Why are headsails traingular?

Question

This is for a geom. homework. Why is it triangle? What's the significance of it being triangle?

Answer 1

Headsails are the ones at the top of the mast, no? Most contemporary rigs don't use these.

Jibs are the sails in FRONT of the mast and are triangular. Why are they this shape? Well, the luff of the jib attaches to the forestay via some plastic or metal clips. What the jib does is it speeds up the air running behind the mainsail before it comes into contact with the mainsail and provides better efficiencies for the mainsail. You know what faster air means, right? Do you need me to get into Bernouli here? That is what is happening here.

In my tiny opinion, Joe T doesn't know squat about aerodynamics. *laughter*

Answer 2

The wind acts upon the surface area of the sail; the more surface area the more push given by the wind. The more push generated, the greater the need for a strong mast to hold the sail in place. If a square or rectanguar sail is use, a cross-arm is needed to hold the mounting points.

1. Using a square or rectangular sail calls for a mast that is much heavier adding weight to the craft
2. Same with using a cross-arm.

With a triangular sail the majority of the force is at the bottom of the sail, so the mast can be tapered and thus weigh less plus there is no cross-arm.

The overall effect is that the closer to the craft's waterline the force is concentrated, the greater the effect the force will have in pushing the craft forward against the resistance of the water.

Dunno how this translates into your homework, but that's the reasoning behind triangular sails.

Answer 3

It is seldom that the wind is blowing in the same direction that you want to travel. Every sail, therefore, produces a force perpendicular to your line of travel. This force causes a torsional moment that makes the boat lean in a direction away from the wind, or tries to tip the boat over. The torsional moment is equal to the force on the sail times the moment arm. The moment arm is the distance from the surface of the water to the geometric center of the sail. You can minimize the moment arm by using a geometrical shape of your sail that has the lowest possible geometric center. That's why triangular sails are used. They have a low geometric center.

Answer 4

I'm no sailor or anything. But I do know quite a bit about aerodynamics. I mean, the head sail would need less surface area due to the fact that there are other sails pushing the ship forward. If it was square, the resistant wind would have more surface area to push against, making the sail useless. Although, that is all just a guess, it seems to make sense to me. Hopefully, that made sense for you too. =D

Answer 5

They are not.
Sails inflate to semi-spheres and are not triangles. Simply semi-spheres held at 3 points in the case of a jib.

Sails are held at three points simply because a forth point is not convenient. Any time a sail can be held by a 4rth point it is. 4 point sales require a boom aloft. and complicate rotating the sail. For and aft sails with 3 points are easy to rotate with the lower boom.

Large sail inflation's high aloft can raise the center of sail wind mass to high for some keels.