FINENESS COEFICIENT

[iosif gross]

From Ted Brewer:
FINENESS COEFFICIENT (Cf): Also called the Waterplane Coefficient, or Cwp. The Cf is a figure derived from: LWL Area/(LWL x Beam WL). The lower the Cf, the finer the hull at the waterline. Typical sailboats have a Cf of .65-.68
On other sources I am reading that:
A low Cw figure indicates fine ends, a high Cw figure indicates fuller ends.

I know Ted Brewer is an old school designer
What is the forum opinion in the subject?
My question is about sailing boats

Best wishes
Iosif

[Icare]

What do you want to know exactly? The right definition of fineness coeficient or what’s *THE* perfect hull?

For the first point, I leave you search on websites such as Wikipedia.
For the second point, you have to understand you have to find the balance between fineness (sharpness) and volume. The finest hull will be as sharp as a knife blade and will have no storage room inside. The most comfortable hull will be bulky and stubby like a container but will go at sea like … a container. So you have to find the balance point according to the characteristics you’re expecting from you ship.

If you don’t want to go in tiring calculations, I suggest you take the general measurements on a real ship and design its challenger. 😉

[iosif gross]

Hi Icare

Thank you for the answer.
What I have done is what you proposed 🙂
I made a search regarding all the sail boats between 26 to 28 feet that can find data about them on the internet, boats that were designed after the year 2000. Eliminated the extremes and made an average. Changed my design to fall approximately at that average.

I am planning to build first a 3 meter model to try to test some properties in real life.
I know that it will not be an enough good indication, but it is the best I can do (in my opinion) as a private person.

Best wishes
Iosif

[Author]

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