4-6 CHAPTER 4: OPERATION
Sport Boat Owner’s Manual
Drive Trim Angle
Trim angle is the angular relationship between the lower drive unit and the tran-
som of the boat. Boat trim while underway greatly affects boat performance and
efficiency. For best results, the boat should be on plane and trimmed to reduce the
wetted surface. With less boat in the water, both speed and fuel economy
increases. Engines with manual trim must be adjusted for best overall operation
for the load and conditions. Engines with power trim should be adjusted continu-
ously for best results.
If the engine is trimmed in too far (closer to the boat bottom), speed drops, fuel
economy decreases, and the boat may not handle correctly. However, it does pro-
vide better acceleration from a stand still; and because it forces the bow down, vis-
ibility is improved. If the engine is trimmed out too far (away from the boat
bottom), steering torque may increase, the boat may be difficult to get on a plane,
and may bounce.
Do not trim the engine out too far or the boat may begin to “porpoise”
(bounce up and down). Porpoising reduces control and visibility.
To use power trim effectively, always start with the engine trimmed in. As the boat
planes, increase the angle out. Experience is the best teacher for understanding
proper trim.
CORRECT
IN TOO FAR
OUT TOO FAR
KC-1150
UP
TRIM
DN
UP
TRIM
DN
UP
TRIM
DN
!
WARNING