Fastening The Outboard - Mercury 25 EFI Service Manual

• Installing the outboard too low on the transom will allow excessive drag.
Boats with a "V" Bottom Hull
1. Measure the width of the leading edge on the water intake housing. Make a horizontal line on the transom up from the "V"
bottom the same length as the width of the water intake housing.
2. Place (center) the outboard on the boat transom. Set the height of the outboard on the boat transom so that the front edge
of the water intake housing is in line with the horizontal line made in step 1. Temporarily clamp the outboard to the transom
at this position.
3. Fasten the outboard to the transom at this height. Refer to Fastening the Outboard.
Boats with a Flat Bottom Hull
1. Place (center) the outboard on the boat transom. Set the height of the outboard on the boat transom so that the front edge
of the water intake housing is in line with the bottom of the boat as shown. Temporarily clamp the outboard to the transom
at this position.
2. Fasten outboard to the transom at this height. Refer to Fastening the Outboard.

Fastening the Outboard

1. Drill four 13.5 mm (17/32 in.) mounting holes.
2. Install the outboard so that the water intake housing is set at the correct height. Refer to Determining the Mounting
Height of the Outboard Jet.
3. Apply marine sealer to shanks of bolts (purchase locally). Do not apply marine sealer to the threads of the bolts.
4. Fasten the outboard with provided mounting hardware shown. Tighten mounting hardware securely.
90-8M0105568 eng MARCH 2016
a
b
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a - Horizontal line
b - Width of the leading edge on the water intake housing
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© 2016 Mercury Marine
Outboard Installation
Page 1D-11