UIM · Hull and handling
Legal in every class. The envelope differs by DIVISION, not by class.
The Ski and Runabout envelopes are genuinely different numbers (52 vs 63.5 mm channel, 50 vs 63.5 mm drop, 126/153 vs 92 cm length). A sponson listing needs a per-division answer, not one UIM figure. Both differ again from IJSBA's 91.45 cm / 63.5 mm.
24 classes, grouped by the answer rather than listed one by one, because an answer that holds for a class usually holds for every class that borrows its rules. 8 of them publish no component rules of their own and are marked below; for those, the link to the parent class is read from the categories table rather than stated in the rulebook.
Governed by the parent class 8 classes
No component rules are published for this class and no single parent class is named, so this part cannot be answered for it. That is an absence in the rulebook, not a permission.
Legal, within limits 3 classes
TWO REAR SPONSONS required. Max 92 cm each side, 100 mm protrusion, 63.5 mm channel, 63.5 mm below the hull intersection, minimum 6 mm thick.
Legal, within limits 3 classes
Same as GP4. · 501.02.02.04
Legal, within limits 3 classes
Max 2 sets. Max 153 cm each, 210 cm total. · 501.04.02.02
Legal, within limits 2 classes
Max 2 per side. Max 126 cm each, 153 cm total with two sets. Max 100 mm lateral protrusion, 52 mm vertical channel, 50 mm below the hull side/bottom intersection, 50 mm below the lower bond flange. Minimum 6 mm thick if aftermarket.
Legal, within limits 2 classes
Identical, plus the bond-flange protrusion clause. · 502.04.02-02
Legal, within limits 1 class
Identical. · 502.02.02-04
Legal, within limits 1 class
Identical via inheritance.
Legal, within limits 1 class
Max 153 cm each, 210 cm total, via the Kawasaki SXR1500 derogation. · 501.03.02
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 UIM class · where the rulebooks differ · signed checks on parts the shop sells.
Hull and handling · two and four stroke · legal outright in 16 of 24