Brett Robson wrote:
> Bryce wrote:
>> "necoandjeff" <spam@schrepfer.com> wrote in message
>> news:NzFCd.8207$5R.5285@newssvr21.news.prodigy.com...
>>
>>> Ryan Ginstrom wrote:
>>>
>>>> "necoandjeff" <spam@schrepfer.com> wrote in message
>>>> news:31FCd.8196$5R.2764@newssvr21.news.prodigy.com...
>>>>
>>>>> Ryan Ginstrom wrote:
>>>>>
>>>>>>> But I much prefer
>>>>>>> sailing or boating. How is it even possible to not got where you
>>>>>>> intend to?
>>>>>>
>>>>>> 1. You want to go *this* way but the wind pushes you *that* way
>>>>>> 2. The wind won't push you anywhere at all
>>>>>> 3. You end up going upside down (assuming this is not the way you
>>>>>> intended to go)
>>>>>
>>>>> I can sort of understand 2 (except that the wind normally doesn't
>>>>> "push" you while sailing), but 1 and 3? Dude, you really suck at
>>>>> sailing...
>>>>
>>>> I never claimed otherwise. In fact, of the many things I suck at,
>>>> sailing figures prominently.
>>>>
>>>> But I've still got 20 years or so to learn.
>>>
>>> Lesson 1: The wind doesn't "push" the boat. Learn how airplane wings
>>> generate lift and you'll be well on your way to understanding how
>>> to sail.
>>>
>>>
>>
>>
>> I believe it "pulls" the boat. The differences in air pressure would
>> suggest this.
>>
>
> The force that is pushing is the high pressure under the
> airfoil,or in this case behind the sail. Low pressure doesn't
> "suck", it's high pressure pushing. So Neko Jeff is technically
> wrong but in practical terms he is right.

I never said that low pressure sucks. That is what Bryce suggested above. I
said that the wind doesn't push the boat. You're right that it is high
pressure air pushing under the airfoil, which is not fully countered by the
lower air pressure above the air foil, that moves the boat. But that is a
force that is (roughly) at a right angle to the direction of the wind. So
when I say the "wind" isn't pushing the boat I am not only practically
right, I am technically right. The movement of the wind above and below the
airfoil merely creates the pressure differential through a phenomenon known
as Bernoulli's Principle. The wind itself doesn't do the pushing.

And for the sake of completeness, there are times (such as when you want to
go exactly in the direction of the wind) that you might let the sail out at
a full right angle to the boat and allow the wind to push you, but it is by
using Bernoulli's Principle and treating the sail as an airfoil that you can
get the greatest speed in a sailboat.