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航行方向与帆的调整Points of Sail and Sail Trim









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发表于 2015-10-26 22:07 | 显示全部楼层 |阅读模式


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Points of Sail and Sail Trim


Points of Sail by Wind Direction航行方向取决于方向
different,relative,points,refers,terms 航行方向与帆的调整Points of Sail and Sail Trim

© Tom Lochhaas.
“Point of sail” refers to the angle of the sailboat to the directionfrom which the wind is blowing. Different terms are used for the differentpoints of sail, and the sails must be trimmed into different positions fordifferent points of sail.


Consider this diagram,which shows the basic points of sail for different boat directions relative tothe wind. Here, the wind is blowing from the top of the diagram (think of it asnorth).

上图展示了几种基本的航行方向 – 相对于风向的船头方向。图中风从图的上面吹来(假定为正北方向)。

A sailboat sailing closeto the wind on either side (toward the northwest or northeast) is close hauled.Sailing directly across the wind (due west or due east) is called a beam reach.Off the wind (to the southwest or southeast) is called a broad reach. Directlydownwind (due south) is called running.


Next we’ll look at each of these points of sail and how thesails are trimmed for each.


Close Hauled  侧风行驶
different,relative,points,refers,terms 航行方向与帆的调整Points of Sail and Sail Trim

Photo © Tom Lochhaas.

Here the sailboat is sailing close hauled, or asclose to the wind direction it can.


Most boatscan sail within about 45 to 50 degrees of the wind direction. (No boat can saildirectly into thewind.) Close hauled is also called beating.
Notice that both sailsare pulled in tight, and the boom is centered down the centerline of the boat.The curve of the sails is like the shape of an airplane’s wing, generatinglift—a force that, in combination with the effect of the keel, results in theboat being pulled forward.


Note that the boat isalso heeling (leaning) to starboard (the right side). Sailing close hauledproduces more heeling than other points of sail.


When close hauled, the jib is trimmed in tight for equal airflowon both sides.


Beam Reach横风
different,relative,points,refers,terms 航行方向与帆的调整Points of Sail and Sail Trim

Photo © Tom Lochhaas.
In a beam reach, the boat is sailing at a perpendicular angle tothe wind. The wind is coming directly across the beam of the boat.


Notice that the sailsare let out farther in a beam reach than when close hauled. The flow of thewind over the curve of the sail is, again, like air around an airplane’s wing,generating lift to move the boat forward.


Note too that the boatheels less than when close hauled.


All other factors being equal, beam reach is often the fastestpoint of sail for most sailboats.


Broad Reach顺风航行
different,relative,points,refers,terms 航行方向与帆的调整Points of Sail and Sail Trim

Photo © Tom Lochhaas.
In a broad reach, the boat is sailing far off the wind (but notquite directly downwind). Note that in a broad reach the sails are let muchfarther out. The boom is far out to the side, and the jib loops forward of theforestay.


The shape of the sailsis still generating some lift, but as the boat heads farther and farther offthe wind, it is increasingly being pushed forward by the wind from behindrather than being pulled forward by lift.

主帆的形状仍然可以产生推力,但是由于船头偏离方向越来越远。船帆受到的风的推力越来越大 – 大于帆面形状产生的推力。

Note also that the mainsail out to the side is almost directlybehind the jib, in relation to the wind coming from behind. If this boat weresailing directly downwind, the mainsail would block the wind and keep so muchwind from the jib that it would not fill. Most sailors therefore prefer to sailoff the wind in a broad reach rather than directly downwind. A broad reach is faster,and there is less risk of an accidental gybe. A gybe occurs when headeddownwind and a wind shift or gust throws the mainsail across to the other side,stressing the rigging and risking the boom striking someone as it crosses theboat.



Running Wing on Wing正顺风
different,relative,points,refers,terms 航行方向与帆的调整Points of Sail and Sail Trim

Photo © Tom Lochhaas.
As mentioned on the previous page, it is inefficient to saildirectly downwind with both sails on the same side, because the mainsail willblock the wind from the jib.


One way to prevent thisproblem is to run downwind with the sails on opposite sides of the boat tocapture the wind on both sides. This is called sailing wing on wing and isshown in this photo. Here, the main is far out to starboard (the right side)and the jib is far out to port.


Because it is stilloften difficult to keep both sails full and drawing downwind, especially if theboat is rolling side to side on waves, the jib can be held out to the side witha whisker pole or spinnaker pole. As you can see in this photo, the jib’s outercorner (the clew) is poled to port with a pole mounted to the mast. In a lightwind the wight of the jib may still make it droop or flutter, even when poledout. As you can see in this photo, the leading edge of the jib (the luff) isnot being blown fully forward in this light air.


Running downwind isgenerally considered the slowest point of sail.


Remember that the sails are trimmed differently for each pointof sail.


Here are two apps for Apple devices that can help you learn or teach about pointsof sail.

the original articles are from the website "aboutsport". if covering torts, please contact us to delete.


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