# Seeking to Learn

Discussion in 'Hydrodynamics and Aerodynamics' started by SlickMick, Apr 3, 2021.

1. Joined: Mar 2021
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### SlickMickNew Member

I've been a sailor for a decade and over that time I became a maker. My building skills have gotten to the point where they are meeting my love of sailing. I've gotten so excited about starting to learn how to build boats (a 10 year plan for sure) that I can't sleep at night sometimes.

I'm hoping somebody can point me down a path of learning instead of me googling bits and pieces. Things I need to start getting a grip on:
- Calculating sail design: How much sail area do I need for a vessel x size and a lift coefficient of 2? How much force is on those sails? How much force and where is on the mast? Which leads me to the next section.
- Using fluid dynamics simulators: What skills do I need to build in order to start using this tech? CAD? Which programs? Lets pretend its a few college courses, what are they in order?

Just to be clear about my goals, right now they are:
- To have fun with designing
- To have math to backup the concepts I'm kicking around and be able to translate that to materials requirements

If you learn'd folks could point me in the right direction, I would be very grateful.

Additionally, it would be nice to have a mentor. Not somebody to do this for me. Somebody to check my math after I gain an understanding or to ask a question not answered by google every once in awhile.

2. Joined: Jan 2006
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Location: Lakeland Fl USA

I will argue that a beginning designer ought to ignore the computer until later in the learning curve. Draw on paper, using splines, draftsmans triangles and pencils. Make the drawings carefully scaled. This is where the math comes in. You can measure the sections with an architects scale and have at the basic math that will be involved. That is a beginning that will soon give you enough of an idea about design characteristics to allow you to utilize the cad program or the hydrostatics programs with a much better feel for what is going on and why.

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### TANSLSenior Member

@messabout, basically I agree with what you want to express but, honestly, I don't think that drawing with a pencil can be learned more than drawing with a computer.

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### DejaySenior Newbie

Dave Gerr calls it "boat noodling". You might have a severe case His book "Nature of Boats" helped me understand a little bit more since I have almost zero experience. Which doesn't keep me from drawing boats. I use fusion 360 which is not really good for this. There is also PolyCAD andDelftship free.

My guess is that proper CFD and composite FEA structural analysis is outsourced because it's so complex in itself and the software is expensive.

5. Joined: Sep 2011
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### TANSLSenior Member

But I believe that in a very high percentage of the small boats (length less than 24 m) that are designed today, CFD and FEA are not necessary, or better, their use in them is not justified because the advantages they could bring do not justify their costs.
It is very fashionable to talk about these topics but they serve more as a marketing tool than as an optimization tool.
Just an opinion.

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### mudsailorJunior Member

Just a little confused.....you state that you want to build something, but then talk about designing......two very different things. I would start with with building from a known designer, then expanding into design.

7. Joined: Sep 2011
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### TANSLSenior Member

@hoytedow, I still make my designs based on 2D drawings that, then, for various calculations, I transform into 3D models. I always start with a 2D GA plan and when I make 3D models, they are never the beautiful renderings that we are used to seeing today, they are as simple as possible but enough to perform some calculations that with them are more accurate than 2D drawings. When I need a beautiful 3D rendering (which almost never happens to me) I order it from a collaborator who only knows how to render.
That said, I still don't know why using a pencil helps you learn faster or faster than using a drawing program. And I say drawing program, not a CAD / CAM software.
By the way, I have never ridden a tricycle in my life, but I know how to drive cars.

8. Joined: Sep 2011
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### TANSLSenior Member

I have always liked two wheels better. The tricycle was for overly cautious children.
What about a pencil sharpener? Today they are not found everywhere. Of course, you can always draw with a stone on the floor, wall or ceiling, as our ancestors did. But they, as soon as their brains were developed, used other methods, although it took them a long time. Nowadays, fortunately, drawing can be done with tools so cheap that any child has them at their disposal. Although they are not cheap, children prefer them to a pencil.
Let's not divert the meaning of this thread any more, okay? I give you the last word.

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