Freestyle competition legal hull dimensions

Dalton

Dalton

Location
Wisconsin
I have some questions about the rules regarding hull dimensions.
Freestyle ONLY: The top deck of freestyle craft may be modified or aftermarket, providing the following: The
top deck must resemble the original top deck of the homologated watercraft; the length of the top deck must be no less than 165.1 mm (6.5 inches) shorter than the original OEM top deck and the width of top deck must be within 50.8 mm (2.0 in) of the original component; the craft must function as originally intended. The hull may be no smaller than the minimum measurements of the top deck. These restrictions also apply to the minimum length of the hull. The front bumper may add no more than 31.75 mm (1.25 in) to the overall length of the Top Deck for the purposes of meeting the minimum measurements. Fuel fillers may be relocated internally.

Freestyle, Ski Type, ONLY: The top deck of freestyle craft may be modified or aftermarket, providing the following: The top deck must resemble the generic look of existing homologated watercraft with the following dimensions: Minimum Length of 193 cm (76 in), Minimum Width of 68.5 cm (27 in), Minimum Height of 53.3 cm (21 in).
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Link to rulebook: http://www.ijsba.com/pdfs/rulebook/rulebook_2014_all.pdf
I understand the minimum length and width requirements. About the height requirement, I'm assuming that is including the hood?

What is meant when they state "The hull may be no smaller than the minimum measurements of the top deck"? I see many aftermarket hulls with top decks that extend far past the end of the bottom deck.

They state "the length of the top deck must be no less than 165.1 mm (6.5 inches) shorter than the original OEM top deck" given a superjet is 88.2 inches and they state a minimum length of 76 inches does this then mean that a hull must be between 76" and 81.7"?

The rules seem to imply that aftermarket hulls are based off an OEM hull. What about a hull made from the ground up? Is that even legal under these rules?

I am also unclear of what the regulations are on bond rail dimensions if there are any.
 
Dalton

Dalton

Location
Wisconsin
So I read on here that a superfreak for example is 76 inches. Maybe I'm wrong but those are superjet based and consequently illegal for competition use?
 
Tyrant1919

Tyrant1919

Site Supporter
Location
Washington, DC
From what I heard, freestyle rules are enforced by the freestyle competitors themselves. Someone may want to chime in. All of the freestyle riders inspect each others hulls. If a rider suspects somebody of breaking the rules, they can challenge that they are breaking X rule. I'm not sure if anything is enforced really except for displacement. There may be some gentleman's agreement amongst riders that just about anything goes. Take this with a grain of salt, this is my take on how it may or may not go down.
 
Dalton

Dalton

Location
Wisconsin
@Tyrant1919 I would believe it after having read the nonsense in the rulebook. If it's true that it's basically at the competitors discretion, how can any hull builder confidently build a hull and simply hope it doesn't upset anyone?

I read something from a couple years back claiming those old stunt hulls weren't allowed in competition because they were more than 2 inches wider than a superjet and therefor illegal. Anyone know anything about that?
 
madscientist

madscientist

chilling with these guys.
Location
good old p'cola
SPECIAL PRODUCTION HOMOLOGATION
An OEM Manufacturer in good standing may homologate less than 100 identically produced units that will be eligible only
for a controlled Special Production Stock Class* and the Modified/GP classes. Only units approved by the IJSBA are
eligible to be homologated in the Special Production or GP classes.
For a Manufacturer to produce less than 100 identically manufactured units of a model and qualify for current-year IJSBA
and- IJSBA affiliate sanctioned competition the manufacturer must adhere to the following criteria for all models produced
in quantities below 100:
1) The manufacturer must produce a minimum of 25 identically manufactured units of a model. Should the
manufacturer sell, or dispose of all units before July 1st then the manufacturer must produce and additional 25 units,
identical to the initial 25, and have those units available by September 2nd.
2) The manufacturer shall declare, in the initial application for homologation, that the model will have production
numbers less than 100.
3) The manufacturer shall inform and update the IJSBA as to the status, location, and/or purchaser of each unit
produced within 15 days of the units being released for distribution and shall update the IJSBA with this information
for 180 days or through the end of the calendar year, whichever is greater..
4) The manufacturer must allow the IJSBA, upon request, to broker the sale of up to seven of the total model units
produced in order to ensure distribution to IJSBA competition members.
5) The IJSBA may place restrictions on the model and withhold or withdraw the homologation of any component or
watercraft for reasons deemed to be in the best interest of the sport.
6) If the unit is not available for sale or not legal for sale in a region then that affiliate may chose not to offer the Special
Production Class.
7) The manufacturer shall transport an IJSBA official to inspect the assembly line of the unit according to the terms
listed in the homologation application.
8) Failure to comply with all requirements in this section shall result in the immediate suspension of the unit in
sanctioned competition.
The manufacturer must provide the IJSBA with a current service manual, parts catalog, owners manual and additional
technical information for each model considered for homologation.
The manufacturer must provide the IJSBA, upon request, a production model watercraft and separate components for
examination and testing for each model being considered for homologation. Items will be returned after completion of
examination and testing.
Mid-year production changes to a homologated model must be approved by the IJSBA. Samples of new components,
copies of related service bulletins and customer notification letters must be submitted before approval will be granted.
Changes and updates on all affected units must be made available at no cost to the customer, parts and labor included.
* If Lites Classes are offered then the competition organizer may merge the non-Lites Stock Classes with the Special
 
Dalton

Dalton

Location
Wisconsin
Alright so tech referred my inquiry to Scott at the IJSBA. Here is his response regarding the confusion we had over the rules I quoted and my question on dimensions.

So, you can see the dimensions allowances there. Here is how this works. You must have an OEM engine, or cranckcases based off of an OEM engine (Rule 9.3). This engine will determine what the OEM basis is for your measurements. So, if you are using a Yamaha based engine then you would be using a Yamaha Superjet. A Superjet is 88.2 inches in length. With the formula above, 81.7 inches is the minimum length that your Superjet based Freestyle Ski could be.
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This is essentially what I initially thought the rules meant. I'm still unclear on how hulls not meeting these requirements are competing. Maybe I'm missing something.

Homologation, from the information I got from Scott, seems to be meant for OEM manufacturers making complete skis, engine and hull, rather than aftermarket hull builders.

Edit: Scott just got back to me and confirmed that any ski with a yamaha based engine like a team xscream DVX is considered a modified superjet. Also hull builders are not OEM so they would not apply for homologation.
 
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V

Vortex

Location
Southeast
If you were running a yamaha engine in a small hull like the micro, could you claim it is based off the fx1? That would put the micro close to the 78" limit (originally 84") with the hull extension. Its way too wide I imagine?
 
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