CBTF(Canting Ballast Twin Foil)

Biplane Theory

I'm not sure that the twin foils are in close enough proximity for either biplane theory or tandem wing theory to have much importance in regard to CBTF..

 

A couple of comments

I seem to have come into this thread a long way down the track ...

But I've a couple of comments to add.

Patents

I'm not sure of the patent laws in all countries but I would assume that they're similar. There is usually a requirement that a patent be for an invention that is NEW and is not OBVIOUS to an ordinary person.

When a patent application is filed it is checked against existing patents. If there are no existing patents which covers the invention already then it will most likely be granted. It would be impossible to expect the patent office to check if someone had already come up with the invention but had not patented it.

This means that a patent is effectively enforceable until someone challenges it. It if is challenged then it's up to the lawyers, courts etc to work out if it is enforceable.

In a lot of cases people often decide it's not worth fighting the patent so they pay the licence fee or don't use the technology. It all depends on the amount of financial gain at stake.

As an example in Australia in the late 70s (?) when windsurfing was just taking off the Windsurfer company (if anyone remembers them) took out a patent on windsurfers in Australia, i.e. putting a sail on a surfboard. The other manufacturers challenged the patent. It was shown that people had built windsurfers years earlier. There were photos of one guy who'd built one in the late 50s, early 60s. The court's decision was that the idea was not new and the patent was invalid. In this case there was an obvious (financial) incentive for the other manufacturers to challenge the patent.

In the case of CBTF it would depend a bit on what the courts consider the patent to cover. I haven't got round to reading the patents yet. I know of one sailor (in Australia) who experimented and built a yacht with a canting keel and rig in the mid 70s. No forward rudder in this case. I also know of a yacht with a forward rudder but fixed keel built in England in the 80s (? maybe earlier). A design called a Chanel 31 was designed and built in England post America's Cup 1987 with a canard daggerboard and a swept forward fixed keel. It may ahev even been a forward rudder. I can't remember at the moment. It has been pointed out by others that canting keels have been used on various boats for a number of years. I suspect it will be a case of seeing if someone challenges the patent. I suspect not enough financial gain to make it worthwhile ...

A final couple of points on patents ...

Patents only cover intellectual property for financial gain. There is nothing to stop someone copying an idea for their own use. I could build a CBTF boat if I wanted to and sail it as my own boat. The problem would only arise if I started to manufacture them.

And lastly a patent is only valid if it is enforced. The holders of a patent must take action against anyone who uses their invention for financial gain. If they don't the patent lapses. This puts the boot on the other foot. The holders would have to decide if it's worth their while fighting for the patent ...

CBTF and the rules

Yacht Designers have always been trying to find ways to bend the rules. Back in the IOR days designers like Paul Whiting came up with boats with lumps and bumps designed to push the rating rules to their limits. They produced some quite quick boats as well. I used to sail one of his smaller designs.

The problem came when the designers pushed the rules too far. Then the rule makers made some changes. At one stage centreboard boats were given an advantage over fixed keels. So that's what the designers came up with. Then Paul Whiting and his boat were lost sailing between Australia and New Zealand ... and have never been found. The boat was Smackwater Jack if I remember correctly. A centreboard One Tonner (about 36ft) with all internal ballast.

I suspect at the moment the rule makers are seeing how CBTF goes. If anything bad happens I wouldn't be suprised if they step in with changes.

The other thing which is likely to stop CBTF is the expense. In motor racing rules are often changed to limit costs. Formula one is a good example. If there was no limit to the technology the car probably wouldn't even need drivers ...

Where I sail locally a one-design class became concerned about the spiralling cost as a number of sail makers were coming in and dominating the fleet by using multiple sails. And replacing them frequently. The association rules were changed to limit the boats to two headsails, one mail and one spinnaker per season. Got to admit it makes sail selection a lot easier ...

Unless you're sailing at the top elite level I prefer to sail against another boat and person. Not against a wallet, or expense account.

The Australian Sailing acticle mentioned earlier made a point that CBTF might be well and good for racing yachts with professional crews. But what about the Mum and Dad amateurs who sail Saturday club races?

Hmmm ... sorry about the novel ... but at least I got my money's worth ...

 

CBTF Rules!

I don't think anything is going to "stop" CBTF ;it is simply too good and too fast.
Canting keels have been around for 30 years or so and have hundreds of thousands of ocean miles on them. The biggest concern anyone ever brings up about CBTF is the forward foil-"what if it hits something?" As I understand it the foils are designed to break off with no damage to the boat and whats really important is that the boat can still be sailed!
I think the Schock 40 and the soon to be released Melges 32 have/will demonstrate the viability of the system for these size boats. And there are even smaller boats that may be built using the system.
While maxZ86's have to run the diesel to tack the Schock 40 uses an electro- hydraulic system that operates up to three days on one charge!
As to cost, the CBTF system will add around 5-8% to the cost of a canting keel boat max-which is not too bad for a state of the art technology.

 

Disclaimer required?

I gather from the thread there is a commercial interest involved here. Perhaps should include a disclaimer to that effect ... sorry only joking. Well semi-joking ...

I can think of a few things which would "stop" CBTF

"An incident"

Hopefully not, or at least nothing serious. But losing a keel, the leading foil, having the keel jam, a yacht capsizing ... anything along those lines and various authorities as well as yachting bodies would certainly sit up and take notice.

Rules and Handicaps

I wouldn't be suprised if CBTF boats start getting higher handicaps to reflect their performance against conventional boats. Even if it's just to keep the conventional boat competitive. So I can spend $,000s on CBTF and get a boat which will be 5 minutes faster round the course than a conventional sister ship, but have to give her 6 minutes on handicap ... riiiiggghhhtttt

There was a small article in the paper the other day that entries in the 2004 Sydney to Hobart have to pass a theoretical (computer model?) self-righting test before their entry would be accepted. At least one boat failed the test. I'm not sure if it was a CBTF boat or not. Given that one of the advantages of CBTF is lighter ballast I wonder if they would pass the test? I tried doing a hunt for a website but couldn't seem to locate one. If I do I'll post the addy.

Expense

A CBTF boat is always going to be more expensive to build, maintain and race. The Australian Sailing article mentioned above made mention of what might happen to CBTF at a club level where the owners have limited finances, "volunteer crew" and do most of the maintenance themselves. Additonal expense and complications generally get the thumbs down.


Don't get me wrong. I quite like the technology. I just feel that it may be a bit too "out there" for the average sailor. Perhaps it should be limited to specific events, formats, rules ... whatever.

 

CBTF/ canting keels

Don't know about a "commercial interest",if you were refering to me but I have built and may continue to build a limited number of custom canting keel rc models and a couple of under 20' canting keel proto's. Only one of my models uses CBTF but is in the fight of it's life with the kFOIL that seems to work well in rcmodels.
Now, I believe 100% in CBTF technology for boats over 20' depending on the rule and depending on how full size tests of the kFOIL go. At the present time there is no lateral resistance technology as good upwind as CBTF, in my opinion-but that could change.
See the latest issue of Seahorse for an article by Dave Beck on canting keels and their impact and next months issue will specifically talk about the effect canting keels are having on rigs and on how rating rules are dealing with them.
I believe in the potential of these systems in small singlehanded keelboats as small as 12' LOA and up; in fact the whole area from 12 -20' is wide open for experimentation...
Aircraft accidents in the twenties and thirties didn't stop flying and I don't think canting keels/CBTF will be stopped by any failures that may occur either. It's just too powerfull a technology.....

 

In a previous post I postulated what might happen if an incident occurred with a CBTF boat in a major race.

Unfortunately we may find out sooner rather than later. The latest report from the Sydney Hobart race is that Skandia was abandoned after the keel mechanism failed. The keel has since fallen off and the boat has capsized. All the crew were rescued fortunately.

Other boats have retired, although not in as spectacular a fashion. Targe, the old Wild Oats, was the first boat to retire when they took on water and the electrics to control the keel shut down.

I assume there will be an investigation into the incidents. So we will probably see later what eventuates.

 

Hobart

I don't think there will be any effect whatsoever other than a hopefull one in which the engineering is carefully reviewd.
Many fin keel boats have failed over the years and that has had no effect whatsoever except maybe to improve fin keel boats.
And in this race so far dozens and dozens of fixed keel boats have retired with a wide range of problems including mast failure,rudder failure and structural failures or near failures.
It is interesting to note that Skandia is not CBTF while the old Wild Oats was. The new Wild Oats is still in the race as far as I know.
But the leader of the Hobart race is Nicorrete with a canting keel and most of the Vendee guys-already overhalf way around the world- have canting keels.
This is a serious gear busting ocean race and I don't think CBTF or canting keels as a fast, safe technology will be negatively affected at all.
Hopefully, the engineering problems will be discussed openly so the knowledge gained helps everyone. oh, and Go Nicorrette!

 

Jim Pugh speculates on Skandia failure

WHAT WENT WRONG?
(Yachting journalist Rich Roberts spoke with Jim Pugh, partner in the
Reichel/Pugh design firm, about the problems experienced by Skandia and
Konica Minolta in the recent heavy air Rolex Sydney Hobart Race. Here's an
excerpt from Roberts' story in The Log.)

Pugh spoke cautiously, saying, "I'm not really familiar with the details of
these boats, so it's easy to be an armchair admiral and criticize." That
said, he added: "Skandia is definitely a budget boat. I don't the details
of how the boat was put together, hut I've heard enough the last few days
to make me cringe a little. It's clearly under the specifications that we
would use. From what I hear on Skandia, there are two cylinders and they're
both on one side. They collapsed."

Pugh noted that other canting keel systems are built with two cylinders, or
"rams," on opposite sides and others with only one ram. "It really doesn't
matter," he said. "You just have to make sure the cylinders are built to do
the job. We have three-inch rods with cylinders [on opposite sides]
opposing each other, and they're 17.4 stainless [steel] - very high
strength material." Unconfirmed reports in Australia say that Skandia's
cylinders were only two inches diameter and regular stainless. "Maybe they
don't look at the worst-case scenario with the boat lying on its side with
the things fully extended," Pugh said.

Konica Minolta, the other super maxi that dropped out after suffering
structural damage when it fell off a wave, had a standard keel but also
wasn't up to the conditions. "That boat was engineered by a company in New
Zealand: High Modulus," Pugh said, "[which is] very reputable." But the
builders may have ventured into unknown territory. "That boat has a keel
tower, kind of like an America's cup boat," Pugh said. "Instead of being
bolted to the bottom of the boat, it comes up inside a keel tower to the
deck. It's a way of reducing the overall weight by tying it into the deck,
but it's pretty unusual for an offshore racing boat because it takes up so
much room inside. And when you tie it into the deck, you do run into other
structural problems.

"Even if the keel was done in the traditional sense, you come down [off a
wave] and you're basically trying to break the back of that deck. But when
you put that keel tower up there, you also have some loads being thrust
into the deck. "It broke just in front of that, right across the deck,
between the front of that keel tower and the mast, and apparently there
wasn't much in the way of fore-and-aft structure in that area."
- Rich Roberts, The Log, full story:
http://thelog.com/news/newsview.asp?c=138717

 

I was interested in the Schock 40 (still am really). The Canting Ballast Twin Foil technology apparently can be maintained with stuff you can purchase from any hardware store and golf cart motors are used. I chatted with a dealer and he suggested that I might be unhappy with the motor. When you spend more than 180,000 for a boat, even a sail boat, you expect more than a 15 HP motor. This is a safety issue as much as a convienience. I discovered that the Schock 40 can not support more than a 15 HP motor.

There is not as much weed in my sailing area as in other places but the CBTF technology (indead any bulb keel design) suffers from that unless a weed cutter of some kind is incorporated into the design. That issue was addressed in the Schock 40. The issue of knocking out the forward rudder on a dead head was not addressed. I became worried about that since we often find ourselfs out after dark and do occasionally bump into them. This has happened only a handfull of times over 6 years so I suppose if the rudder were inexpensive to repair it wouldn't be a big deal. Is it?

Anyway, would LOVE to bare boat charter a CBTF boat. Can they really sail Directly into the wind? I mean this is hard to believe is it not?

 

Cbtf

MG-I realize(hope) you MUST be kidding but of course a CBTF boat can't sail directly into the wind but it can have a better vmg to windward than most other boats by the use of the collective which allows both foils to be turned in the same direction....See the discussion on gybing daggerboards.

 

Yes Frank, they can sail directly into the wind.

 

High Mighetto
Van you say over speed of SHOCK 40 under 15 HP motor?

Regards Gina

 

In a CBTF boat, do the "twin foils" have to both move? Skandia had two foils, along with her keel. One of those foils was a daggerboard that just went up/down. do the CBTF boat have twin rudders, or do some of them have rudders and daggerboards?

 

Cbtf

Foils on CBTF boats are located at more or less specific points along the wl.(approx. 25 and 83% aft of the bow/wl intersection on full size boats -if I remember correctly. These positions are important for reducing wavemaking drag on fullsize boats). Skandia was NOT CBTF..
The originators of CBTF call the twin foils foils instead of rudders because most of the time they are used to develop lateral resistance not to steer. Both foils turn in opposite directions to steer and both turn the same direction upwind when "collective" is used. Collective allows leeway relative to the hull to be dialed out and to be changed for various conditions.It relieves the canting keel strut from generating lateral resistance.CBTF is probably the best upwind canting keel system on full size boats.
On rc models(saw your posts on a couple other forums) CBTF runs into problems because some of the "tricks" used to reduce wetted surface on full size boats don't work well on models like high aspect foils and thick strut sections. None the less collective is a powerfull upwind tool that has potential on a properly designed model. A possibly better system on models is the kFOIL.
On models because you can either keep the sail area the same and reduce displacement or increase sail area and keep displacement the same there is a problem with some high performance canting keel models downwind where the canting keel does no good and the extra sail area and/or lower weight can lead to pitchpoling. So on models -at least racing ,high performance boats in the F100 class-it may pay to have a portion -25-35% -of total ballast(incl. battery) in an on-deck rack designed to allow the weight to move side to side AND fore and aft-powered by the same winch used to cant the keel.It's a hybrid system where the keel cants and some weight moves on-deck-very efficient and reduces or eliminates pitchpole. You can't put all the weight in a on-deck system unless you have a way to right the boat from a knockdown/capsize.(see Aquataur models)
Anyway, good luck with your model...

 

thanks for explaining that