Update

A couple of images from a busy shop. Our new website is nearing completion so more detailed info will be available soon, on our UAV work especially, as well as the ongoing foiling sailboat projects.

Limiting

Ongoing testing with different foiling configurations is confirming that ultimately righting moment will determine top speed.

The diagram below nicely illustrates what happens as speed builds.
The plot takes a constant true wind angle (heading relative to true wind direction). As boatspeed increases, the component of apparent wind from dead-ahead gets bigger, while the true wind velocity stays constant. Therefore the wind we feel on our sail moves progressively further forward.

Diagram taken from the interesting article here:
http://boards.co.uk/how-to/how-fast-can-we-go-the-science-of-speed.html#AmZd7dgCcvAEmL31.97

As apparent wind direction moves forward, we have to sheet on in order to keep an angle of incidence between sail and apparent wind. But moving the boom closer to the centreline increases the component of sail force that wants to heel the boat over. For the same sail force, drive decreases and overturning moment increases. Hence we need righting moment to resist the added heeling moment.

On the left we have the boom eased and the sail twisted. Sail force (orange) is mostly directed forward.
On the right the boom is near centreline and the leech is tightened by sheeting on.
In these diagrams sail force is identical but the component to leeward (responsible for heeling moment) is much larger when the apparent wind rotates forward.
In reality, when the apparent moves forward, it also increases in speed. So sail force would be larger, exacerbating the problem. 

It is inescapable that we must be able to get all our upward lift from our leeward foil if we ever want to be able to efficiently foil upwind. Also if we want to foil in light airs downwind, and if we want to keep pushing max speed downwind in fresher conditions.

Recent work with AC45 Turbo test platforms, and smaller cats, has shown that differential rudder rake, such that the windward elevator foil produces downforce, can add significant speed.
It may be that using the windward foil to pull down could pay, bringing about a return to four-point systems.
But it is certain that span restrictions that require multiple surfaces to get sufficient lift on the leeward side are driving development to a dead-end. If such restrictions persist, more changes are inevitable as people invent elaborate rule-cheats such as having several foils in each hull.
Much better to encourage simplicity.

Mostro del Garda

Congratulations to Marvin Baumeister for winning the Foiling Week regatta for kiteboards.
He used (for the first time) an all-new foil package (vertical, fuselage, and horizontals) created with project and design co-ordination by Carbonix. CFD and optimisation was by D3 Applied Technologies. Tooling design by Carbonix...

Critical Mass

Interest in our L foil kits has been overwhelming. We are at full capacity fulfilling orders and have additional tooling in the pipeline to shorten lead times. Will be sure to publish more images and detailed specs as soon as we get a chance.

Market demand speaks clearly and people are 'voting with their wallets'. Customers who want the best solution within the original A Class box rule far outnumber those willing to invest in complex rule-cheats, chasing a moving target.

Other manufacturers are also gearing up to match demand for ‘non Rule 8’ foils. A wise investment on their part. Having more products on offer is great. Whether competing or complementary at different price points, the result is more choice for the sailor and a healthier fleet.

Solutions by manufacturers and private builders don’t just include L/V inserted-from-below designs, but also Z/Hydroptere type foils with longer span and less tortured angles. 

Every configuration has strength and weaknesses. Personal preference plays a part and competition will further inform us on how the performance envelopes overlap. What they have in common is the pursuit of efficiency unshackled from arbitrary chains.

For now this means we are heading to the absurd situation of a majority of boats being considered illegal in official events. Naturally the result would be reduced participation. Fortunately initiatives such as that spearheaded by the USA and Canada are smoothing the road for a sensible adjustment.

Leading sailors have expressed their support. Those who have experimented and want others to share the experience are in favour of allowing the design freedom to make foiling easier and safer.

Every A Class sailor must now be sure to make their vote count. Let our elected committee members fairly represent the reality on the beach and finally allow progress to flow.

Pic courtesy Sentient Blue Team showing a 2007 A Class platform retrofitted with Carbonix 2014 foils and rudders.

Insight

Some thoughts following some recent testing with a focus on handling.
Specifically, we worked to gain data on how different foil configurations affect dynamic behaviour during turns in strong wind.

The results confirmed observations we hear regularly from experienced Moth sailors, as well as those who race foiling multihulls such as the NACRA F20 Carbon FCS:
Being foilborne on the upwind leg makes the bearaway a lot safer.

Intuitively it is easy to understand that a foil has the ability to 'push back' with increasing force as the bow-down moment from the rig increases. But this is only part of the picture.

In displacement mode, an increase in bow-down trimming moment must result in some bow-down trim in order to move the centre of buoyancy forward.
More volume has to be displaced closer to the bow so that a restoring bow-up moment can exist to counter the increasing bow-down moment from the rig (which in turn is a result of sail force increasing and rotating to point more forward during the bearaway).
A secondary effect of the bow-down trim is that the rig increasingly pushes down, effectively increasing displacement.
All the while drag is increasing, speed is diminishing (or increasing at a reducing rate), and available volume (forward buyancy) is running out.

Staying on the foils instead allows the foil/elevator system to dynamically counter the changing sail vector.
Less obvious, and possibly more important, is the fact that, with less drag and smoother acceleration, the apparent wind stays forward so bow-down trimming moment is much smaller.

To reap the benefit, foiling upwind has to be competitive.
This can only be the case when maximum righting moment is available.
To maximise righting moment the leeward foil must be able to carry the boat at moderate (upwind) speeds and give some heave stability unaided.

Safety is perhaps the most compelling argument for ending the absurd restrictions imposed on the A Class by a shrinking minority.

Images of customers who have retrofitted our L foils to existing (mostly older) A Class cats.
A low-cost upgrade that increases performance and improves handling.
Incidentally it makes beach launching easier, as the foils support the hulls, giving a small point of contact rather than potentially scratching a larger area. Obviously it is better to always use a set of 'beach wheels'... But where laziness or circumstances do not allow it, the foils make for less widespread damage.

Imagineering Part 2

In Part 1 we looked at straight line sailing.
We concluded that foils will always be a hindrance at very low speeds, but will give an advantage at higher speeds. More aggressive setups (read more foil area) are even worse at low speed but, since they allow earlier takeoff, become superior 'sooner' (at a lower windspeed than more moderate foils).
The exact crossover is still being explored. It may depend on crew weight, hull characteristics, and rig choice.

Tacking and Jibing

When we introduce changes of direction the picture gets more complex.

Re-Configuring 

As a general rule, asymmetrical setups are always faster in a straight line.
Water ballast, canting keels, and sail 'stacking', are all examples of how making a boat asymmetrical improves performance on that tack. They offer gains additional to just moving crew weight to windward. At the extreme, all-out speed record craft have been 'permanently' asymmetrical for some time now.

Configurations with all the lift on one side (those that maximise righting moment) necessarily require foil settings to be swapped as the wind changes side.

We can view asymmetry as a form of specialisation.
If we must tack frequently, and our crew resources are limited, the advantage of specialisation must be weighed against the cost of transitioning from one specialised setup to another.
Two or three seconds may be lost during the tack as the sailor hauls on a foil-control line before settling in to sail the new course.
That time must be recuperated via extra straight line speed just to break even. If the distance between changes of direction is too short (because of course restrictions, shifts in the breeze, or tactical considerations), then the faster asymmetrical setup will not pay.

This tradeoff is hard to quantify on the drawing board.
Obviously sailors with more practice will be able to manage such changes more readily.
Once everyone reaches the same level of proficiency, the more symmetrical solution will still free up hands and mental capacity, making maneuvers faster.

Z foils are a compromise in a straight line, but still require management during turns. Differential rake gives a marked improvement (unloading the windward foil to minimise righting moment loss). Since foiling upwind with them only pays in rare conditions, retracting the windward one is de rigueur.

If regular raising and lowering is required, then the straighter the foil, the easier.

As an aside, configurations with an active central T-foil, such as used by Moths, tend to have the sensor wand offset to keep any wake it produces away from the vertical strut of the main foil.
Since T foils rely on windward heel to vector lift from the fully submerged foil, the wand needs to be reset on each tack.
For example, if the wand is mounted to the right, it needs to be set lower on port tack and higher on starboard tack.

Even under an open rule, a central T foil solution will most probably not be the fastest on a cat, because it would effectively halve the beam of the boat, giving up too much righting moment.
The ease-of-use advantage would probably not outweigh the loss of righting moment for this particular almost completely symmetrical configuration.
Though it would be an interesting experiment, it makes little sense to give up half the leverage available to competitors who fully exploit the inherent advantages of a catamaran platform...

In summary, some form of asymmetry, and associated extra work, will most probably be accepted as worthwhile for maximum performance around the course.
The question is how much. Where does the best compromise lie?

Gliding

If we equate straight line sailing with powered flight, then tacking and jibing is like gliding.
During the turn, as sail drive force dips through zero (and below if the apparent wind goes around the front), the distance available before 'splashdown' is analogous to glide ratio.

There is an established and fascinating body of knowledge around unpowered flight.
One of the first facts to digest is that lift-to-drag ratio is the dominant element.
For the same configuration, a heavier glider will fly faster, but it will follow the same glide path (same sink for every unit of forward movement).
It will reach the ground sooner, but in the same place.

So, all things being equal, foils with a better lift-to-drag-ratio will keep us foiling further than less efficient ones. Regardless of crew weight.

In our case, the mechanism that controls heave will also be making the foils work harder as we sink. Surface piercing foils will be getting bigger with sink. Active foils will be lowering flap, and hence increasing lift coefficient. In both cases drag will be increasing. At some point drag will increase rapidly, taking us away from best lift-to-drag regime and shortening our glide.

One possible exception to this is L foils. Since they rely on leeway for heave control, and because mid tack/jibe there is no sideforce, they will possibly remain more efficient for longer, increasing our chances of getting through the turn without ditching the hulls.

In all cases the area of vertical shaft in the water will be getting bigger as we slow down, adding drag.
But this effect should be similar for all configurations.

One interesting take-away is that flying higher helps with maneuvers since it gives you more potential energy going into a turn.
But flying high means long foils, which are draggy at low speeds.
Ultimately an answer could be 'jacking up' the boat just before a turn. But realistically this is not a workable solution for a singlehanded boat...

Dynamic Effects

A fascinating observation we made when testing 'four point' foil configurations (Zs and active/flap foils) on A Class cats is that turning can induce significant rolling.

The cause is simple: as you turn, the foil on the outside of the track travels faster through the water, so generates more lift.
If not managed, such rolling can make the outside foil breach the surface, which then causes a splashdown of that hull.

On a boat where crew weight is so influential, this effect can be managed through good technique.
Inherent heave stability helps.

Side View Vs. Top View

Finally let's examine getting away from a 'parked' position near head-to-wind.

When looking down on the boat, we want the foils to be at or just behind the centre of effort of the sail. Thus when we ease the sail, the drag from the rig tends to just lead the foils. Combined with steering input and windage on the bows, it allows us to bear away quickly and power up.
A boat with less lead will rely more on rudder sideforce to sail in a straight line. This theoretically reduces induced-drag, but takes away 'reserve' rudder force available to bear away.

In side view we want the lifting foils to be slightly ahead of the centre of gravity of the boat. This increases tail volume and helps with stability.

The ideal position for the main lifting surfaces is forward of that for the verticals. Moving the vertical part of the foils forward makes it more difficult to bear away.
Raking the foils bottom-forward helps (and discourages ventilation), but the longitudinal displacement is minimal.

Again a compromise is required if we want to continue using a single sail.
Again our ability to aggressively trim the boat by shifting crew weight is our friend.
Having the windward foil raised does help in this respect, scoring another point for an asymmetrical setup.

Crystal Ball

There is certainly a lot still to learn about how all these sometimes conflicting factors should be balanced for best performance around a course.
Experimentation and time will give us answers, as well as showing us new questions.
This is why we like to play in a development class.

It will be a close run thing between 'four point' and 'three point' solutions on the A Class given our unique characteristics of limited beam, modest sail area, and singlehanded crew.
Our testing indicates that, especially with more transverse span available, L foils show a lot of promise. The near future will most probably be an L or a less tortured Z.

It is doubtful that radical and/or impractical sulutions, such as central foils, and/or ones that require capsized launching, will take root.
There are certain inherent advantages in a cat class that make foil retraction attractive. Just as using beam to generate righting moment is advantageous.

Everyone will weigh the pros and cons. Given the freedom to experiment, the cream will rise to the top and the best ideas will win.
Afterall, this approach has given us the simple, lively and enjoyable toy that is the modern A Class cat.

Bravo

Congratulations to Sergio Vela, who placed third at the European Spring Championship, using retrofitted Paradox 2014 steering system. Full results here.

Image source: Circolo Vela Arco

Imagineering Part 1

In response to questions about where catamaran foil design may go in the future, especially if rule constraints are relaxed, here are some thoughts on the incentives driving design choices.

If our goal is fastest time around a windward/leeward course, then the considerations are:
- VMG upwind.
- VMG downwind.
- Control at low speed, specifically to bear away and accelerate off the start line.
- Speed profile through tacks.
- Speed profile through jibes.
- Sensitivity to setup.

VMG Upwind

To get to the windward mark first, we want the right combination of speed through the water and heading angle to the wind.
We can sail faster through the water by footing. But sailing at a bigger angle away from the wind direction means covering more distance for the same ground gained toward the mark. So our extra speed must be enough to make up for the longer course sailed.

Any form of foil assistance will involve an initial drag penalty.
At very low speeds the foils do nothing but add drag.
As we go faster and the foils begin to produce lift, they contribute even more resistance. This is added to the drag of the hull(s) that are still in the water.

The 'foiler' will remain at a disadvantage until enough weight is transferred to her foils to at least reduce hull displacement-to-length ratio enough so hull drag reduces enough to make total drag of foils+hull lower than just hull drag would have been with no foils...

At any speed above such crossover, all other things being equal, the foiler will have less total drag than her displacement counterpart. Less drag for a given speed means that speed can be maintained with less sail force.
The advantage will get bigger as speed increases.
At some arbitrary point the hulls will be completely free of the water, hull drag will go to zero, and the only contribution to hydrodynamic drag will come from foils and rudders.

Indicative graph showing how drag rises with speed. Simple displacement hull has the least drag at lower speeds because the drag of foil-assisted and foiling boats at those same speeds is hull drag + foil drag. Foil assisted shadows displacement but has less drag at high speed because the effective displacement of the hull is reduced. Aggressive foils pay an initial drag penalty for early takeoff. Note that takeoff constitutes a quasi-discontinuity in the drag curve. Foils are shown 'loaded'. Reducing their angle of incidence at low speed would reduce their drag, but the assumption here is that takeoff is being attempted. 

From the above paragraph we can conclude that a foiler needs to be moving fast through the water to get an advantage. After all, foils don't work unless they have water flowing over them.
So we can conclude that foils will only give us a winning edge upwind if they are efficient enough to support enough weight to significantly reduce hull drag (or better yet eliminate it completely) at speeds that are achievable without having to give up too much pointing angle.

Looking at foil drag alone, this explains why angled and C foils are formidable upwind:
They have negligible extra area compared to a straight foil that just contributes sideforce.
But through curvature or cant angle, they vector some lift upwards, and reduce hull displacement with almost no foil drag penalty.

In contrast, a foil with a dedicated lifting surface (such as an L) must have the same area in its vertical shaft as a conventional foil in order to provide sideforce. The horizontal leg is extra. It just adds drag until speed is high enough for the lift to start making a difference.

Angled and C foils, for foil-assisted sailing, have little more area than upright ones.
Dedicated lifting foils such as Z (centre) and L/V (right) have considerably more.

So now the question is:
Can I go fast enough, enough of the time, to get my dedicated lifting foil working, without reaching away from the top mark too much?

To answer that, we have to look at other speed-producing factors.
Upwind the dominant one is righting moment.
Assuming enough wind to be fully 'powered up', more righting moment means we can keep increasing sail force without capsizing.

If boat mass and crew weight are the same, the only way to increase righting moment is to get more leverage. Meaning lengthen the distance across the boat between the centre of gravity (CoG) and the point where the mass of the boat is being supported (let's leave out downforce from the windward foil for simplicity).

For a displacement cat, flying a hull moves the centre of buoyancy (CoB) to the leeward side, maximising the lever arm.
For a foiler you can see that ideally we would want all our lift to be centred right under the leeward hull.
Any movement toward the centreline carries a penalty in righting moment.
However some compromise may be optimum for an L foil because increasing the span of the horizontal leg (making the aspect ratio higher) improves foil efficiency.

Single foil to leeward (blue), with straight vertical and short horizontal, gives maximum leverage.
Curved vertical and long horizontal (red) gives less lift-induced drag.
Some compromise (orange) is usually the fastest solution.
Z foils may add less drag at lower speeds but will also reduce righting moment.

Given no other constraint, getting all our lift from the leeward foil would be ideal.
If the rules limit the available span on each side, then one foil may not be enough to get our desired 'breakeven' speed to make foiling work.
Then we can go to 'strange' solutions, like having two or more foils on the same hull...
Or use the windward foil to help by contributing some lift.

Since the windward foil is adding to heeling moment, lift generated under the windward hull is very 'expensive'. It has a direct cost in sail carrying power.
That is why Z foil A cats feel very 'tippy' when set up for maximum lift.
It is also why boats like Hydroptere go for extreme beam.

Once fully foiling, stability will come into play.
There must be a way to keep lift constant as speed and ride height change.
This can be done by:
- Varying immersed foil area (surface-piercing foils).
- Coupling lift with leeway (L/V or 'acute L' foils).
- Active control systems (wands/flaps as on a Moth).

Heave stability is not so critical upwind because boatspeed can be controlled relatively easily by coming up into the wind in the gusts, and bearing away in the lulls. Effectively sail force can be kept constant as apparent wind varies.
Pitch stability is surprisingly important upwind because drag from the top of the rig tends to make the sterns squat down, so rudder winglet (elevator) lift is critical.

VMG Downwind

Initially it would seem that downwind the tradeoffs are simpler: Righting moment is less vital because the sail force vector can be more in line with where the bows are pointing.
This is true in strong wind, at low to moderate boatspeeds. In such circumstances, you can sail 'deep', with the apparent wind over your shoulder, and sails eased. Crossover boatspeed can be reached easily and foiling pays thereafter.

However, as boatspeed increases, and the apparent wind goes forward, righting moment again becomes king. Even downwind.

Getting to takeoff speed is also just as critical downwind in lighter conditions.
If there is not enough wind for the sail to basically 'push' the boat to takeoff speed, then we need to luff up to a reaching angle to get sufficient boatspeed.
This is taking us away from the bottom mark. So the speed gain when foiling has to be enough to repay the extra distance traveled in our attempt to 'unstick'.

Again, the tradeoff becomes about how efficient the foils are. We want to be able to accelerate to takeoff speed, despite foil drag, at the 'deepest' possible heading angle, to keep our VMG up.
Once foiling, since overall drag is less, we can improve VMG by sailing broader than a displacement boat, because the necessary drive force is less (drive must oppose drag to sail at a constant speed).

Summary

At low speed foils are a handicap.
To lower takeoff speed we want big dedicated foils, but we want them to be efficient so they don't hold us back too much in sub-foiling conditions.

Righting moment is vital, first to reach takeoff speed, then to continue foiling at speed when the apparent wind moves forward. Ideally we want all our lift on the leeward side for best performance in a straight line.

It is not at all clear that the most aggressive foiling setup will be fastest across a broad range of conditions. Experimentation and competition will tell us where the balance lies.

So much for straight line sailing. In the next post we will look at control at low speeds, and speed profile through manouvres.

Disrupting

You've probably noticed that suddenly 'drones' seem to be everywhere.
Multi rotor filming platforms, potential parcel delivery systems, recreational FPV (First Person View) quad-copters... Unmanned Aircraft Systems have exploded into the public consciousness.

Seemingly every day a new, creative application is dreamed up to either do at a much lower cost what only manned aircraft could do before, or to make possible things that before were simply not achievable.

This is a result of the convergence of several technologies that have matured sufficiently to be broadly accessible.
Compact light weight processors, reliable very energy dense rechargeable batteries, advanced user interfaces (including smartphone touchscreens), small solid-state sensors (gyroscope analogues), GPS, 3D printing... All now available to the average geek.
Perhaps as importantly, the internet has enabled rapid sharing of information. Open source software (from autopilots to photogrammetry), and online forums, allow everyone to immediately appraise the state-of-the-art, and build on it, adding a contribution in the process.

At a small scale, the effective power of rotary wing airframes makes them practical and versatile. For heavier payloads, and longer-distance missions (or prolonged loiter requirements), fixed wing solutions are superior.

In all cases we are talking about flying objects with considerable energy that can potentially cause problems if they fail.
Irresponsible use can bring them into contact with manned aircraft. Mechanical failure or loss of control can cause property damage or even injury to those on the ground.

As with any new industry, regulation has to strike a balance between staying out of the way of innovation, and guarding against damage caused by unsound practices.

Responsible stakeholders can play an important role in guiding the process of developing regulation.
Operators and insurance underwriters have 'skin in the game'. Voluntary professional standards are a great way to reassure the end customer that she is dealing with a well set up and responsibly run provider.

It is great to see an Australian initiative take the lead in formulating such standards for unmanned aviation.
UAS International held a launch event yesterday.
Carbonix was there, displaying a complete airframe in support of going the extra distance to assure quality. Our presence staking out a claim as a responsible manufacturer, and the first in Australia to offer all-composite airframes for commercial civilian applications.

Much more to come in this exciting space...

Golden Rule

One final reflection about recent events in the A Class, before resuming normal programming.
Future posts will focus on hopefully interesting technical commentary, and updates on our projects...

Flourishing

The last couple of years gave us extraordinary advances in the capabilities of inshore racing sailboats.
Arguably the root cause is development in the America's Cup, where big foiling multihull 'daysailers' benefited from the focused study, and substantial R&D budgets, of professional teams in a high-stakes arena.

This work furthered our understanding of how to make such boats faster and safer.
It also helped popularise a kind of fast sailing that previously existed on the fringes of a sport not necessarily known by the layman as particularly dynamic.

We have seen multihulls 'go mainstream'. Preconceptions about poor maneuverability, and unsuitability for close racing were dispelled.
Once full foiling became possible, a new dimension of speed, technical challenge, and spectacle became reality.
Basic insights, tools, and technology were quickly applied to 'accessible' craft, including one-design classes, and even fast cruisers.

The top tier of the sport was rejuvenated, and the appeal of sailing broadened.
This did not detract from 'mature' disciplines (the monohull scene is still thriving. Only now there is more on offer).
Keelboats, foiling Moths, and foiling multihulls, all benefit from a broadening of the base. Lessons learned in one specialty advance the others.

Origin

Reflecting with some fellow sailors, an important realisation dawned on us:
ALL of the above flowed from the literal interpretation of a rule specifically designed to prevent foiling.
Think about it: The AC72 Rules had provisions intended to limit foil volume (and hence foil area) to a value insufficient for full foiling.
Clever designers in Emirates Team New Zealand spotted that the wording of the rule allowed a literal interpretation completely contrary to intent.
Yet once written, the rules had to be applied as worded.
Consistency dictated that the plain meaning must be upheld.
Though this gave an initial advantage to the discoverers of the 'loophole', it also opened the door for others to follow. Even to improve on the original idea.

Sports, architecture, and law, are littered with examples of 'rule cheats' that either opened the door to progress, or exposed the absurdity of outdated regulations.
Normally regulators react by permitting such solutions until rules can be properly changed, usually after a season or cycle has concluded, then everyone can start again afresh.

Some interesting examples for the curious (links to external articles):
- Due to sloppy rule drafting the class rules could be literally interpreted to read...
- Committee had exceeded its jurisdiction in issuing an interpretation that changed a Class Rule...
- The F-duct was so smart that the FIA used it in creating what's known as DRS today...
- Brawn's double diffuser in 2009...
- One of many unintended consequences of tax policy...
- Slicing part of the rocker overcomes the prohibition against hollows in the hull with an 'appendage' not as it was intended...
- The judicial is separate from the legislative precisely to objectively interpret law...
- 'Contrary to the spirit of the law', exposed as a ludicrous question...

Lesson

Rule administrators have a duty to be impartial when issuing interpretations.
They must keep intent at arm length, look at the wording with fresh eyes, and read the rule as written. They must ask themselves: "What would this mean to someone reading it with no preconceptions, coming from a different background, unburdened by the baggage of what was in the inscrutable mind of the writer?"

Saying that we should "not [be] spending our time looking for loopholes" is disingenuous.
It is doing a disservice to the Class and the sport.

Those charged with issuing interpretations have a duty to objectively apply the rules.
Attempting to enforce an arbitrary view of preferred outcome is ineffective and unfair.
Ineffective because it invariably fails to achieve the intended outcome, rather fostering elaborate workarounds that divert energy from genuine development. Unfair because it makes it impossible for participants to reliably know what will be deemed acceptable by the whim of the arbiter.

Once loopholes have been found, acknowledged, and exploited, then the discussion can begin to either tighten or get rid of defeated rules.
This is finally happening in the A Class, thanks to the persistence of those who take to heart the history and ethos of a unique and exhilarating development class.

"The golden rule is that the words of a statute must prima facie be given their ordinary meaning."
Viscount Simon, in Nokes v. Doncaster Amalgamated Collieries, [1940] A.C. 1014, at p. 1022.

Declaration of Independence

North American A Class sailors recently voted to Remove Rule 8 as a constraint during their events.

With my apologies for editing one of the most important texts in history, here is a tongue-in-cheek look at why the move was necessary and successful:

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Foiling.
That to secure these rights, Technical Committees are instituted among Men, deriving their just powers from the consent of the Sailors.
That whenever any Form of Measures Guidelines becomes destructive of these ends, it is the Right of the People to alter or to abolish it. 
When a long train of abuses and usurpations, evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Government, and to provide new Guards for their Boatspeed and Stability.
Such has been the patient sufferance of these A Class Sailors; and such is now the necessity which constrains them to alter their former Systems of Measurement.

Hyperbole aside, this initiative could finally return certainty to a Class that has experienced some turbulent times, but is nonetheless popular and loved.
It will hopefully lead to other Nations following suit, eventually bringing about an official change to the International Rule.

I have previously stated that the current Rule, if interpreted consistently, though not perfect, allowed sufficient freedom to keep developing in the historical spirit of the A Class. Such development being key to remaining relevant as the foremost big fleet development beach cat.
However, for reasons that may be genuine or self interested, a small vocal group has insisted on applying what they view as 'the spirit of the rule' as they claim was intended.
The result has been inconsistency, uncertainty, and growing anachronism, as other classes, one-designs, and now even cruising boats pursue the sensible path. While the A struggles with elaborate, inefficient and dangerous rule cheats.

A Few Examples

'AND' does not equal 'OR'.
This hardly needs explaining. Consider the following sentences taken from established jurisprudence:
- Men over 30 and single shall receive admission.
- Men over 30 or single shall receive admission.
Plainly the latter entitles men under 30 to receive admission whilst the former does not.
Read Rule 8.2 and draw your own conclusion.

'All positions' cannot include what happens before or after racing ('racing' is defined by ISAF).
On the beach, we remove our straight, curved, or bent foils, and rest them on the trampoline. Often we place them so they overhang the side of the boat.
Similarly, we lower our sail right past the lower limit band.
For that matter, we might lower the mast by pivoting it forward so it grossly exceeds maximum overall length.
All such actions would not be permitted during racing, the only time when our equipment must be rule compliant.
In order to indicate limits to permitted positions, contrasting bands are painted on.
Though equipment can travel past such bands (a subset of 'all positions'), our honour (plus the possibility of being seen) keeps us compliant during racing.
This is accepted even for 'newfangled' L and T dagger rudders, where full retraction breaches Rule 3.
Standard practice applies throughout: If you don't do it during a race, it is fine.
Should foils somehow be held to a different standard because, in the minds of some, arbitrarily perceived intent trumps consistency and an expectation of objectivity?

Interlinked appendages (such as two rudders connected by a crossbar), both reacting to forces exerted by wind and water, are accepted and common. Join the dots...

Going Forward

Enough said on the way Rule 8 was stretched and tortured.
Removing it makes sense for two principal reasons.

1) It is the only 'non-dimensional' rule in a Class that is otherwise governed by 'boxes'.
Limiting length, beam, mass, sail area, and other key dimensions keeps absolute performance close among different designs, but allows experimentation with novel configurations. All within clear limits.

2) Freeing up how foils may be mounted makes it much cheaper and easier to upgrade an older boat to close the gap with newer ones.

Reiterating Our Conclusion

I believe manufacturers should cater to market demand rather than agitate for rule changes.
There should be an expectation of consistency in the application of a published and valid rule, so that all who invest time and money in our great sport can do so on a level playing field.
When things become plainly untenable, then we should support change.

The message is a positive one: Get out there and develop. Things are looking up.
To abuse another great historical statement:
This is the end of the beginning!

Examples of equipment that can potentially exceed measurement limits in some positions,
but is accepted provided the range of motion is limited during racing.
The most common (not shown) being mast 'black' bands.
Singling out certain types of foil is inconsistent.

Diagram taken from current Measurers Guidelines.
Clearly the measurement 5.79m has no basis anywhere in the Class Rules.
This is one of several guideline that effectively alters the Rules, adding to them without due process. A pattern?

Also from the official Guidelines. 

I superimposed the green foil which is identical to the blue ones in the Guidelines, but shown at an intermediate position not included in measurement.

Foils that exceed rule limits between measurement points are specifically permitted, as long as the breach does not happen during racing.

In this case the appendage would presumably not be retractable during a race.

So to exclude other types of movable but not retractable appendages is untenable.
An L foil inserted from below is obviously not retractable. Therefore it should not be bound by Rule 8.2.
Removing Rule 8 eliminates these niceties. Life will be simpler as a result.

Integration

Intense times as we are gearing up to take on more challenges.

We have completed another recruiting phase. Our extraordinary team has grown even stronger.
If you have missed out on the latest openings, get in touch anyway and we will keep your details on file for future opportunities.

The next step is integrating our various operations under one brand.

A new website is under construction to reflect recent growth and changes.
As always, your support and passion are vital in keeping us going.

Below is an image of our new home, now close to fully fitted out, and re-branded.

Growing

We now have an opening for a composite fabricator/shipwright.

Our workload is growing so we would like to take on another team member.
Projects include UAV airframes, customer parts, RC yachts, and our A Class catamaran.
A good mix of one-off prototypes for R&D, and production items.

If you possess skills in carbon fiber pre-peg construction, with an aerospace or marine background, and would like to join a growing team working on interesting products, contact us by email: info@carbonicboats.com

Paradox 2015

First Public Introduction of our All New A Class Catamaran

Concept

-          Speed, stability, easy to tune for different conditions, value, elegant engineering.

-          Benefiting from three years of structured testing, data collection and validation.

-          Developed in close collaboration with Glenn Ashby.

-          Built in Australia to aerospace standards.

Hull Shape

-          High volume combined with narrow waterline beam through U shaped sections.

-          Flat bottoms for maximum planing lift and minimum dynamic wetted area.

-          Rocker shaped for responsive trimming: Easy transition from bow-down (lowriding) to bow-up (step back/takeoff).

-          Bows have generous volume underneath and peaked low-freeboard tops for wave piercing and water shedding.

Platform

-          Low windage and high stiffness.

-          High modulus beams, Nomex cored hulls.

-          Integrated construction, sealed low-stretch trampoline, streamlined rear beam.

-          Future-proof foil case design, able to take any shape foil. Go from Z to L with no mods.

Foils

-          Optimised Z foils with variable section (camber changes along the span).

-          Full use of permitted lifting span.

-          Precise rake adjustment through worm-gear, as used by proven foiling classes.

-          Good foil support (no slop, no jamming) with precise toe-in through rotating bearings.
-          Optional L/V foils, plug and play. 

Steering

-          All new: A leap forward from the existing dagger/cassette concept that we pioneered and has since been widely adopted.

-          The new system allows much better refinement of rudder planform as well as easy rake adjustment on the water and greater safety.

-          Superior grip at low speed, low drag and precise control when foiling.

Availability

-          Customer deliveries expected to start in August 2015.

-          Ongoing deliveries after September including containers to the Americas and Europe.

-          Contact us now to lock in a hull number with a conditional holding deposit.

Contact

Email: info@carbonicboats.com

Phone: +61 412 127 388

Opportunity

An opening exists for a junior laminantor and fabricator at Carbonicboats.

The position includes loading prepreg into moulds, assembly tasks, bonding, finishing and general hands-on work under supervision.

Some experience is preferable, but the right attitude is vital.

The successful applicant will be passionate about quality and technology, reliable, ethical, and committed.

A number of projects are in the pipeline and opportunities exist for progression in a growing company with a singular vision.

Email applications to info@carbonicboats.com

Applications will close on Friday 20/02/2015

Farewell 2014

Some images looking back on a year of regrouping, transition and growth:

Production L rudders, proven at the A Class Catamaran Worlds 

Mould for experimental T rudder elevator with junction bulb.

 Part of extensive R&D work on appendages

Rudder gudgeon assembly with 'between races' rake adjustment

Experimental gudgeons with 'on the fly' rake adjustment
via tiller extension twist-grip

Billet rudder cassette. Our concept of 'dagger' rudders with offset axis has been widely adopted

First A Class 'V' foil concept. 'Inspiration' for current Z foils

Retrofit foil case kit with rotating bearings

Moth bow swivel fitting developed with Scott Babbage. Production version available here: http://www.sailingbits.com/class-specific/moth-bow-mechanism/

Moth bellcrank developed with Scott Babbage. 
Production version available here: http://www.sailingbits.com/class-specific/moth/moth-adjustable-bellcrank/

Bolts with streamlined heads. Used on UAVs and various sailboat classes

Experimental Finn mast chocks for NB Sailsports

18' Skiff rig spanners for Allmarine. Available here:
http://www.allmarine.com.au/shop/boat-specific-products/18-foot-skiffs/all-marine-rig-spanner/

Tasar fittings for NB Sailsports.
Available here: http://www.nbsailsports.com.au/store/product-info.php?pid1365.html

Fairleads

Trophies for A Class Catamaran Nationals

Choices

We have received many questions regarding the differences between ‘active’ and ‘passive’ foil systems for full foiling.
So here is a look at the principles with respect to performance.

Active

An active system consists of a foil with variable camber or variable angle of incidence controlled by a sensor that measures heave position (ride height).
The input can be via a mechanical device such as a wand/float or an electronic sensor.

Usually the main lifting foil is fully submerged. In order to minimise the total lift necessary, the submerged foil should be angled to provide both vertical and horizontal force components.
The vertical component holds the boat up and the horizontal component resists leeway.
Moths achieve this vectoring by heeling to windward.
By vectoring the lift from the submerged/active span, the vertical struts are not significantly loaded so surface-piercing effects are minimised.

It is interesting to note that where active T foils have been tried on catamarans the results have been less than promising because vectoring was difficult to achieve. Sideforce was provided by the surface piercing vertical struts. These got smaller with increasing ride height. Also their pressure field interfered with the main lifting foil degrading efficiency.

With twin Ts it may be possible to set the hulls up for differential ride height (set the neutral point on the respective sensors differently for windward and leeward foil) thereby encouraging the platform to stabilise at a heeled ride height. However the downside is that the windward foil will have a long span of submerged strut (since the foils are far away from the centreline, the difference in immersion from upright to heeled is large).

One concept we tested, designed by Dave Lister, showed promise by combining active heave control and lift vectoring via angled fully submerged lifting spans for minimum wetted area.

On an active control setup, lifting foil area does not change with heave. The submerged portions of the vertical struts get shorter but this has little effect on total lift. Instead lift is controlled by changing the lift coefficient of the main foil, either through altering angle of attack or, most effectively, through adding camber by deflecting a flap.

A flap alters camber and changes the angle between chord line (light blue)
and oncoming flow (dark blue)

Passive

This solution comes in different forms. Variations on V configurations rely on a decrease in immersed foil area with heave.
Other solutions such as the acute L/V rely on a coupling between heave and leeway such that increasing leeway reduces the effective angle of attack of the main lifting surface.
Where leeway values are very small, an L/V foil can also use a reduction in lifting area (inboard tip breaching the surface) as a last-resort means of limiting ride height.

Tradeoffs

Mechanically it can be argued that the overall complexity is similar: Active systems have swivels, pushrods and bellcranks that require significant refinement and must be looked after correctly. Passive foils require hull and deck bearings and means of adjusting depth and rake.
So ultimately the cost differences are minimal.
Active foils need some form of articulation built in (a shaft or flap) so they are more complex to produce. But they tend to be made from straight segments whereas passive foils tend to have curved spans so their tooling is more expensive.
Again, on balance cost is not a deciding factor.

Active foils with mechanical sensors tend to be at a disadvantage in light winds and marginal foiling conditions because there is a drag penalty associated with the control system.
In non-foiling conditions the sensors can be disconnected and retracted. But then no lift is available so any puffs would see the passive boat move ahead in foil-assisted mode.
Arguably the active setup is also heavier depending on where the sensors are located and how they connect to the foils.

So on a small cat the passive foil would have the competitive edge in very light winds.
The exact crossover remains a subject of investigation and will be found to depend on variables such as displacement/length ratio, sail area/wetted area ratio and the exact design of the foils...

Once foiling the active system requires less deliberate correction by the skipper.
This favours the less advanced sailor but probably makes little difference to the nuanced expert who is constantly making adjustments by muscle memory.

The crucial difference is this: An active foil can be smaller for a given takeoff speed because lift coefficient can be maximized when needed and dialed out when not required.
You can have an aggressively cambered foil on takeoff and a flat low-drag one at high speeds.

This is not impossible with passive foils. For example, the section used in the upper portion can have more camber than the one used near the tips.
But the compromise is more critical.
It is more difficult to have early takeoff and low drag at high speeds.

If the rules are tested and the A Class decides that active controls are not desirable, then passive systems will evolve rapidly and the problems will be solved.
Hopefully the decision will be an informed one based on a good understanding of the options rather than on prejudice and fear of the unknown.
In either eventuality the development process will continue to be fascinating.

Graph from UNSW Team 1: Sam Paterson, David Kirkby, Byrce Edmonds, 

Ashley Thornton, Felicity Kelleher, Nick Tenison, Syafiq Nazarudin 

And Team 2: Jarred Grimmond, Nay Myo Lwin, Stephen Narunsky,
Julia Shields, Tyler Steer, Hu Su