The best single look at the fine/fullness of a hull is by calculating
the prismatic coefficient. This is a little complicated, so hang on:
a) determine the area of the largest midship section of the boat.
Multiply this by the waterline length. This gives you the volume the
boat would displace if it were as full as possible -- no taper at all,
bow or stern.
b) take the actual displacement volume -- usually you can get this by
dividing actual weight (not registry tons) by the weight of seawater
in the same units (64 pounds per cubic foot or 1025 kg per cubic
meter)
Divide a/b and you get a percentage. The naval architecture books
will tell you what the ideal prismatic coefficient is for boats at
each speed. It typically runs around 54% in displacement boats in the
size we usually talk about here.
Fintry's PC is 58.6%, a little larger because she's a little larger
boat. During our search for Fintry we turned down one boat,
Flintstone, primarily because her PC was very high. She was very
spacious, but would have had very high fuel consumption and been
uncomfortable. see <a style='text-decoration: underline;' href="http://www.mvfintry.com/boatsnotbought.htm" target="_blank">http://www.mvfintry.com/boatsnotbought.htm</a>
Steve's comments about "U" and "V" shape are only half the story --
you have to look at the plan (top) view as well as cross sections.
Jim Woodward
<a style='text-decoration: underline;' href="http://www.mvFintry.com" target="_blank">www.mvFintry.com</a>
stevej <vtboat RemoveThis @sover.net> wrote in message news:<3F9FE79F.2000504 RemoveThis @sover.net>...
> As an amatuer boat builder, not having been properly schooled in the
> mathamatics of nautical architecture, I would offer the idea that,
> in general, a full ended hull would have a "U" shape to the cross
> section at or near the waterline entry point and a fine ended hull would
> have a sectional shape that is "V" shaped at the waterline entry.
> The relationship of the sectional area at the waterline entry to the
> flair and/or fullness of the bow is something that has provided me with
> countless hours of thought and speculation. To reduce it to a numerical
> quantity would seem to take the fun out of it.(just my approach)
> I have been particularly intrigued with the effect
> that these shapes have in controlling bow lift and boyancy and the
> effect of throwing off spray with small boats...canoes, kayaks, etc.
> The bow shapes of several of the designs of L.F. Herreshoff seem to have
> mastered this effect and his balancing of fineness and flair at the bow
> apparently work very well for the particular conditions designed for.
> If you have access to the book "Sensible Cruising Designs" , look at
> design number 98,"Rozinante" and design number 101"White Water Racing
> Canoe" to see two variations on this idea.
>
> Pablo wrote:
> > Hi,
> >
> > I would like to know what is the difference geometrically between a full
> > ended and a fine ended hull? I was reading the John Winter's webpage
> > (http://www.greenval.com/jwinters.html#technical%20articles) Part1
> > (Frictional resistance) in the effect of shape section and could not
> > understand what was the difference between these two types of hull. If you
> > have an image that could help me understand it would be great. Thanks for
> > your help in advance.
> >
> > Pablo
> > remove213 for mail
> >
> ><!-- ~MESSAGE_AFTER~ -->
>> Stay informed about: Full and fine ended hull 
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