Pivot points, windage and slide
Boat Handling Skills - Using the Wind and Pivot Points
As soon as you leave the pontoon, it is apparent that a boat has little in common with driving a car. In wind, a boat slides about on the surface and has no grip like car tyres have on a road. It is steered by a rudder positioned at the stern instead of in a car by the front wheels.
In fact, whilst it may be a strange analogy, a boat handles similar to a shopping trolley or wheelbarrow when turning. You swing out the back to point the front in the direction you want to go.
When a boat turns, the bow goes one way and the stern the other. Because the rudder is positioned aft, it is actually the stern of the boat being steered even though the bow is turning.
When motoring ahead a yacht pivots around a point roughly a third from the bow, roughly at the mast.
In ahead and when turning, beware of colliding with obstructions with your quarter.
In astern, the pivot point moves to a point 1/3rd from the stern. Monitor the bow when turning because it now swings the most.
Influence of wind
Wind has two effects on a boat when boathandling.
1)The bow always drifts downwind first - the bow has less grip in the water and more windage than the stern. A stalled yacht often sits beam or quarter to the wind.
2)A stopped or slow moving yacht will drift downwind. Good wind awareness is required to avoid drifting onto obstructions.
The easiest way to hold position in wind is to reverse gently and sit stern to wind. Reversing moves the pivot point aft enabling the bow to blow downwind.
Controlling a boat is similar to controlling a car on an icy road, if you turn one way, the cars slides the other. When turning a boat, the boats momentum tries to keep it going forward, the hull stalls in the water and the boat skids sideways. The amount of slide depends on how much speed was carried into the turn, the type of boat and underwater configuration.
Slide can be a hindrance when turning in a small area as the boat can slide out of the turn and onto dangers. It can also be used to assist berthing, by approaching a berth so that the slide drifts the boat alongside.
Simon Jinks, RYA Instructor and yachting journalist.
More information on Boat Handling
Article Published: August 31, 2010 16:08
Article Updated: July 24, 2013 13:42