offset table (centerboard)
 

i am looking for an offset table of yachts' centerboards (keel will be fine)
if anyone have it , please give me any length of the table.
i eager to find it for my experiment for this semister majoring in Fluid
Machanics.
hope to see some helpful replies and websites.

What you are after is the NACA foil shapes. THere is a good free NACA
generator at
http://ourworld.compuserve.com/homep...rg/getting.htm
and here is a good explanation of the numbering system.
http://www.aa.nps.navy.mil/~jones/on...s/panel2/naca/
Keels and centerboards are symetrical so the first number is zero.

"domingo" wrote in message
...
i am looking for an offset table of yachts' centerboards (keel will be
fine)
if anyone have it , please give me any length of the table.
i eager to find it for my experiment for this semister majoring in Fluid
Machanics.
hope to see some helpful replies and websites.

On Mon, 13 Sep 2004 22:32:15 +0900, domingo wrote:

i am looking for an offset table of yachts' centerboards (keel will be fine)
if anyone have it , please give me any length of the table.
i eager to find it for my experiment for this semister majoring in Fluid
Machanics.
hope to see some helpful replies and websites.

The symmetric four digit NACA foils (i.e., NACA 00xx) are all from a
polynomial. You can easily put together a spreadsheet to generate whatever
offsets you want from the polynomial.

Here is the equation for NACA 0020 of chord length c:

y/c = 0.2969 sqrt(x/c) - 0.126 * (x/c) - 0.3516 * (x/c)^2 +
0.2843 * (x/c)^3 - 0.1015 * (x/c)^4

'y' is the extent of the foil to the right of the center line (assuming
it is a vertical foil, as in a centerboard). Any foil you'd be likely to
use in a keel or centerboard will be symmetrical to the right and left of
the centerline.

Note that the 20 in 0020 means that the maximum foil thickness is 20% of
the chord length. Likewise, NACA 0010 has a maximum thickness of 10% of
the chord, and so on.

For other NACA 00xx foils, just multiply all the NACA 0020 'y' values by a
scale factor. For example, for NACA 0010, just multiply by 10/20. For NACA
0025, just multiply by 25/20.

This all comes from NASA Technical Memorandum 4741, which you can find
online if you want to double check me (and you should!).

Have fun!

--Mac