Two Questions

[Skip Garr]

1 Can a sailing ship move faster than the speed of the wind?
2 I have heard that sails act as an airfoil so that the sails are actually pulling the ship rather than pushing it. Is that true?

 

[Dave Stevens (Lumberyard)]

1 Can a sailing ship move faster than the speed of the wind?

yes

 

[DARIVS ARCHITECTVS]

The horizontal "lift" force of the sail acting as an airfoil is called "apparent wind".

 

[kuba91nt]

1. Air current and sea current are different things, they act independently. Yes.
2. The wind pulls. The wind creates a forward aerodynamic force and creates ''aerodynamic thrust''. At least that's what they taught me.

 

[Uwek]

But I guess not the normal frigates, sloops and ships of the line were faster than the wind......

 

[Skip Garr]

Thanks to all for your information.

 

[Corsair]

Some people understand better with pictures.

 

[WDO]

The principle of the airfoil works by curving the wind. The side facing the wind is a straight line, while the outer side is curved. That means that on the outer side the speed must increase as it has a longer distance to travel. This then creates a vacuum (slightly lower) pressure on the outer side, thus the term pulling along. Same principle as on an airplane, it is sucked up into the sky.

 

[Signet]

Racing airfoil catamarans can sail over twice the current wind speed (not in the same direction, of course). See article How SailGP’s foiling F50 catamarans sail so much faster than the wind. A current, sleek sailboat has a theoretical maximum practical speed of SquareRoot(Length)x1.34, or 9.5 knots for a 50 foot long boat. Increased friction gets too high when this value is exceeded, even with higher wind. Hulls of tall ships as we know and build them are much slower (clippers and such excepted, of course).

 

[Thomas]

An old sailor once told me that the combined effect of the wind and the sails made the ship "like a watermelon seed you squeeze between your fingers." I think that's what he was talking about!

 

[bill36]

1 Can a sailing ship move faster than the speed of the wind?
2 I have heard that sails act as an airfoil so that the sails are actually pulling the ship rather than pushing it. Is that true?

1. Yes! It is simple geometry and physics.
2. Any six year old racing sabots (a six foot catboat) on the coast of New England is an expert in this subject.
3. You can't get a sailboat to move an inch without proficiency in this subject.