* Boat may pitch - Pitching is a rhythmic rising and falling of the bow of the boat. A pitching boat appears to be slapping the water. It's often called "porpoising." Some boats may pitch at low speeds, but this must disappear as the boat increases in speed. If pitching develops at high boat speed and corrections are not made to stop it, the bow of the boat might rise into the wind allowing the boat to blow over backwards or the boat's bow may plow into the water and go under or spin violently.

* Boat may roll - From the rear, a rolling boat would appear to flop from side to side. This rolling can also be described as "chine walking." At high speed very little of the boat's bottom is in the water. If the forces holding the boat upright on this small area become unbalanced, the boat may "fall off" sideways putting more of the boat bottom into the water. The water will then push the boat up and cause the boat to flop over on its other side. This rolling motion must be checked or the boat may start to "yaw" or catch the water sideways and flip over.

* Boat may yaw - The bow of a yawing boat will swing from side to side. Yawing often develops from an earlier unchecked chine walking condition. If a yawing condition is not corrected, steering control can be lost. The boat may flip over backwards, sideways, or catch its bow in the water and spin rapidly ejecting occupants.

(4) Steering Forces  

There are various steering forces that might be felt through the steering wheel on a mechanically steered rig. If your outboard is equipped with power steering, these forces are controlled by the power steering system. You will not feel external steering forces while the power steering system is functioning properly. If the power steering system is not functioning, operate at moderate speed until it can be repaired.

As the motor's propeller grabs and spins in the water, it causes twisting forces on the motor. These twisting forces or torque are felt as forces trying to twist the steering wheel out of the driver's hands. At high boat speeds the driver must put a correcting force on the steering wheel when the motor is trimmed up, to hold the motor's steering forces, even for a second or two, the driver must quickly relax the corrective force on the steering wheel or the boat will suddenly turn. Turning the boat at high speed is always very touchy so it is important that you know some of the things that can affect motor steering forces. Equipped with a right hand propeller, these forces are:

* Propeller blow out - Propeller "blow out" can affect the motor steering forces very suddenly. For a propeller to do its job, its blades must bite into undisturbed water. At some boat speeds, certain conditions of pressure and water flow may develop at the gearcase disrupting the smooth flow of water along its surface. Nearby air from the water's surface, or exhaust gases from behind the propeller, are pulled forward toward the sides of the gearcase. Suddenly the propeller blades and gearcase are surrounded by bubbles. Forward thrust and motor steering forces are gone. If you are correcting for external steering forces when "blow out" occurs, the boat could turn to the left suddenly.

* Ventilation - The trim angle of the motor or the location of the anti-ventilation plate of the motor with respect to the surface of the water can result in air from the water's surface being pulled into the propeller blade area. The propeller cannot grip this disturbed water and motor steering forces will drop suddenly.

Unlike propeller blow out, ventilation can occur at almost any speed but is most serious at high speed where the engine is trimmed out and the propeller is raised out of the water.

* Trim tab leaving the water - When the motor trim tab is correctly set, it helps you steer the boat by balancing some of the steering force. Without the tab, the driver would have to use greater effort at the steering wheel to hold the boat on course.

If you are holding the wheel against a steering force and the trim tab suddenly leaves the water, (for example when driving over the wake of another boat), you will feel a sudden change in forces at the steering wheel. The trim tab will no longer be helping you, and unless you anticipate this change in steering wheel force, the boat will naturally turn towards the left. Be aware that if you are running a high transom boat, the trim tab will usually be out of the water whenever the boat is on plane and the motor is trimmed UP, so all the steering forces will be felt at the wheel.

* Trimming the motor from full DOWN to full UP - When the motor is trimmed to full DOWN, the boat's bow will want to go deeper into the water. If the bow of the boat plows into the water, the boat may tend to bow steer or spin rapidly and eject the occupants.

When the motor is trimmed full DOWN you must exert a constant force to the steering wheel to keep the boat on a straight ahead path. As you trim the motor UP, the steering forces will become lighter, then the motor's steering torque will reverse and you will have to apply a force to the wheel in the opposite direction to keep the boat on a straight ahead path. If trimming is done at relatively high boat speed, the sudden steering torque reversals may cause a driver to lose control of the boat.

* Closing the throttle too fast - If you close the throttle suddenly while at high boat speed with the motor trimmed UP, the motor steering torque will stop abruptly. Since you were exerting a strong correcting force to the steering wheel against the earlier motor steering torque, the steering wheel could get away from you and put you into a hard turn which could be very dangerous. Unless there is some other reason to do so, always slow the boat gradually.

There are two conditions you should know about when stopping the boat.
One: a motor in trimmed UP position has less braking ability than a boat with its motor trimmed DOWN. When trimmed UP, you will need more room to come to a stop.

Two: if your boat is stern heavy, watch out for a following wave which will develop behind you as you come off plane. A following wave can break over the transom and spill into the boat.

The Motor

Safety Warning: Your dealer should install your motor and steering system. Improper motor installation could result in unexpected boat operation which could result in injury to the operator, passengers, or bystanders.

Complete the "break-in" procedure before running the motor at full throttle for an extended period of time. Refer to your Owner's Manual and Service Manual for the complete "break-in" procedure.

Steering Systems 

Safety Warning: Failure to use care in the selection and installation of remote steering system parts may contribute to steering system severance or jamming and sudden unexpected loss of boat control.

Safety Warning: If you use a "cable over pulley" steering system in conjunction with "racing" style steering arms,
the installation must not allow a significant change in cable tension when the engine is moved through its trim and tilt range. Loose steering cable could cause the system to jam or fail, resulting in unexpected loss of boat control.

The boat's steering system is important to the control of the boat and to the safety of the boat's occupants and others in the area. High performance boating requires special attention to the steering system to provide the highest degree of stability and control to the operator.

If your boat is equipped with a mechanical, push-pull cable system, all system components must meet or exceed the requirements outlined in ABYC Standard P-17. If your boat is equipped with a hydraulic system, the manufacturer or your dealer must verify that the system's capacity is sufficient for your application.

To complete the steering system, make sure you choose a large steering wheel with substantial finger grooves. At high speeds the driver will have to hold the wheel against forces trying to twist it out of his hands. Under some circumstances these forces change directions suddenly. Small wheels look nice but the smaller the wheel, the greater the effort required to overcome steering forces at the engine. Use the largest wheel that fits comfortably in your boat, and is recommended by the steering system manufacturer.

Once installed and connected, the system should be checked to ensure there is clearance between all steering system parts and the boat structure or other equipment in the transom area. Undetected interference can result in part breakage or weakening if the motor strikes an underwater object and tilts rapidly into the boat. Check by turning from lock to lock in both running and full tilt positions. Make sure all cable bends are not less than manufacturer's recommended minimum radius.

Safety Warning: Failure to check for interference may result in sudden, unexpected loss of boat control.

Keep the steering system manufacturer's installation instructions with your Owner's Manual. The instructions contain maintenance and testing information that is important for future reference.

Propellers 

When choosing a propeller for a high performance boat, the choice is really among the various stainless steel  propellers. While the aluminum propellers are good, their thicker blades are simply less efficient than the thin sectioned stainless steel propellers.

Note: When an aluminum propeller is replaced by a stainless steel propeller, the likelihood of drive-train breakage increases if you were to strike a submerged object.

The pitch of the optimum propeller for any particular sport boat can only be determined in on-the-water testing. Ultimately, you'll want the boat to run as fast as possible while staying within the motor's recommended full throttle operating range and while still providing acceptable all-around performance.

A quick look at the propeller selection guide included with your owner's kit will reveal a large choice of propeller sizes and types. The boat builder often has tested your rig with different propellers and often they will have a copy of the test results. Also check with others who are running similar rigs and see what style and size they are using, as your starting point.

Once a propeller style is chosen, you must run the boat to determine its operating characteristics. Items to check include:

* Engine operating RPM
* Boat speed
* Propeller ventilation
* Boat's planing ability

Assuming engine RPM is within the full throttle operating range and there is little or no ventilation when trimmed for the best running attitude, most motors can be raised one notch using the adjustable stern brackets. Repeat the test run and note the effects on the operating characteristics listed above. If motor ventilation is still not excessive at best trim, raise the motor again and retest.

The objective of all these tests is to run at the upper end of the full throttle operating range using the highest transom setting possible without excessive ventilation and while retaining an acceptable ability to get onto plane and trim the boat. You will have to experiment with different height settings and propeller pitches to find the best combination for this particular rig. You may also reach a point where you can no longer operate with all the positive trim your boat needs for best speed. In this case, lower is better. Remember though, as you continue raising the motor, it is essential that you keep an eye on the water pressure gauge. If there is a drop in pressure at any particular motor height setting, you will have to drop back a notch or risk serious engine damage.