1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 26Get this manual

GENERAL INFORMATION
Conditions Affecting Performance
Weather
Rated hp Horsepower Loss Due to Atmosphere Conditions Summer hp Secondary Loss Due to Propeller Becoming To Large for Summer Horsepower

RPM Drop Due to Weather

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives