# What is apparent wind in sailing?

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## What is TWA in sailing?

In addition, there is the term TWA (True Wind Angle) which is the angle between the boat’s heading and the true wind direction (TWD).

## What is relative wind speed?

In aeronautics, the relative wind is the direction of movement of the atmosphere relative to an aircraft or an airfoil. It is opposite to the direction of movement of the aircraft or airfoil relative to the atmosphere. … This vector is the relative wind or the free stream velocity vector.

## What is geostrophic wind scale?

[¦jē·ō¦sträf·ik ′wind ‚skāl] (meteorology) A graphical device used for the determination of the speed of the geostrophic wind from the isobar or contour-line spacing on a synoptic chart; it is a nomogram representing solutions of the geostrophic-wind equation.

## Why are additive wind velocities important?

The reason for including a wind additive to your approach speed is clearly designed to prevent landing with too little stall margin should the winds change. But landing with too much speed presents its own set of problems.

## What does UFD mean in sailing?

UFD: Meaning U-Flagged – a ruling where a boat is deemed to have prematurely started a race that is started under “U” Flag and is disqualified from that race and awarded the maximum number of points, unless that race is subsequently restarted.

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## What is SOG in sailing?

Speed Over the Ground (SOG) is the speed of the vessel relative to the surface of the earth. Speed Through Water (STW) is the speed of the vessel relative to the water. It is possible for the STW to be zero while the SOG is 5 knots, for example if the boat was drifting in a 5 knot current.

## What does btw mean in sailing?

B. Bathymetric charts. Bathmetric charts are a visual representation of underwater terrain; they show contours of the area beneath water in a similar way to how a topographic map shows the lay of the land above water. Boat Speed. Speed at which the boat is travelling through the water along its current course.