Sydney Hobart

CBTF /canting keels/wings/kFOIL /daggerboards

Matt, thanks. I personally have some reservations about a forward foil hanging out there all by itself but the CBTF guys have told me that if the forward foil was hit on a properly designed CBTF boat it would not stop the boat. It would have an effect on the upwind ability of the boat.
There are other systems that can be used for extra lateral resistance including daggerboards with some new boats putting the daggerboard BEHIND the keel which is can be better for balance. And then there are fixed wings, like ACC wings that Andy Dovell has experimented with very succesfully: if they break off so what? The boat just loses a litte windward ability but the hull and keel are not compromised. My system, the kFOIL uses a wing or wings that retract into the bulb when not needed or when they hit somthing. The kFOIL is totally unproven on ocean going boats but offers a lot of potential. I'm liking the wings-retractable or not more and more because they take up no room in the boat and are easy to handle.
Skandia had what they called a forward cannard but it wasn't CBTF and it did NOT fail in the race. Wild OatsII won the Pittwater Coffs ocean race and it is full blown CBTF....
But no system yet offers the windward ability of CBTF using "collective"....
Back to the original point: when considering/criticizeing/applauding these systems the details really do count and the propensity by some to label all canting keels as the same-and faulty, dangerous ect. is just plain nonsense.

 

How many canting keels fall off of boats that do not race all out in storms, or are never grounded? Well? There must be something else we can improve more than this.

 

Canting keels dont typically fall off if they arent in storms or get damaged by a grounding. The problem with them is that they are only really efficient offshore, where you are more likely to run into a storm than not. You cant build an inshore round the buoys racer with a canting keel, because on upwind legs it wont be able to compete in tacking duels without getting killed. The keels on the big boats, where the concept makes the biggest difference, should be strong enough to stand up to a huge storm- especially if the boat was designed with line honours in the Sydney-Hobart in mind.

 

I'm not sure about that....the canter Skandia beat the other 98'er Konica (a fixed keeler) on the short courses of Hamilton Island race week. She did lose badly on the short races of the Rolex Cup though but IIRC the top boats in that series were Targe and/or Wild Oats which are 60-66' canters.

 

canter/tacking duel

USA2, I'm surprised you'd make such an uninformed comment about canters: Schock 40's do well in tacking duels when anybody get's close enough to get into one-so I'm told. CBTF boats in particular can tack with the best fixed keel boats and then some especially after they figure out how to use collective. And in rc canting keel boats a CBTF or kFOIL boat will tack faster than or equal to a fixed keel boat; keel movement is very quick on most rc canters but the thing that slows some down is when they have a non-moving foil significantly forward of the keel fin. That puts the brakes on everytime they tack.Same thing happens in big boats with forward foils that don't move especially if there is a lot of space between the foil and the keel.

 

it does depend on how long your tacking duels are...But when the keel is swung over it takes about 8 seconds, while on say an IACC type boat they can tack in about 3 seconds, give or take a little. Of course, since the canters are usually just faster than their conventional counterparts, the question would be if they were close. The CBTF boas can turn as quickly as an IACC-type boat, but they cant get settled on their tack as quickly. Im just using the IACC boats as an example..dont know if any of them have ever gone head to head with a canting keeler. Lets say Morning Glory and SUI-64 (Alinghi) squared off on a americas cup course. MG is most likely to lose going upwind because the slower tacking, but downwind she would kill SUI-64 because she can sail slightly higher and a lot faster than the IACC type. this is all just a theoretical situation....

 

CBTF vs ACC

US2, the ACC boat would lose big time in both directions: the z86's have more SA than an ACC boat and upwind they have COLLECTIVE which would guarantee a better VMG even if they didn't have more power.Their greater power is in a rig a lot less advanced than an ACC rig so there might not be a huge disadvantage due to the rig for the ACC boats. But the z's have a longer waterline and collective upwind -they'd cleanup. Especially if the wind was blowing...I'd stay up late for the race ,though...

 

strong winds would mean the Z86's win- not just cuz their hull and rig, but because the IACC would sink

 

how fast does a Z-86 go upwind would anybody guess?

 

z-upwind

Hull speed is about 12.4 and probably wouldn't be exceeded much upwind but down wind it could be nearly doubled -maybe more.

 

and an IACC can go at least 13 upwind.... and tack faster than the Z86. If the IACC covered the Z86, she would be forced to sail long legs to take advantage of her theoretical higher speeed on the wind with more sail area. The IACC could just tack straight up the course. The collective steering does help, but it still takes 8 seconds to swing the keel, which means the IACC boats are tacking on dimes and taking off while the Z86 is coming around slower. I think the IACC would win upwind, based on pointing higher and sailing at least as fast. Off the wind of course is a diffferent question, as the Z86's have more sail and are wider than the IACC boat.

 

ac vs z

Maybe, but you're considering swinging the keel as part of the tacking process and it being max to max. You can start the keel moving before you tack and finish movement afterwards. And a twin foil boat will tack faster than a fixed keel. But the acc rig is a better upwind rig.Be interesting to see. My upwind speed was a guess you know; I'd like to see what the boats actually do.There was a Latitude 38 article with speeds in it but I can't find it....

 

even then, if you start swinging the keel before you tack, the boat slows down because it begins heeling and spilling wind as the rig cants farther over. I dont see how you figure a Z86 can tack faster than an IACC either.. The IACCs are very slow for their size off the wind, but those things are optimized for upwind sailing. obviously these boats we are comparing here have never had an actual head to head match race, but there are very few boats that can match an IACC boat in a full-out tacking duel, and despite the MZ86's being about a foot longer, with more waterline and sail area, the IACCs are more easily turned, because they are built with tacking duels in mind. The Z86's are ocean racers. If you get in a tacking duel in the middle of the ocean, its easier to escape the problem of being covered than if you are inshore racing upwind on a narrow course. I'll keep looking for the actual Z86 upwind speed...

 

ac vs z

I don't know much about the z's but if you look at it logically and it takes 8 seconds max cant to max cant and 4 seconds to turn the boat- seems to me you'd be better off to start the keel two seconds before starting the turn rather than having four seconds of keel movement still left AFTER the turn.
A twin foil boat will manouver much quicker than a standard fixed keel; if you add in the ac trim tab they're going to get closer.
Interesting race; probably happen one day.
By the way, on Chads I see roy doesn't want any discussion of canting keels, movable ballast etc.Funny, I thought that was a "discussion" forum.

 

apparently there are rules on what one discusses there...