IJSBA · Hull and handling

Aftermarket sponsons, IJSBA

Legal in every class except Vintage Ski Limited. Count and drop are the class discriminators.

This page is IJSBA only, and the bodies do not agree. The same part under IHRA and UIM. Which one applies to you is decided by whoever sanctions the race you enter.

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This is one body's answer, not the sport's. You are bound by whichever body sanctions the event you enter. If you race more than one series, build to the stricter answer. The differences are set out in the rulebook comparison.

Universal: max 91.45cm (36.00 in) each, 100.00mm (3.94 in) lateral protrusion, 63.5mm (2.50 in) vertical channel, minimum 6mm (0.24 in) thickness if aftermarket, radiused leading edges, never attached to a planing surface.

Where it stands, class by class

20 classes, grouped where the same rule gives the same answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules.

What each answer below means

Not legal

This comes off. The rules refuse it in this class.

Legal, with conditions

Keep it, but measure it: the rules permit this part only inside stated limits.

Not legal 1 class

NO AFTERMARKET SPONSONS ARE PERMITTED. OEM sponsons may be removed. · VSKL.2.3

• Vintage Ski Limited

Legal, with conditions 7 classes

Max TWO. Max 63.5mm drop.

• Vintage SC · VSC
• Vintage X2 · VX2
• Runabout Superstock · RSS
• Freestyle · FREST
• Ski Grand Prix · SKGP
• Sport GP · SPGP
• Runabout Open / GP · ROP

Legal, with conditions 6 classes

Max TWO. Max 38.00mm drop.

• Runabout Rec Lites · RRL
• Four Stroke Ski Lites · FSKL
• Runabout Naturally Aspirated · RNA
• Runabout Stock · RAS
• Ski Lites · SKL
• Ski Superstock · SKSS

Legal, with conditions 1 class

Up to FOUR. Max 38.00mm drop.

• Fixed Steering Ski Stock · FSSK

Legal, with conditions 1 class

Up to FOUR sponsons. Max 38.00mm below the hull side/bottom intersection.

• Ski Stock · SSK

Legal, with conditions 1 class

Up to FOUR. Single- or two-sponson configuration per side limited to 1,524mm.

• Sport Spec · section headings, no numbered rules

Legal, with conditions 1 class

Max TWO, 63.5mm drop per SKM.2.4, BUT the class also says Kawasaki hulls follow Ski Stock rules and Yamaha hulls follow Four Stroke Ski Lites rules. Unresolved conflict.

• Ski Modified · SKM

Legal, with conditions 1 class

Max TWO. Max 63.5mm drop - increased from Stock.

• Runabout Limited · RAL

Legal, with conditions 1 class

Up to FOUR: two traditional bladed plus two Tubbie-type convex appendages. Max 63.5mm drop.

• Vintage Ski · VSK

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Aftermarket sponsons: if the rule your class applies reads differently to you, or the rulebook has changed since this was read, ask. We answer with the section we read it from, or that we have not read it. Ask a rules question.

Every IJSBA class · where the rulebooks differ · checks on parts the shop sells · how this site reads a rulebook.