BASIC POWERBOATING. SAFETY & RESCUE FOR SAILING INSTRUCTORS 23


Wind Direction Clues E smoke from a smokestack E flags onshore


E boats on moorings (usually point into the wind unless being affected by current)


E ripples or waves


E wind on your face (boat has to be stopped)


Boats have a tendency to turn away from the wind.


WIND WINDAGE


Wind will have an important effect on almost all of your boat- handling maneuvers, especially when you operate at lower speeds in moderate to strong wind conditions. The wind’s impact also varies with the amount of the boat’s surface area (windage) that the wind can push against. Boats with high topsides, cabins and flying bridges have greater windage than boats with lower profiles.


When drifting, the wind will usually cause the bow to “fall off” until the boat lies across the wind or even with the stern toward the wind. This tendency to turn away from the wind is an important consideration when holding a boat in position.


When turning into the wind, windage reduces your speed and tightens your turning arc. This can be beneficial when maneuvering in a confined area.


When turning with the wind, windage increases your speed and enlarges your turning arc.


UNDERWATER HULL SHAPE Windage and Speed


When turning into the wind, windage reduces your speed and tightens your turning arc.


A boat’s underwater hull shape will affect its steering characteristics. Boats with minimal underwater profile, such as soft-inflatables, will tend to skid or sideslip along the surface of the water as they turn, thereby increasing the turning arc. Turning this type of boat in windy conditions in a confined area is a true boat handling challenge.


MINIMUM CONTROL SPEED


When turning with the wind, windage


increases your speed and enlarges your turning arc.


WIND


Minimum control speed (mcs) is the slowest speed at which you can operate and still maintain steering control. Typically, this is less than the speed produced when the engine is in gear and the throttle is set at idle rpm, and is accomplished by the use of intermittent power. With the throttle at idle rpm, shift from neutral to forward and back to neutral. This produces a short, gentle pulse of power to maintain steering control. Repeat this technique to keep the boat under control and moving slowly. Minimum control speed is used in many situations, such as docking and operating in confined areas.


To make turns at minimum control speed, turn the wheel (helm) in the desired direction and shift into forward gear at idle rpm to start the turn, then back to neutral near the end of the turn. As a result of the directed thrust from the propeller (or increased water flow over the turned rudder), the boat will turn but not accelerate significantly. When using intermittent power to turn, avoid oversteering and using too much throttle to prevent loss of steering control.


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