Dario's Lab

A Cat Rule – Is It Broken?

Many have asked me to comment on proposed changes to the A Class Catamaran Rule.
Questions fall in two areas: is a change necessary, and what should the revised restrictions be?My position is that, as a manufacturer, our task is to work within the rules, not to influence them.
Therefore CarbonicBoats will comment publicly when asked but will not favour either position or undertake any lobbying.

Generally, it should be noted that rule restrictions aimed at forcing a particular outcome (or at closing off a specific design space) invariably fail to achieve the initial intent if sufficient performance gains lie in that direction.

Like water pushing against a poorly finished dam, the forces of competition will ensure that designers and sailors find a way around, over, under, or through the obstacles imposed by specific rules.
The wording of a rule cannot cover every grain of the required ‘barrier’ in sufficiently fine detail (without effectively creating a one-design).

This is not a matter of refining the wording. Instead it is inherent in the nature of any rule framework. In fields as diverse as motor racing and tax law, the common fundamental problem is that rule writers cannot know the future.

When a rule is formulated, the experts involved consider developments that can be glimpsed on the horizon at that time. They cannot know what new permutations lie further into the future as a result of new technologies, new ideas, new combinations of concepts, new interpretations and new discoveries.

Prescriptive rules are always vulnerable, through their specific wording, to interpretations that satisfy their letter but not their intent. Such interpretations may or may not be conceivable when the rule is being written. They may be dismissed at time of writing but might suddenly become attractive to designers when new technologies appear.

At worst the result is complexity and expense to achieve an otherwise simple goal.
But at best this evolutionary process gives rise to new, superior solutions that would otherwise not have seen the light of day.
Ways around a rule need not be complex and expensive. They can be creative and innovative.
As long at the rule is applied fairly, consistently and as written.

The alternative is for rules to avoid prescriptive restrictions, instead defining general boundaries, chosen to incentivise the behaviours favoured by the rule makers.
Some of the vulnerability to exploitative interpretations remains, but ‘wholesome’ outcomes are more probable.
Of note is that every rule in the A Class except for Rule 8 defines dimensional limits. Only Rule 8 describes a particular type of feature.

The A Class is administered as an open development class with concessions to preserving popularity (number of participants) and closeness of performance. Part of the concern is a balance between innovation and preserving second-hand values.

Rather than applying a strict ‘legalistic’ system, the intent of the rule is often referred to when issuing interpretations. This may be fine as long as the context is not adversarial, and so far the outcomes have been positive. However departing from the letter of the law can only be defended under strict conditions. Doing so excessively removes certainty for all involved. Many members of the TC have high level experience in the America’s Cup and Olympics, so I trust they know this well.

In light of respect for intent, it can be argued that a higher-level approach would work equally well.
For example, instead of mandating that appendages must be inserted from above, ease of use when launching and retrieving could equally be guaranteed by saying, as proposed, that the boats must float (upright) in knee-deep water.

If the intent is to open the door to foiling without compromising practicality, then thought should also be given to narrowing the exclusion zone between the hulls under the waterline.
The exclusion zone makes sense and should stay because it guarantees that the A will remain a true catamaran (this is analogous to monohull rules mandating a contiguous water plane and no transverse hollows).

However the width of the exclusion zone impacts the aspect ratio (and hence the efficiency) of any hydrofoils, whether horizontal, angled or curved. Narrowing the exclusion zone would give designers more freedom to balance induced drag against righting moment. This would invite people to explore a more widely varied range of foil shapes, meaning more experimentation (potentially including prototypes with more complexity) and thus more cost, at least in the short term.
But it would make it easier to foil efficiently and it would probably increase top speeds.

It seems to me that the debate is not whether or not the A should be a foiling class: If foiling is faster, then the Class will foil under the current rules. Evidence points to this being achieved with more complexity and less safety if a rule workaround is necessary.
The compromised foiling that will inevitably emerge may well increase the gap between club level sailors and those with more time and resources available to master the specific techniques required by rule-tortured foil solutions.

Instead the question should be whether the Class wants to maintain the current specific prescriptive restrictions or whether it wants to adopt a higher level rule that mandates a generic ‘ease of use’ goal instead, as proposed.

Carbonicboats (like other manufacturers and home builders) entered the Class knowing that restrictions existed on the design of appendages.
Our work has shown that foiling is possible within the current restrictions with some lateral, innovative thinking. We have not yet proven that full foiling is faster around the course but all indications are that it ultimately will be.

If tomorrow the rules were relaxed, we would modify our concepts accordingly.
In all likelihood the resultant updated product would be faster at a similar cost.

It is not our role as a company to favour either outcome. We must instead create the finest product within the framework in force on the day, in terms of design, ease of use and cost effectiveness.

As a designer my view is that a rule is simply part of the brief.
In the same way as cost and time constraints, rule restrictions should be seen as challenges integral to the design process.

Simply removing restrictive rules does not guarantee simplicity and cost-effectiveness. It may even increase costs and complexity as it widens the range of possible solutions.
On the other hand, defining rules at a higher level, closer to ultimate intent than to specific restrictions, usually guarantees healthier design outcomes.

This is a matter for the Class to decide.
Hopefully this post has helped to inform the reader on the implications of both sides of the argument.

What really matters is that the rules as written are applied consistently, giving everyone certainty about the design space and the freedom to innovate within it.