Junior classes
J Hydroplane/Runabout
Displacement: 13.2 c.i. or 15.9 c.i.
Permitted engines:
• OMC 13.2 c.i., 2 cylinder with 0.5″ carburator restrictor plate
• OMC 15.9 c.i., 2 cylinder with 0.5″ carburator restrictor plate
• Mercury 60-J 15.9 c.i., 2 cylinder
Straightway speed range: 35-40 mph
Minimum Age Req: 9 Years Old
AX Stock Hydroplane/Runabout
Displacement: 13.2 c.i. or 15.9 c.i.
Permitted engines:
• OMC 13.2 c.i., 2 cylinder with 0.65″ carburator restrictor plate
• OMC 15.9 c.i., 2 cylinder with no carburator restrictor plate
• Mercury 60-J 15.9 c.i., 2 cylinder
Straightway speed range: 40-45 mph
Minimum Age Req: 12 Years Old
Modified classes
200cc Modified Hydroplane/Runabout (Formula A)
Displacement: 13.2 c.i.
Permitted engines:
• OMC 13.2 c.i., 2 cylinder
Straightway speed range: 55-60 mph
Minimum Age req: 14
250cc Modified Hydroplane/Runabout (A Mod)
Displacement: 15 c.i.
Permitted engines:
• Swanson Champion-American Hot Rod, 15 c.i.
• Mercury KG4H, 2 cylinder
• Mercury Mark 15, 2 cylinder
• Mercury Mark 20H, 2 cylinder
Straightway speed range: 55-60 mph
Minimum Age Req: 14
350cc Modified Hydroplane/Runabout (B Mod)
Displacement: 20 c.i.
Permitted engines:
• Swanson Champion-American Hot Rod, 20 c.i.
• Yamato Model 80, 2 cylinder
• Mercury Mark 20/25-20H, 2 cylinder
• Mercury KG7, 2 cylinder
Straightway speed range: 65-70 mph
Minimum Age Req: 16
400cc Modified Hydroplane (25 Mod)
Displacement: 22.0 & 22.1 c.i.
Permitted engines:
• Mercury 25SS racing powerhead
• Mercury 200, 22.0 c.i. powerhead, 1970 to date
• OMC 22.1 c.i. powerhead, 1970 to date
Straightway speed range: 65-70 mph
Minimum Age Req: 16
500cc Modified Hydroplane/Runabout (C Mod)
Displacement: 30 c.i.
Permitted engines:
• Mercury Mark 30H, 30 c.i. 4 cylinder
• Wizard WA25 30 c.i. 4 cylinder
• Yamato Model 102/302 24.5 c.i. 2 cylinder
Straightway speed range: 70-75 mph
Minimum Age Req: 16
750cc Modified Hydroplane/Runabout (D Mod)
Displacement: 44 c.i.
Permitted engines:
• Mercury Mark 55H c.i. 4 cylinder
Straightway speed range: 75-85 mph
Minimum Age Req: 16
850cc Modified Hydroplane/Runabout (Formula E)
Displacement: 49 c.i.
Permitted engines:
• Any motor manufactured as a service engine
• Any new motors must be reviewed by Modified
Outboard Technical Committee
• Any questions on legality of a motor please feel
free to contact us
Straightway speed range: 85-100 mph
Minimum Age Req: 18
Stock classes
A Stock Hydroplane/Runabout
Displacement: 13.2 c.i.
Permitted engines:
• OMC 13.2 c.i., 2 cylinder
• Mercury “A” motor
• Sidewinder 15S
Straightway speed range: 55-60 mph
mim=nimum Age Req: 14 Years Old
B Stock Hydroplane
Permitted motors:
• Yamato Model 80, 2 cylinder
• Yamato Model 102/302, 2 cylinder with 7/16″ carburator restrictor plate
• Sidewinder 20S (probationary)
Straightway speed range:
Minimum Age Req: 15 Year Old
B Stock Runabout
Permitted motors:
• Mercury/25SS
• Mercury/Mariner 25XS without restrictor plate
• Hot Rod 20 CID
• Yamato Model 80, 2 cylinder
• Yamato Model 102/302, 2 cylinder with 9/16″ or 1/2″ carburator restrictor plate
• Sidewinder 20S (probationary)
Straightway speed range:
Minimum Age Req: 15 years Old
C Stock Hydroplane/Runabout
Permitted motors:
• Yamato Model 102 or 302
Straightway speed range:
Minimum Age Req: 16 Years Old
D Stock Hydroplane/Runabout
Permitted motors:
• Mercury Mark 55-H
• Mercury/Mariner 44XS
• 402XS
• Bass/Tohatsu
Straightway speed range:
Minimum Age Req: 18 Years Old
