Understanding hydrodynamics 101?

[JMayes]

I am new to this, and want to design my own RC model sail boats. I hear alot about boat length and hull shape at heel affecting both speed and performance. I am like Sgt. Sholtz when it comes to this, "I Know nothing." Can anyone explain it to me simply?

[PAR]

The simple answer is no it can't be explained simply. I'd recommend you try hanging out at some RC model sailing forums for some clues and of course some light reading on the basics.

What works for full size boats generally works for the models, but the ratios are quite different, because of the scale you're working in. Ted Brewer's book:

is a place to start.
Also look here (> http://www.tedbrewer.com/yachtdesign.html <)

[messabout]

You have said that you know little or nothing about boat design. Do not presume to "design" a boat in the absence of education and information. Boat design is a decidedly complex subject as you will see by exploring this web site.

If you wish to do RC sailboats you are in luck and you will not need to design your own. Many of the established classes have free plan sets. Google US One meter (USOM), International one meter (IOM), 36/600, Marblehead, Footy, etc.... Go to the AMYA (American model yacht assoc.)web site and look around.

Model yachting is great fun and you will get lots of encouragement from model sailors. Do yourself a big favor and try an established class boat first. You will find them in all sorts of sizes, from 12 inches long to more than 6 feet long.

[Jimboat]

Agree with PAR that there are a few good general books on boat design that might help you...

Understanding Boat Design

Essentials of Efficient Sail Boat Designl

...also agree with Doug Lord that Radio Controlled Racing Sailboats is excellent! [edited later]

[Doug Lord]

Originally Posted by JMayes

I am new to this, and want to design my own RC model sail boats. I hear alot about boat length and hull shape at heel affecting both speed and performance. I am like Sgt. Sholtz when it comes to this, "I Know nothing." Can anyone explain it to me simply?

================
The best book on the market is called: "Radio Controlled Racing Sailboats" by Chris Jackson-it is the most up to date and detailed book I know of.
Available thru Traplet Publications: www.traplet.com
or thru Graham Bantock's excellent "Sails etc" : www.sailsetc.com
You should also check out http://www.theamya.org/ , the American Model Yachting website. You might find a fleet near you and you could go down and check it out first hand.
Good Luck and Have Fun!

click on image:

America One and the S50-the only production RC spinnaker boats-now out of production.

[tunnels]

Once get immursed in the sailing thing do the excise of superimposing shapes over the top of each other!!, then compaire your new found understanding of what works, when ,and in what kind of conditions .
Power boats the same !!,compare what is good and what is not good , understand what works and why .
Boats may look the simular or even the same but can be quite differant in the way they perform.
Just when you think you got it all in your head look again , change direction and look for the trick stuff that is individual ,just small things that sailors do to get the edge over others .
Learn to sail and get dunked a few times in a small 2 person sail boat is a way to really get with the learning program and understand what happens if you dont pay attention .

[Chickadee]

There are some main differences in hydrodynamics between RC boats and real sailboats. Most of the time, modern planning shapes and wide hulls that add power at low heeling angles in full size sailboats are not performing too well: RC sized hulls perform better whit more cylindric sections, like older designs.

Then you can forget all those nice NACA profiles! Keel and rudder foils should be as thin as possible, and their lateral surface proportionally bigger.

So if you want to design, build, and perform in races, you need to concentrate on sails! To have the fastest boat, use some good free hull design, add some slight modifications if you like, and learn skills to design and build the best sails you can.