Open source 12-15m high performance/semi-cruising catamaran design

Well before that, if you read the posts back in page *i cant be bothered finding it* you would have already known what the design was aiming to achieve...

% lift vs displacement - i dont know for sure yet, thinking 50% at 20kts SOG, but it requires a comprehensive analysis to determine what compromises, if any, are required to be made with respect to light wind vs high winds, upwind vs downwind, running 1 board down vs 2 boards down its all pretty complicated to get it right so the boats average speed is optimized on all points of sail and in different wind conditions.

Using your diagram you say we have 147 degree foil angle for the tip - this gives us bugger all vertical lift as a % of the total foil area, i cant be bothered doing the math on the sin or cos of this angle right now. But my point is this, and always has been, you can achieve this same low % lift per foil area number using C boards, AND accomplish the same net result without the complexity and lost interior space of that huge trunk youve shown. You also dont need to build such a complex trunk with shrouds covering the huge opening at deck level and a complex foil control mechanism which allows 2DOF movement in the top daggerboard bearings. C boards only need 1DOF. So all in all, for this application, the C boards are winning hands down and is why i said your idea of Z foils in this application are completely IMPRACTICAL - in response to your very first Z-foil contribution to this thread!

 

You don't know what you're talking about........

 

Well prove it Doug - ive designed, built and sailed REAL boats, 2 of which documented on this forum - perhaps its time you went back to designing and playing with your toy boats like the one of which you posted videos of and looked incredibly unstable and could not stay on its foils for more than a few seconds? Since then, no more videos of this incredible machine - why?

 

G. first rough view of C-board down and up. +max lift?

 

Exactly- and this is probably too much curvature and will generate too much lift and not enough leeway. Thus it could be straightened a bit to get the right balance of both...

 

flatter then

 

Bill did post the ORCA weight ready to race somewhere , but I can't locate it.

From memory it is up around 6 tons. I'm sure Bill would tell if you asked over on SA

The very low figure banded around is just the hulls minus rig etc.

Not sure the G force is really designed to carry much of a cruising load.

Found this whilst looking. Looks like big powerful engines will be a requirement of any 300 mile per day boat.
One would never consider Wahoo a 300 NM/day boat even though it has accomplished this feat.

From another forum posted by Bill.

"After 14 years of coastal racing on 52' Afterburner (fastest coastal cat on the west coast) I can claim to know something about wet uncomfortable fast sail boats. I just finished the deliveryon my new cat Wahoo from Tortola to Ensenada (Ventura soon). Wahoo is a fast cruiser, a carbon Schionning GF 1400. At 47' she is light in accomodation, with 2 queen cabins, 2 fore single cabins, one head, one galley and a salon/bridgedeck cabin. She has 2, 21hp diesels. We had one 300 nm day in the trades with way too much sail up all night. 200+ nm days in the trades were easier. In the Pacific it has all been up wind and motor sailing. We had 13 hours sailing doing 11-13 North of PV. Hit 20 surfing in the Atlantic and in squalls in the Pacific. Mostly 6-8 knots motor sailing in 5-12 knot headwinds. We did a bit under 6 days Chiapas to Puerto Vallarta, one fuel stop in Acapulco. And a bit under 6 days PV to Ensenada, one fuelstop in Turtle Bay. We were blessed with good weather."

 

I pulled the 7.3 tonne figure from the measurement data om one of the races one of the sig45 entered along with the OMR rating...

Edit: got confused wahoo with the sig45... fixed above

Do we know the sail areas of wahoo? Is it standard sail areas as per schionning g14 design? The sig45 has a substantial rig on it which helps it along...

 

Believe that Fujin has only the C-foils (no dedicated daggerboards) for lee resistance.

 

In response to the "toy boat" post by "groper", post 213:

Fire Arrow is a revolutionary design for a foiling trimaran and is the first tri of any size to use UptiP ama foils and the first to use an actively controlled foil on the daggerboard giving her two independent altitude control systems. The boat is designed to fly at a 10 degree angle of heel ,keeping the windward UptiP foil clear of the water. Fire Arrow is the only foiler using UptiP foils that does not have to retract/deploy the windward and leeward foils as is required on cats and others seeking to take advantage of these remarkable foils invented by TNZ in AC34. The Fire Arrow Foil System allows for a drastic reduction in crew workload while allowing all the advantages of the UptiP foil-including automatic altitude control not tied to speed like a surface piercing foil.
Her actively controlled daggerboard foil on the oversquare platform is capable of drastically increasing RM automatically with downforce. Further, she uses Two Stage Planing Amas for the first time on any trimaran in history.
Testing was started in June of 2014 and completed on July 24th 2014 with the foil system working perfectly. On that day she did twice windspeed in conditions with very light air(5mph) and relatively big waves leftover from a southerly .
In 2016 the first fullsize tri, Maserati, using the basic elements of the Fire Arrow Foil System sailed for the first time. She put over 6000 miles on her daggerboard foil and won the Malta race(due to an error by Phaedo) and was second by 12 seconds to Phaedo after 600 miles in the Carribean 600. In both those first races Maserati was short one third of her foil system due to a collision with a ufo. In July this year, Maserati ,using her version of the Fire Arrow Foil System designed by Guillaume Verdier, will race against Phaedo in the Transpac-this time with her foiling system at 100%.
The Fire Arrow Foil System is being incorporated in the design of a 15' trimaran 18' wide-WOLF-daughter of Fire Arrow. Follow development here:
High Performance MPX Foil/Self-righting Trimaran-The Test Model https://www.boatdesign.net/threads/high-performance-mpx-foil-self-righting-trimaran-the-test-model.36058/page-171

 

Weirdest 15m open bridgedeck catamaran ever! Must be the camera angle.

 

Congratulations Doug - you have successfully achieved what no other poster on BDnet has since the forum was upgraded - my first IGNORE button addition.
For those looking to find the ignore button - click on the posters name and in the pop up you will see "ignore". Once you click it, like magic you dont see anymore posts from that person on the forum... wonderful peice of technology

 

Weight summary attached. Its not finished and have not included the moment calculation for CoG yet and some of the values are estimated rather roughly a this point but you can see where this is going and it may help others in their design process... ill update it once ive finished it...

 

Groper, easier to get pitch authority via the rudders than the c-foils. Fujin appears to have no canting tackle for the boards. Lee resistance is also via the c-boards? Looking promising.
Project 38 ring any bells? Your list of sundries is very depressing. Lines 34-57. Nothing appears to be excessive but total wt is 1700 kg. Engine data includes G/B sail legs?
Of interest, how much do you budget for connective structure?

 

That weight analysis is nice, thanks for posting, that will help me do mine. Your design is extremely light!