and lots of limitations, but hey, it's free.

[Petros]

Shawnzoom,

Designing an optimized structure of the hull is a complex engineering exercise. Unless you want to learn another career, you can just copy the structural details of a successful design that is about the same size (and speed/capacity) as your design will get you something is pretty good.

For most of boat building history design details evolved slowing over time by just copying what worked. No reason that will not get you something pretty decent today either.

This is what I would suggest; Buy a set of plans for a modern design, using the contruction method you want to try, about the same size and capacity of your design, and than just adapt the hull shape to the details of the plans you purchased. If you are going too far outside the envalope of plans, make it a little stronger (not too much, you will add weight fast if you do).

Good luck, have fun, and do not stop at the first one. Doing is the best way to learn.

[viking north]

My first builds were constructed from scaled models, 24 to 36 in. in length based on local fishing craft. These having evolved over a couple of hundred years of trial and error. While I always had a good grasp of math and drafting, I never could warm up to computers and this has and will limit my using this amazing tool.If I had to do it over again I would have warmed to computers and taken a good basic boat design home study course and applied such to refining my models and builds. While I am an experienced builder I will never achieve the gratification and knowledge of designing. Having said that,I feel, hands on regardless of the outcome, prior to engineering study does give one the edge. Thus the often recommended response of "purchase plans and build" should not always be taken as a discouragement factor, more so the best possible advise in setting you on the right track. I highly recommend it prior to "warming up to that bastard computer" ---Geo.