Rules for the Open 20 Class:
1 October 2011

The OPEN 20 is Box Rule Set designed to foster the development and progression of the 20 foot racing catamaran fleet by permitting manufacturers and owners to institute improvements within existing fleets and encouraging development and innovation within the parameters of the Class.

1. Intent and Objective

1.1. The intent of the OPEN 20 Class is to open the platform and sail plan to improvements by providing maximum and minimum parameters for the class to develop within. It is specifically the intent of the class to permit any modifications that are not specifically prohibited by these rules within the spirit of the class.
1.2. The OPEN 20 Class is open to any two-hulled sailing boat with essentially duplicate or mirror image hulls, fixed in parallel or near parallel positions.

2. Overall Length
2.1. Any new OPEN 20 build shall comply with a 20 foot overall length requirement. The length shall be measured between perpendiculars to the extremities of the hulls with the catamaran in her normal trim. The measurement shall be taken parallel to the centerline of the craft and shall exclude rudder hangings.

2.1 “Grandfather”—Any legacy “20 ft.” catamaran, defined as a catamaran >=19 feet and <=20’6”, built on or before the adoption of this Class shall be permitted in the OPEN 20 Class provided that it otherwise meets the Class requirements.

3. The sail plan shall consist of 1 mainsail, 1 jib and 1 spinnaker that shall be carried aboard.
3.1 Sails may be manufactured by any sail maker and will be measured in accordance with the F16 sail measurement guidelines

3.2 A measurer recognized by the OPEN 20 class shall certify all sails.

3.3 Each sail maker shall present a certification of the sail’s measurements.

3.4 No sail shall be replaced during a regatta, except when a sail has been lost or damaged, then only with permission of the Race Committee.

3.5 Total sail area of the 3 sails and mast shall not be more than 50 sq. meters (538 sq. ft.). The jib is required to be at least 9.5% the area of the main sail. The total sail area can be no greater than 50 sq/meter.

3.6 Once measured and certified, the sq. foot/meter measurement of each sail shall be indelibly marked near the tack point of the sail for future verification.

4. Mast—The mast may be built from any materials and may be any length provided that the total sail area limit is not exceeded.

5. The beam of the catamaran shall not exceed 8 feet 6 inches.

6. The minimum weight of the boat in full trim shall not be less than 350 lbs.

7. Crew Sailing Weight: Minimum crew sailing weight is 325lbs. If you require corrector weights to meet the 325 lbs minimum they will be attached to the main beam or placed in the hulls evenly distributed side to side. They may not be moved during the racing.

8. Team size: 2

9. Rule Development-As a developing class, registered member suggestions and discussions will drive change.
9.1. After the first year re-address rules 9.2. Thereafter, every 3 years re-address rules

After much discussion, the Open 20 working group has agreed upon a set of rules to govern the new Open 20 class. Below is the rule set to govern the first Open 20 event scheduled for 8-9 October 2011 at Key Sailing in Pensacola, Fl. "2011 Nacra 20 (and then some) North American Championships" This rule set is designed to be reconsidered in 1 year.

The intent of the rule set is spelled out in section 1.1. It is not intended to exclude anyone from the class but to open the options available to you for new sails, replacement parts, etc. The "etc." is up to you. It is our hope that this class will encourage people to renovate the existing fleet to compete with each other and to remain competitive with the rest of the DPN fleet. Eventually, we would like to see new platforms being built to grow the class and become a thriving Open 20 class.

What changed from the F20na ruleset?
I hope you plan on sticking with this one. It doesn't foster alot of trust when the rules and name get changed so quickly.

So

No restrictions on materials.

No restrictions on boards of any type.

No restrictions on rig except that you HAVE to have a jib it appears (sorry M20 owners - guess you could always build a wing)

No problems with extending the rudder appendage off the stern like they did in the C-cats.

No restrictions on trapping racks or wings (not the wing sails)

I mean, this is pretty much an arms war if you ask me.

cool I can put 8.5' beams on my F20c and have a smaller main cut and I measure in?

This should be renamed the "Retarded 20 Rule Set", even kindergarden kids can exhibit more progressive logic than this rule shows

Why would you do that? What race would be worth it to you to bastardize your Cadillac ride?

To the organizers of this rule...
What is your thinking about a min boat weight of 350? How do you think you can get decent racing when the founder boats are 50 + lbs heavier?

If weight doesn't matter... why the min crew weight?

Good question
Originally I proposed a 320lbs boat. Why? Because there is no reason in this day and age that a 20 ft boat should have to weigh 400 lbs. I picked 320 because it's 100lbs lighter than my old 6.0 I sailed. Everyone knows how painful it is to move boats around the beach and truthfully this weight issue keeps people from sailing. Just ask the F16 guys how much they miss their heavy boats. There was so much criticism of this detail that we compromised at 350. Ideal? Not at all. Keep in mind the rule set is designed to get the class started and the interested parties have the chance to ammend/change the rules in a year.

Crew weight? I recommended no limit. Look at the original set. Again, there was much weeping and gnashing of teeth over this so we included the minimal weight. Ideal? No. I don't want to pull out scales but if some smart butt wants to race his 20 with his 1 yr old daughter and call it 2-up then this rule calls them on it. You know how these boats perform in even 10 kts of wind they like some weight on the wire.

I hope we can get past the rhetoric and work through the real questions that matter to the class. I am fully aware there are plenty of people that have strong emotional opinions on this issue but that doesn't mean we don't evolve the class. It's been discussed for years and shot down because no one has been up for the task. Our small consortium is trying to make some happen. If sailors don't want to support then that is their prerogative but I ask that if they don't want to participate please don't try and derail our efforts. Please be a part of the discussion. We all love saili g and want to see our sport thrive. We just have different opinions how that should happen.

Thank you for your questions. I'm very willing to discuss every detail in the rule set.

My advice... It's about the events! If the events are worth your while to win.... people will tweak their boats... build new ones or train to improve their performance. The more people engaged in these games... the more fun had by all.

I agree. We will have a slate of races for the 2012 season no later than Jan 10.

Capt C,
I see you have started something here and I'm guessing the next step would be some sort of class orginization with a mission statement, bylaws and elections? You have my attention way out here in Hawaii. Waiting on the fence under my coconut tree,
Dan'o

Looks like David and Mike K ON THE n carbon 20 and JC on the Marstrom were pretty evenly matched ,--perhaps this is the basis for the F 20 class ?

Carl

yes good idea. But which M20 will be the class legal one?

Boys,

It's a 8.5 beam class. No F20C of M20s. It is what it is.

The Nacra F20na fits nicely into the class.

So what number is this class racing at?

You had to ask . . .



59.3

So if its currently the same rating as the Nacra 20 I guess the Nacra 20 and Open 20 are still racing roughly equal despite sail updates? Is there any other modifications other than sails being used currently?

Picture of a new F20na in USA

What modifications are being done to the Inter/NACRA 20 sails for the Open 20 class.. Are they bigger than what came stock?



Is that going to be rated at 59.3 too if the skipper enters it in the Open 20 Class?

It's rating at 59.3(provisional) and as we get data we will continue to update. The sails are 50sqm you can divide them up per the rules but the latest sails are following the development lines of the F18s since that is where the biggest changes have been in the last 10 years. I'm aware of 3 sailmakers building newer design sails. Schurr, Glaser and Performance.

The F20na fits in the class. Hopefully we'll get a chance to see how she performs.

There have been a few mods to existing N20s, different mast/booms/spin poles and most notably the sails.

So what I am reading and using the Inter/NACRA 20 as an example is that you can go from 45.15 meters square to 50 meters square of sail area; about a 10% increase, and still maintain the orginal N20 59.3 DP-N rating, albeit it being provisional?

Most of the specs I look at online show the N20 sail area to be 527sq ft or 48.9 sq meters.

What is an F20na?

F20na
Beam 8' 6"
carbon mast 31'
Hulls F20C

F20na pictures

Thanks for the correction have to stop referring to it as an Inter 20

Inter 20 Specs

Specifications
Length: 6.10 m 20 ft.
Beam: 2.59 m 8&#8242; 6&#8243;
Weight: 177 kg 474 lbs.
Sail Area: 45.15 sq m 486 sq. ft

A F20c narrowed to 8'6"?

we used the F16 measurement convention.
The EP sails measured in at 49.06 sq. meters
the new Performance sails measured 46.489

The F20na also reduced the overall sail area compared to the F20c.

Did you get a confirmation from Skip Elliott the M-sq of his sails or this something you came up with?

If you don't mind me asking, if you're going to allow for a modified Inter/NACRA 20 to sail in the Open 20 class with a 59.3 DP-N, do you guys plan to run two classes; that is a Inter/NACRA 20 class for the stock boat and an Open 20 Class for the boats that are carrying the modifications?

For the Open 20 Class you may want to reconsider your "provisional" rating.. Seems a little unfair to those that don't want to have to spend beaucoup duckets to keep up with the Joneses

We measured the sails.
If there are enough stock I20s they can always have there own class.
The provisional rating is just that. We will continue to compile data.

Howdy guys

I am going to modify my f18 into a f20 but notice your rule set is not quite the same as the schrs rating measurements found here

http://www.schrs.com/ratings.php

Is your open 20 class going to based in the US only.?

Clayton

I believe it's currently limited to the southeast.