Naked Science Forum

General Science => General Science => Topic started by: @Alex70666 on 27/11/2011 15:01:02

Title: Why don't sailing boats tip over in a strong wind?
Post by: @Alex70666 on 27/11/2011 15:01:02
@Alex70666 asked the Naked Scientists:
   
How do sailing boats not tip over in strong wind?

What do you think?
Title: Why don't sailing boats tip over in a strong wind?
Post by: RD on 27/11/2011 15:08:45
a keeler application (https://en.wikipedia.org/wiki/Killer_application) (groan) ... https://en.wikipedia.org/wiki/Keel#Hydrodynamic_keels (https://en.wikipedia.org/wiki/Keel#Hydrodynamic_keels)
Title: Why don't sailing boats tip over in a strong wind?
Post by: Bored chemist on 27/11/2011 15:25:10
They sometimes do. Here's someone nearly proving this.
http://en.wikipedia.org/wiki/File:Aus2.jpg
Title: Why don't sailing boats tip over in a strong wind?
Post by: CliffordK on 29/11/2011 09:00:51
Many keels are full of LEAD as a heavy counterweight, although some newer boats just use water ballast tanks as low as possible in the water.

Also, keep in mind that in modern sailing boats, one can alter the direction of the sails to capture the optimal amount of wind...  without catching too much.

If the wind is coming from behind the boats, then one would have the sails out at a 90 degree angle to pick up the wind to push it forward.

If the wind is coming to the side, then one has the sail at a 45° angle to push the boat forward.

See Wikipedia Points of Sail (http://en.wikipedia.org/wiki/Points_of_sail)

In many cases, The crew acts as ballast to help keep the boat upright (http://i48.tinypic.com/s2hdex.jpg).
Title: Why don't sailing boats tip over in a strong wind?
Post by: LetoII on 05/12/2011 00:21:16
me and some buddies were @ the beach a couple of years ago and i had my eyes on this sailing boat. it was katamaran like i believe. Anyway, i noticed that in its zigzgging course its tip started to get closer to the water with each turn so i told my buddies like if that goes on 2-3 times it'll hit the water and capsize. it turned 2-3 times and there it went, into the water. it was funny to watch tbh.
it was however not stationairy
Title: Why don't sailing boats tip over in a strong wind?
Post by: Mazurka on 05/12/2011 12:18:02
I am curious as to the development of keels.  Many historic sailing boat designs do not appear to have a keel (apart from the structural keel around which it is built)
or put another way
Why did HMS Victory not keel over given the surface area of sail involved?
Title: Why don't sailing boats tip over in a strong wind?
Post by: CliffordK on 05/12/2011 12:33:56
Quote from: Mazurka on 05/12/2011 12:18:02
Why did HMS Victory not keel over given the surface area of sail involved?

Have you read about the Vasa (http://en.wikipedia.org/wiki/Vasa_(ship))?

I believe that most of the square mast ships keep their sails more or less perpendicular to the keel.  And, they take their primary wind vector from behind.  A cross wind would just flap the sails in the wind.

The triangular sailed ships can capture power from a cross wind, and in fact can go faster with a cross wind than a tailwind.  But they require a keel to keep the from sliding sideways in a cross wind, and ballast to keep them upright. 

Or..  the cameraman (or multi-hulled boats) can spread the force of the sail to the outrigger.

As was mentioned above, nothing is foolproof.