Water Level Guideline (4-Stroke Engines) - Yamaha F70AET Rigging Manual

MOUNTING THE OUTBOARD MOTOR

WATER LEVEL GUIDELINE (4-STROKE ENGINES)

If you replaced 2-stroke engine to 4-stroke engine which has the same horse power, a boat tends to
become "stern heavy" because of heavier engine weight.
As a result, water line will rise and get close to the power head.
This causes poor engine performance, and water could easily enter into the cylinder(s) and damage
the engine.
Therefore, you should consider the water level guideline when installing a 4-stroke outboard motor.
When mooring a boat with a maximum boat load, maintain the minimum height (H) shown in the
illustration between the water surface and the clamp bracket seating point.
(H)
Minimum height between water surface and bracket seating point
Model
Carbureted F2 – F60
Fuel injected F40 (4-cyl) – F70
F75 and above
Water surface
Min. height (H)
150 mm 5.9 in
100 mm 3.9 in
100 mm 3.9 in
1-9