C Class Cat vs C Class Monofoiler

This is an early(on SA)comparison I did for a C Class cat vs a C Class monofoiler-just W/SA ,SCP/total weight and SA/ws are considered. The monofoiler would have a lower aspect rig than the cat.....(see second post for L/D comparisons):

There are six rules that define a C Class yacht. In essence, they are (with a slight change):

1) It must be a catamaran,trimaran, monohull or any combination thereof.
2) It must have a crew of 2

3) It must not exceed 25’ in length

4) It must not exceed 14’ in beam

5) It may have up to 300 sq feet of sail area (27.90 M^2)

6) It must have a sail number and the class symbol
============================================
Just for the hell of it I wanted to see what a monofoiler built to the C Class rules would look like-numbers wise. I included trimarans because this thing would have very small pods-somewhere between 160 and 350 lb. of buoyancy. Just to keep it upright when not sailing-and I wanted it legal w/o an arguement.
C Class Monotri
-LOA 25',hull L/B 18-20/1
-Beam 14' incl. carb racks and pods
-SA-300sq.ft. with a CE just below 75% of a C Class Cat/ Problem: designing it with a high enough lift coeficient at a lower aspect ratio.
- main hull beam 1.25'
- Weight Targets: Hull, foils,racks--120lb
Rig- 140lb
All up boat weight:--------- 260lb
Foil Loading@ 80% on mainfoil: 158lb. per sq.ft.
Mainfoil area: 2.93 sq.ft.(take off profile same as Moth-or better with variable geometry main foil)
Note: to eliminate unecessary flap movement caused by wand averaging in chop manual control of the main foil flap would be tried-no wand)
=============================
Rig has to be shorter than the cat version because Monotri RM(including Veal Heel) is only 59% of the cat.
Other comparisons:
W/SA-Cat: 2.26lb (sail loading) Monotri: 1.93lb(sail loading)
Target weight would keep Monotri 100lb lighter than a Cat.
SA/WS ratio flying would be- much better than the cat-in fact only 30% of the cat with the cat flying a hull. And within less than 1% with the foiler off the foils!
----------------------------------------------------
Could it be done? Could it win?
If a legit challenge emerged could/would the rules be changed for a trial run that counted?
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



RM FOR STEVE AND FREDO REFLECTED IN SCP/TOTAL WEIGHT
C Class Monofoiler vs C Class Catamaran--a first look


These are numbers I've come up with that compare a C Class Cat to a C Class Monofoiler:
================================
C Class Cat
-----
A. I found numbers for Invictus: 170kg(374lb) all up ;75kg(165lb) wing, 95kg(210lb) hull,cross beams, foils.
For the purposes of this comparision I reduced Invictus numbers to: 163.63kg(360lb) all up,72.18kg(158.8 lb.) wing,91.44kg(201lb)hull,cross,foils.
Note: on both boats crew CG figured at 1m(3.28') from side of boat(or racks):
Crew weight: 320lb(145.45kg)
B. RIGHTING MOMENT
Measured with boat just flying a hull:
--------------------
1) CB lee hull to boat CG: 6.5'(1.98m)(assume 1'(.3m) hull beam)=RA; 6.5 X 201=1306.5ft. lb/ 1.98 X 91.44=181.1kg/m
-------------------
2) CB lee hull to crew CG:6.5'(1.98m)+7'(2.13m)+3.28'(1m)=RA; 16.78' X 320lb=5369.6ft.lb / 5.11m X 145.45kg=743.3kg/m
-------------------
3) CB lee hull to wing CG: 5.635'(1.71m)=RA; 5.635 X 158.8= 894.83 ft.Lb. /1.72m X 72.18kg=124.2kg/m
========================
4)C Class Cat Total RM:= 7570ft.lb / 1049 kg/m

==============================================
C.----- Total weight: 320+360=680lb /145.45 kg+163.63=309.08
D. CE at 19'(5.79m)
E.
. Bethwaites Ratio: SCP/Total Weight
1)SCP= RM/ CE-CLR
a.-SCP=7570/19=398.42 // 1049/5.79=181.17
2)SCP/Total weight=398.42/ 680=58.6%// 181.17/309.08=58.6%
3) SCP/Total/WEIGHT(STEVE)=61.7%/color]
4) [color="#4169E1"]SCP/TOTAL WEIGHT(FREDO)=61%

F. W/SA=2.26
W/SA(Steve)= 2.53
W/SA(FREDO)=2.46

++++++++++++++++++++++++++++++++++++++++++++++++++++
C Class Monofoiler
Note: crew =320lb(145.45kg)
A. --- Righting Moment
1) Veal Heel adds 1.5'(.457m) to righting arm
2) crew-1.5'(.457m)+7'(2.13m)+3.28'(1m)=RA; 11.78'X 320=3769.6 ft.lb // 3.587m X 145.45=521.73kg/m
3) hull +foils- 120lb X 1.5'=180ft.lb // 54.55kg X .457m=24.93kg/m
4) wing 140lb X 4.5= 630 ft.lb // 63.63kg X 1.37=87.18kg/m
5)C Class Monofoiler Total RM: 4579ft.lb// 633.84kg/m
--------------
B. Total weight=320+260=580lb(263.64kg)
C. CE 13' (3.96m)
D. Bethwaites Ratio-SCP/Total Weight
1)SCP=RM/CE-CLR
a. 4579/13=352.2 // 633.84/3.96=160.06
2)SCP/Total Weight: 352.2/580=60.7%// 160.06/263.64=60.7%

E. W/SA=1.93

++++++++++++++++++++++++++++++++++++++
NOTE: if the hull weight goes up 50lb(22.7kg) then the ratio changes to 56.8%
==============
This is no guarantee of anything-just very interesting numbers.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Also check this out:
This is the intro to a paper by Alan Smith -who helped get the first two person bi-foil monofoiler in history flying:

Proposed Foil Bourne C Class Cat
Challenger 2007

This presentation puts forward an overview of a proposed new generation of C Class Catamarans. It claims that the fitment of an appropriate foil system will result in a SOFTSAIL(emphasis added) configuration being up to 70% faster than rigid wing non foil fitted competition. Some performance information is provided and comprehensive design files exist that justify the claim. It is in effect a wind powered "air" craft with its lifting and control surfaces in the water. The design process employs state of the art aerodynamic performance,stability and control methods.
--------------------------
The presentation can be found here:
http://www.highspeedsailing.com/sailing.htm Note:as of 10/6/08 this extraordinary site is down-maybe it will come back........
===========================================

Thanks to Steve for the info................

Lift drag ratios for a few boats incl. the low aspect foiler rig shown next to a cat below:
Ice Yacht-5.5
Land Yacht-3.8
"Challenger"(Smith design C Class Foiler)-2.8
Cogito-2.0
Int. Moth -1.9
Hydroptere-1.8
(see Alan Smiths site in the first post)

[Chris Ostlind]

Could you put up a link that works, please?

apparently not....