Explanation: A 'point of sail' fundamentally describes a sailing craft's direction of travel in relation to the true wind vector, encompassing how the vessel is oriented relative to the wind.

Explanation: A 'point of sail' is a technical term that delineates a sailing craft's trajectory relative to the prevailing true wind. It fundamentally characterizes the vessel's orientation with respect to the wind vector.

Explanation: 'Starboard tack' refers to the side on which the wind is coming (from the starboard side), not a point of sail which describes the direction relative to the wind.

Explanation: Sailing 'close-hauled' signifies a point of sail where the craft is oriented as directly into the wind as possible, typically around 45 degrees off the true wind, not with the wind coming from behind.

Explanation: A 'beam reach' is a point of sail characterized by the true wind approaching from the side of the craft, precisely perpendicular (90 degrees) to its direction of travel.

Explanation: A 'broad reach' is a point of sail where the wind originates from behind the craft but not directly astern, typically at an angle of approximately 135 degrees, whereas direct wind from behind is 'running downwind'.

Explanation: Reaching points of sail are generally associated with high speeds for sailing craft, as they efficiently utilize sail lift.

Explanation: A 'close reach' involves sailing with the wind coming from the side, at an angle closer to the wind than a beam reach, not directly astern.

Explanation: A 'broad reach' is defined as having the true wind coming from an angle of approximately 135 degrees relative to the craft's course.

Explanation: When sailing directly downwind, a craft's speed cannot exceed the true wind speed.

Explanation: A 'spinnaker' is a large, lightweight sail primarily used for downwind or broad reaching, not for sailing close-hauled.

Explanation: 'Wing on wing' describes a configuration for sailing dead downwind where the mainsail and jib are set on opposite sides of the boat.

Explanation: According to an image caption, boat speed is highest on a beam reach because the apparent wind dynamics and sail forces are optimal for speed, not necessarily due to a significant increase in apparent wind itself.

Explanation: When sailing on a broad reach, the sails are typically eased out, not trimmed tightly as they are when sailing close-hauled.

Explanation: A craft sailing at approximately 45 degrees off the true wind is considered to be on a close-hauled course, the closest point of sail to the wind.

Explanation: A sailing craft typically achieves its highest speeds on reaching points of sail, not when sailing directly downwind, where speed is limited by the true wind speed.

Explanation: A craft is on a beam reach when the true wind is coming from a direction precisely 90 degrees relative to its course, i.e., directly from the side.

Explanation: Sailing close-hauled requires the sails to be trimmed in tightly to maximize lift and sail as close to the wind as possible.

Explanation: 'Beating', also referred to as sailing 'close-hauled', denotes the point of sail where a craft navigates as closely as possible to the true wind, typically at an angle of approximately 45 degrees, with sails trimmed taut.

Explanation: A craft is considered to be on a 'beam reach' when the true wind originates from a direction precisely perpendicular (90 degrees) to its course of travel, impacting the vessel's beam.

Explanation: The point of sail positioned between the close-hauled course and a beam reach is termed a 'close reach'. In this configuration, the wind approaches from the side at an angle sharper than that of a beam reach.

Explanation: 'Running downwind' is the point of sail where the craft travels directly in alignment with the true wind, experiencing the wind originating from directly astern (180 degrees).

Explanation: Reaching points of sail typically facilitate the highest speeds for sailing craft because the sails generate significant lift, a more efficient propulsive force than drag, potentially enabling speeds exceeding the true wind.

Explanation: A 'spinnaker' is a large, lightweight sail, often characterized by its balloon-like shape, primarily utilized on fore-and-aft rigged vessels. It is typically deployed during downwind or broad reach conditions to maximize the sail area exposed to the wind.

Explanation: 'Wing on wing' refers to a sail configuration employed by fore-and-aft rigged vessels when sailing dead downwind, characterized by the mainsail and jib being set on opposite sides of the boat, resembling wings.

Explanation: This caption explains that the accompanying diagram illustrates the dynamics of apparent wind and forces on a sailboat as it deviates from the true wind's direction. It highlights that apparent wind and lateral force diminish, while boat speed reaches its maximum on a beam reach.

Explanation: When sailing directly downwind, a sailing craft's speed through the water is fundamentally limited and cannot exceed the speed of the true wind.

Explanation: 'Velocity made good' refers to the effective speed towards a destination. For downwind sailing, achieving a higher velocity made good may involve sailing on efficient broad reaches and executing jibing maneuvers, rather than sailing dead downwind, if the increased speed on the reach compensates for the longer course.

Explanation: When running downwind, the primary force propelling the craft is drag, not lift, generated by the sails acting more like parachutes pushed by the wind.

Explanation: Apparent wind is the wind velocity experienced by a moving observer or craft, not a stationary one. True wind is measured by a stationary observer.

Explanation: The apparent wind is indeed the vector sum of the true wind velocity and the craft's own velocity, representing the wind experienced by the moving vessel.

Explanation: A sail generates lift when the apparent wind is angled across its surface, similar to an airfoil; when perpendicular, drag is more dominant.

Explanation: As a sailing craft transitions from close-hauled towards running downwind, the lifting force generated by the sails decreases, while drag increases.

Explanation: Apparent wind velocity (VA) measures the wind speed relative to the moving craft, not a fixed point on land. True wind is measured relative to a fixed point.

Explanation: The image caption 'Points of sail and approximate apparent wind for a conventional sailboat on starboard tack' refers to the apparent wind experienced by the moving sailboat, not a stationary observer.

Explanation: When sailing close-hauled, the sails primarily rely on lift, not drag, to propel the craft.

Explanation: True wind is the actual wind velocity measured relative to a fixed point, whereas apparent wind is measured relative to the moving craft.

Explanation: The motive power for a sailing craft is determined by the apparent wind, which is a combination of the true wind and the craft's velocity, not solely the true wind.

Explanation: The primary force generated when airflow is angled across a sail's surface, similar to an airfoil, is lift, not drag.

Explanation: Apparent wind speed is not always equal to true wind speed when the craft is moving; it varies depending on the craft's velocity and the true wind.

Explanation: A craft sailing directly downwind relies primarily on drag for propulsion, not lift.

Explanation: The motive power for a sailing craft is fundamentally determined by the apparent wind, which is the resultant wind experienced relative to the moving craft. This apparent wind is a vector sum influenced by both the true wind and the craft's own velocity.

Explanation: When airflow is angled across its surface, a sail functions similarly to an airplane wing, generating lift as its primary propulsive force, acting perpendicular to the sail's plane.

Explanation: As a sailing craft transitions from a close-hauled course towards running directly downwind, the magnitude of the lifting force generated by the sails diminishes, while the drag force acting upon them correspondingly increases.

Explanation: 'Apparent wind velocity' (VA) denotes the speed and direction of the wind as perceived by an observer or instrument situated on a moving sailing craft. It is the resultant vector combining the true wind and the craft's own velocity.

Explanation: When sailing close-hauled, sails function analogously to wings, generating lift from the apparent wind. This lift, acting perpendicular to the sail's surface, propels the craft forward.

Explanation: The 'no-go zone' is a region relative to the true wind where sailing craft cannot effectively sail directly into the wind due to insufficient lift generation.

Explanation: The no-go zone typically encompasses approximately 90 degrees of the area around the direction of the true wind, divided equally on either side.

Explanation: The width of the no-go zone is influenced by sail efficiency and the craft's lateral resistance, not solely by sail size.

Explanation: Being 'in irons' signifies that a sailing craft has stalled within the no-go zone, unable to generate propulsion because its sails are not correctly angled to the apparent wind.

Explanation: Recovering from being 'in irons' typically requires maneuvering the craft out of the no-go zone, not sailing faster directly into the wind.

Explanation: 'Pinching' occurs when a sailing craft sails too close to the no-go zone, resulting in a significant loss of speed, not excessive speed.

Explanation: A craft is considered 'weatherly' if it performs well when sailing upwind, demonstrating superior ability to point into the wind or maintain speed compared to other craft.

Explanation: Sailboats cannot make progress directly upwind; they must employ a zig-zag pattern, known as beating, to move against the wind.

Explanation: 'Tacking' or 'going about' is a maneuver where the bow of the boat passes through the wind, not the stern. Jibing involves turning the stern through the wind.

Explanation: The image caption about iceboats 'in irons' indicates their sails are slack and not generating power, signifying a stalled state.

Explanation: A more 'weatherly' watercraft sails closer to the wind and makes better progress upwind, contrary to the statement that it performs poorly.

Explanation: Tacking and jibing are distinct maneuvers; tacking involves turning the bow through the wind, while jibing involves turning the stern through the wind.

Explanation: A sailing craft must use a zig-zag pattern, known as beating, to make progress towards the direction of the true wind, as direct upwind travel is impossible.

Explanation: The 'no-go zone' prevents a sailing craft from sailing directly upwind, not downwind.

Explanation: The maneuver of turning the stern through the wind is called jibing, while tacking involves turning the bow through the wind.

Explanation: The 'no-go zone' is approximately 45 degrees wide on each side of the true wind's direction, totaling about 90 degrees.

Explanation: The 'no-go zone' is a region extending approximately 45 degrees on either side of the true wind direction, within which a sail cannot effectively generate propulsion. Entry into or prolonged presence within this zone results in a loss of momentum and eventual cessation of movement.

Explanation: The 'no-go zone' typically extends approximately 45 degrees on either side of the true wind's direction, constituting a total angular range of about 90 degrees within which direct upwind propulsion is infeasible.

Explanation: Being 'in irons' signifies that a sailing craft has become stalled within the 'no-go zone', rendering its sails incapable of generating propulsion due to improper angling relative to the apparent wind.

Explanation: 'Pinching' describes the condition where a sailing craft's course becomes excessively close to the 'no-go zone', leading to a substantial reduction in speed as the sails lose their capacity to generate effective lift.

Explanation: To achieve progress upwind, sailing craft must utilize a zig-zagging pattern across the direction of the oncoming wind, a maneuver known as beating to windward.

Explanation: 'Tacking', also termed 'going about', is the maneuver wherein a sailing craft turns its bow through the wind to transition from sailing on one side of the wind to the other, a critical technique for upwind progress.

Explanation: This caption describes iceboats that are stationary within the 'no-go zone', with their sails slack and passively flapping, indicating a state of non-propulsion.

Explanation: 'Tacking' involves turning the bow of the boat through the wind to change tacks, typically employed when sailing upwind. 'Jibing' involves turning the stern of the boat through the wind, usually performed when sailing downwind.

Explanation: Studding sails were used on square-rigged vessels to increase sail area, particularly in light winds, not decrease it.

Explanation: Sailboats utilize underwater appendages, such as keels or foils, to generate lateral resistance, counteracting sideways motion (leeway).

Explanation: Ice boats do not rely on keels to prevent heeling; their runners on ice provide lateral resistance without significant heeling, unlike sailboats which use keels or foils.

Explanation: For iceboats, apparent wind dynamics are such that it increases slightly as they sail further from the true wind's direction, with peak speed often achieved on a broad reach.

Explanation: The angular width of the 'no-go zone' is influenced by the aerodynamic efficiency of the craft's sails and its capacity for lateral resistance, provided by elements such as keels or foils in water, or runners on ice.

Explanation: 'Studding sails' were supplementary sails attached to the yardarms of square-rigged vessels, primarily utilized in conditions of light wind to augment the total sail area and enhance performance across various points of sail.

Explanation: Sailboats utilize underwater appendages, such as keels or foils, to generate lateral resistance, counteracting the sideways force (leeway) generated by the wind acting upon their sails and thereby minimizing sideways drift.

Explanation: Sailboats counteract lateral forces using underwater appendages (keels, foils) for resistance and hull design for stability against heeling. Ice boats, conversely, rely on the lateral resistance of their runners on ice, which typically precludes significant heeling.