Screw gunvessel HNLMS Makassar (1877–1893) Cf the topmast Originally the class was designed for a schooner sail plan, but this was later changed to a barquentine sail plan. The total surface of the sails of the Samarang on a close-hauled point of sail was 839.5 square meters. In 1876 the Samarang sailed at beam reach (point of sail) in a fresh breeze (in Dutch: a stijve marszeils koelte, 5 bft) and reached 8.25 knots. The topmast of all ships that followed the Samarang was shorter, which greatly influenced the surface of their sails.
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Marchaj attributes the large lifting power of the sail to lift generated by the vortices, while others attribute the power to a favourable mix of aspect ratio, camber and (lack of) twist at this point of sail. A more modern academic wind tunnel study (2014) provided similar results, with the Santa Cruz Islands tepukei's crab claw sail configuration dominating measurements.
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The sum of those two drag angles are equal to β, the angle between the apparent wind and the course sailed (β = λ + αm). This theorem applies for every point of sail. A small β denotes high efficiency and a potential for high speed. As forward velocity increases, β becomes smaller; on sailing craft with effective underwater foils the drag angle of the hull, λ, becomes smaller with increased speed, it becomes negligible with hydrofoiling craft, and essentially nonexistent for ice boats and land sailing craft.
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In the event that two boats on opposite tacks are on a collision course, one or both of the captains may elect to call "hard lee" to the other. When this call is made, both boats must tack regardless of whether it is advantageous or not. The objective of this manoeuvre is to attempt to gain as much distance upwind as possible before having to tack to avoid a collision. Alternatively, one captain may decide to "draw" and either tack earlier or change his point of sail to avoid the manoeuvre.
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Aircraft carrier HMS Illustrious leading the contestants in the 2011-12 race down Southampton Water to the start line off Cowes, IoW, 31 July 2011, as seen from Calshot Spit. The race ran every two years between 1996 and 2002, and then skipped a year, with subsequent races beginning in 2005, 2007, 2009, 2011, 2013, 2015, 2017 and 2019. The routes used for the races have varied slightly each race. The routes are selected to allow for a high proportion of downwind sailing, the most technically demanding point of sail.
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Sailing into the wind is a sailing expression that refers to a sail boat's ability to move forward even if it is headed into (or very nearly into) the wind. A sailboat cannot make headway by sailing directly into the wind (see "Discussion," below); the point of sail into the wind is called "close hauled". Sailing into the wind is possible when the sail is angled in a slightly more forward direction than the sail force. In that aspect, the boat moves forward because the keel (centreline) of the boat acts to the water as the sail acts to the wind.
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The B&R; 23 is very agile, reacting immediately to the tiniest changes in conditions, demanding a high level of alertness and very proactive sailing by the crew, who must be fully synchronised in all their actions on board. Upwind, the boat is able to plane under ideal conditions, however, the best point of sail for a B&R; 23 is downwind. Being an apparent wind boat, it will rarely if ever be sailed directly downwind, instead, optimum downwind performance is achieved by gybing downwind while reaching somewhere around 150 degrees TWA, which typically results in AWA’s forward of beam. In most conditions, boat speed will easily exceed wind speed, and in favorable conditions, getting close to factor 2.
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She took off quick and we could feel her accelerate ... Close hauled she will sail to within 50 degrees of true wind, but at 60 to 70 degrees is her best point of sail, she heeled gracefully, found her groove, maintained 7.02 kts and rode the waves with little to no pounding. With her high bow she'll split through and roil the waves aside with ease. When the gust came she dipped her teak toecap for few seconds, kissed 37-40 degrees of heel, shook-off the gust and then returned to the original 30 degrees. She did not want to round up, the weather helm was minimal and there were no surprises.
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Angle of attack is often constrained by the sailing craft's orientation to the wind or point of sail. On points of sail where it is possible to align the leading edge of the sail with the apparent wind, the sail may act as an airfoil, generating propulsive force as air passes along its surface—just as an airplane wing generates lift—which predominates over aerodynamic drag retarding forward motion. The more that the angle of attack diverges from the apparent wind as a sailing craft turns downwind, the more drag increases and lift decreases as propulsive forces, until a sail going downwind is predominated by drag forces. Sails are unable to generate propulsive force if they are aligned too closely to the wind.
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The ship has over of running rigging and approximately of sail area. To protect sails from chafing, Eagle uses baggywrinkle extensively. The top three yards of the fore- and main masts are moveable, and are kept lowered when not sailing to lower the ship's center of gravity. In addition, the top portion of the fore- and main masts, known as the topgallant masts, may be housed (lowered) by 13 ft when not under sail in order to sail underneath low bridges. Eagles fastest point of sail is when her yards are braced sharp (or pivoted as much as they can be) and the relative wind (the wind you feel standing on the ship as it moves) is approximately 5-10 degrees aft of the windward leech of the sail. When fully braced, Eagle can sail about 75 degrees off of the true wind.
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In sailing, luffing refers to when a sailing vessel is steered far enough toward the direction of the wind ("windward"), or the sheet controlling a sail is eased so far past optimal trim, that airflow over the surfaces of the sail is disrupted and the sail begins to "flap" or "luff" (the luff of the sail is usually where this first becomes evident). This is not always done in error; for example, the sails will luff when the bow of the boat passes through the direction of the wind as the sailboat is tacked. A sailboat can also be "luffed" slightly without completely de-powering the sails. Often this occurs on the point of sail known as close hauled, this is sometimes referred to as pinching or "feathering" and is sometimes done deliberately in order to make a more direct course toward an upwind destination (see: "beating to windward"), or to "de-power" a sail on a windy day to maintain control of the sailboat.
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