I'm playing with the design of a 15 ft solo cruising sailboat, well for
weekends and short vacations anyway. I'm trying for as much freeboard as
practial to get interior headroom, plus a small cabin. I'd like to know
how to calculate the extra sail area and lateral resistance to compensate
for the extra freeboard. Is there a rule of thumb, easy formula, or some
sort of approach? I know how to calculate sail area and lateral resistance
when hull windage is ignored, ie the usual displacement, wetted surface,
and sail area ratios.



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William R Watt National Capital FreeNet Ottawa's free community network
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William R. Watt ) writes:
I'm playing with the design of a 15 ft solo cruising sailboat, well for
weekends and short vacations anyway. I'm trying for as much freeboard as
practial to get interior headroom, plus a small cabin. I'd like to know
how to calculate the extra sail area and lateral resistance to compensate
for the extra freeboard. Is there a rule of thumb, easy formula, or some
sort of approach? I know how to calculate sail area and lateral resistance
when hull windage is ignored, ie the usual displacement, wetted surface,
and sail area ratios.


I found some of the information I needed at the Ottawa public
library in a book called "Sailing Yacht Design" by Henry and
Miller (1965) which has a graph of freeboard vs waterline beam for
boats from 5 ft to 50 ft in length. It has a other useful graphs,
all summarizing scatterplots of data from a number of boats. The
graphs don't completely anser my questions but they do let me know
if my design is 'way out of line with boats that were being sailed
at the time. My design has mostly conventional ratios although
near the limits of some.

I also found another interesting book, "Sailing Craft" edited by
Schoettle (1928) at the public library. The articles, written by
various authours, covers many kinds of small boats, most with lines
drawings. It has chapters on sneakboxes and sailing canoes.
--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned

If you want the definitive book on the subject check out this auction,
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3558418287

"William R. Watt" wrote in message
...
William R. Watt ) writes:
I'm playing with the design of a 15 ft solo cruising sailboat, well for
weekends and short vacations anyway. I'm trying for as much freeboard as
practial to get interior headroom, plus a small cabin. I'd like to know
how to calculate the extra sail area and lateral resistance to
compensate
for the extra freeboard. Is there a rule of thumb, easy formula, or some
sort of approach? I know how to calculate sail area and lateral
resistance
when hull windage is ignored, ie the usual displacement, wetted surface,
and sail area ratios.


I found some of the information I needed at the Ottawa public
library in a book called "Sailing Yacht Design" by Henry and
Miller (1965) which has a graph of freeboard vs waterline beam for
boats from 5 ft to 50 ft in length. It has a other useful graphs,
all summarizing scatterplots of data from a number of boats. The
graphs don't completely anser my questions but they do let me know
if my design is 'way out of line with boats that were being sailed
at the time. My design has mostly conventional ratios although
near the limits of some.

I also found another interesting book, "Sailing Craft" edited by
Schoettle (1928) at the public library. The articles, written by
various authours, covers many kinds of small boats, most with lines
drawings. It has chapters on sneakboxes and sailing canoes.
--
--------------------------------------------------------------------------
----
William R Watt National Capital FreeNet Ottawa's free community
network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-freenet email must have "notspam" in subject or it's returned