Horsepower limits on Pennsylvania lakes
A horsepower cap is set lake by lake. There is no statewide formula linking a lake's size to its horsepower limit; each lake's limit is whatever its own rule or posting says.
Where limits come from
Chapter 111 of 58 Pa. Code sets lake-specific limits, county by county. 58 Pa. Code §111.71
State parks post their own limits; DCNR publishes them in its Where to Boat table and park pages.
State parks: without DCNR's written permission, no gas engines totalling more than the posted horsepower, no gas engine on waters posted electric-only, and no PWCs unless the lake is posted open to motorboats without an hp limit. 17 Pa. Code §11.219(f).
Read the exact wording
(1) Operating a boat powered by one or more internal combustion engines totaling more than the posted maximum horsepower. (2) Operating a boat powered by an internal combustion engine in waters that are posted as being restricted to electric motor use. (3) Operating personal watercraft unless the body of water is posted as being open to motorboats without a limit on horsepower.
The Commission-lake rule and the Game Commission's State game lands rule don't set horsepower caps; they ban gas engines.
On Fish and Boat Commission lakes no gas engine may propel a boat or power its motor. 58 Pa. Code §53.8(a).
On State game lands: no gas motors; electric motors at slow, no-wake only, unless the water is posted closed. 58 Pa. Code §135.41(c)(8).
PFBC's Boating FAQ: all Fish and Boat Commission and Game Commission lakes are electric-motors-only. PFBC Boating FAQs: horsepower question.
A bigger motor on board
Where Chapter 111 sets a horsepower limit, it applies to gas and electric motors; a boat with a bigger motor may launch, but that motor may not be used. 58 Pa. Code §107.1.
Read the exact wording
On waters where horsepower limitations are prescribed, as set forth in Chapter 111 (relating to special regulations counties), horsepower limitations apply to both internal combustion motors and electric motors. Boats with motors larger than the maximum horsepower shall be permitted but the motors may not be used.
On state-park lakes, check with the park office before launching with a motor above the posted limit.
"No limit listed" is not "unlimited"
When a lake's Chapter 111 rules list no horsepower cap, we say 'No horsepower limit listed in §111.x'. We say 'Unlimited horsepower' only where DCNR's table says 'unlimited'.