Page 338 - REPOWER REFERENCE GUIDE (2020)

Steering Systems
High Speed or Twin Engine Applications Steering Recommendation

Refer to Multiple Sterndrive Steering Tie Bar Arrangements.
Mercury MerCruiser power packages come standard with Mercury MerCruiser's internal power steering. This durable system
provides precise effortless steering control and is recommended for most sport boat applications. On certain applications,
however, Mercury MerCruiser recommends the use of an external power steering system where the power steering cylinders
connect directly to the sterndrive unit on the outside of the boat. This arrangement gives additional support for even tighter,
more firm steering control, and is recommended for the following applications:
• High speed single or twin engine applications and/or boats with unusual handling characteristics
NOTE: Boats with multiple sterndrives can be linked together with different tie bar arrangements. Adding external tie bars,
either in conjunction with internal tie bars, or an external steering cylinder, reduces the steering system backlash. This
reduced backlash may be either beneficial or necessary to provide more precise steering response when boat speeds
exceed 97 km/h (60 mph). Because of the many variables involved, the choice of which system to use on a given boat
rests with the boat manufacturer after test and evaluation of steering system response.
• Any high‑performance sport boat powered by three or more engines
• Offshore boats or other applications where the boat and sterndrive units may come out of the water occasionally
External power steering systems are generally either mechanical cable actuated or hydraulic actuated.
External power steering and hydraulic helm systems can be obtained from the following aftermarket suppliers:
Latham Marine, Inc.
280 S.W. 32nd Court
Ft. Lauderdale, FL 33315
Phone: (954) 462-3055
Fax (954) 462-3081
Bravo Three Notice: Trim‑In Limit Insert

NOTE: Bravo One, Two and Three Models are equipped with a trim‑in limit insert.
It has been brought to our attention that some boats (predominantly deep‑Vee heavy boats) will roll up on their side under
certain, specific, operating conditions. The roll can be either to port or starboard and may be experienced while moving straight
ahead, or while making a turn. The roll occurs most frequently at or near maximum speed, with the sterndrive unit trimmed at or
near full trim‑in. While the boat will not roll completely over, the roll may be sufficient to unseat the operator or passengers, and
thereby create an unsafe situation.
The roll is caused by stern lift created from excessive sterndrive unit trim‑in. Under these extreme stern lift/bow‑down
conditions instability can be created which may cause the boat to roll. Weight distribution to the stern can reduce stern lift and,
in some circumstances, help to control the condition. Weight distribution in the bow, port or starboard, may worsen the
condition.
The trim‑in limit insert reduces stern lift by preventing the sterndrive unit from reaching the last few degrees of full trim under.
While this device should reduce the rolling tendency, it may not eliminate the tendency entirely. The need for this trim‑in limit
insert, and its effectiveness, can only be determined through boat testing and is ultimately the responsibility of the boat
manufacturer.
! WARNING

On some boats, increased trim‑in range can cause handling problems at high speeds, resulting in personal injury or death.
We recommend that only qualified personnel adjust the trim‑in limit inserts and test the boat for handling problems.

Multiple Sterndrive Steering Tie Bar Arrangements
NOTE: Boats with multiple sterndrives can be linked together with different tie bar arrangements. Adding external tie bars,
either in conjunction with internal tie bars, or an external steering cylinder, reduces the steering system backlash. This reduced
backlash may be either beneficial or necessary to provide more precise steering response when boat speeds exceed 97 km/h
(60 mph). The products, speeds and tie bar configurations shown in the chart below are general recommendations. Because of
the many variables involved, the choice of which system to use on a given boat rests with the boat manufacturer after test and
evaluation of steering system response.
With multiple sterndrives you must select one of the following possible steering systems.
NOTICE

Incorrect tie bar installation can damage the drive and steering system. Do not let the tie bar contact other components during
severe turning conditions. Always calculate sufficient turning clearances, observe recommended tie bar arrangements, and
check for proper installation before operating the boat.

Page 9B-14 © 2019 Mercury Marine 90-8M0149179 eng NOVEMBER 2018