I have followed lots of discussions on this site about various types of classes but have to confess I don't really understand what the differences are.

So what is the difference between a class boat and a fomrula boat (A class versus formula 16) and what is the definition of

Open Class
One design
Development Class

and whatever other types there are?

Gareth

Grob,

>>So what is the difference between a class boat and a fomrula boat (A class versus formula 16) and what is the definition of


Actually sometimes there is hardly any difference between a class boat and a Formula boat. The only class boat that is different are the one-design boats. To give a few examples.

A-cat class is actually a formula type of class and the the hobie tiger one-design class is nothing more than the Hobie Tiger F18 boat (Formula boat) were all the other brands of F18's are not allowed to participate. The tornado cat is a one-design class with formula characteristics. The Hobie 16 is a class which is a SMOD (single manufacturer one-design) class without formula characteristics.


First the definitions :

>>Open Class

This can refer to two types of fleets ;

-1- a fleet were all the boat type compete against eachother using a handicap system to filter out the performacne of the boat from the capabilities of the sailors. The best sailor is expected to win here independent of what type he sails.

-2- A class were everything with respect to design is allowed and where the first over the line wins.


>>One design

All the boats in a fleet are of the same design. Sometime small allowances are made to modify the design in certain area;s or to use parts from other suppliers than the builder. Parts like sails, blocks, aftermarket rudder blades etc. Examples of these classes are the Tornado and Taipan 4.9. In case of the Tornado, the platform couls be build be different independent builders as long as they stuck to the plans on the items that were not allowed to be altered.

Than we have the SMOD, single manufacturer one-design class. Example of these are Hobie 16 class and dart 18 class and nearly all other hobie classes, Nacra has a few of these classes as well and the Swell Spitfire is one of these two. All boats in the fleet are intended to be completely equal and not a single item or part may be altered or replace by an item that is not bought at the builders. Some people call this a monopoly. Other often complain that teh difference in parts are sometime unacceptable big. Recently a complained was filled with Hobie cat because their jibs could swinf in surface area by an unacceptable amount. Often the class rules don't specify dimensions but only state that anything purchased through the single builder is compliant. This type of class is rapidly loosing ground in most parts of the world. The Hobie tiger is different story as the changes in this design follow the F18 formula class rather than SMOD lines; although teh rule do say that everything must come from Hobie inc.


>>Development Class

This name is often used for classes that have very limited number of rules. Today these are only found in the old ISAF classes of A,B,C and D classes which only used to rule on length, overall sailarea and width. Within this set of three limits anything was/is allowed and therefor these classes saw alot of development like solid wingsails and continued reduction of overall wieght.

Today only the C-class survives in this mode. However some classes do still claim this title even when they both have become far more formula classes rather than development classes.

To give an example, The A-cat now also specifies a minimum weight and disallows hydrofoils. The F18HT class also disallows the use of jibs by rule and limits mastlength for eaxmple. And rumour has it that they will disallow solid wingsail by rule.

As a rule of thumb all classes are moving towards a type of Formula framework where some classes have less restrictions than others but all are more limited than the old A, B, C, and D classes. These classes are nowadays only used in their old form in speedtrails and the Old little Americas Cup.


>>Formula classes :

Here a framework of performance limiting rules is created to force every conceivable design into an equal performance as its peers made by other designers and builders. As long as your design satisfice a set number of limits your are considered compliant and may enter the given race an race teh others on first in wins. You may use parts and items for all builders and suppliers as long as they measure in. This frame work allows the most freedom to both designer and participant while still allowing the individual designs to race against eachother fairly on a first in wins basis. Often refinements in saildesign and other area's allow for a gentle but continious improvement of overall performance. Therefor some development is found in these classes. Especially because it is very easy to compare new idea's against older ones. Often the development is slow enough to allow designs to stay competitive for several years. The best know class of this format is the Formula 18 class.


On the actual comparison between A-cat and F16 class.

The differences are rather small. In handicap they are at max 5 % apart in performance. When using a spi the differences are neglectable around the course. The a-cat is a formula class format with very few limits, has less than 10 limits I think. The F16 class has about 15 limits on the design itself.

The A-cat class format is more open and will allow specilized combo's of masts and sails for the expect conditions of a given event while the F16 format is more restricted in this area and forces the use of the same combo which may be made by different builders and suppliers.

The A-cat format is more concerned with getting the faster singlehander while the F16 format is more concerned in enforce equal performance between designs which may slowly improof as a whole over a time span of say 5 years. At which time most racers have bought new platforms already. So trather the whole fleet advance in performances than individual designs. The development is much more controlled and slowed done because it needs to be done through small refinements which often can easily be implemented on older designs too. Like selftakers, new sailcuts etc.

Neither class forces you to but parts from a monopolized supplier nor do both disallow you to set up your boat to your personal liking or do they limit your options to optimized your boat for your weight.

I hope thsi expains things

You said:
"So what is the difference between a class boat and a fomrula boat (A class versus formula 16) and what is the definition of: Open Class; One design; Development Class"

Class boat, roughly equivalent to one design:
Usually same manufacturer, (can be more than one) strict rules as to sail, hull, spars configurations, must be identical, or as identical as possible (identical=onedesign). Hobie 16, Tornado, J-boats are onedesign.

Formula boat:
Can be by many different manufacturers, the rule here is conformation to a 'formula' which defines sail area, waterline length, and overall boat weight. Within those parameters and a few more, you can do whatever you want. America's Cup boats are formula boats, as are the NACRA F18, Hobie Tiger, etc. I would call the Acat more of a formula boat than a true 'class' boat.

Open class:
Racing whatever type of boat you like, scoring is equalised by assigned handicap numbers, such as Portsmouth, PHRF, or Texel, etc.;

Development class:
Similar to formula, but with fewer rules as to boat configuration, and more open as to modification. Usually sail area and waterline length are the only restrictions. In the case of the 18 Square, for example, the class is divided by weight into categories, but the division is broad. The 18 Square is a development class boat, as are the C-cats.

Hope this is a bit more clear,
sea ya
tami