# Spin in Ice Hockey Shots?

Spin is highly important in professional ball games such as tennis, football (soccer) and basketball. In order to shoot with spin in tennis, you need to have enough flexible hands/arms and learn the proper technique. Spin also helps to score in basketball because side-spinned balls turn more easily to the goal. In football (soccer), spinned shots are highly unpredictable for the goalkeeper and defence, making scoring more probable with the surprise element. Golf balls can travel father away due to spin. Spins are everywhere and its understanding can be a real advantage!

The importance of spin in ball games make me wonder whether spin is also used in ice hockey or could it be used? I feel topspin and backspin are very rare in hockey. So

• How is spin done in ice hockey?

• What kind of spins are they?

• Side-spins? And when are they used? Do they deflect the puck in the air?

-

A hockey puck is a very flat cylinder. We may compute very easily the Moment of Inertia of a hockey puck in both the axis of symmetry (going through the center of the puck from top to bottom) and the central axis (going through the sides of the puck) quite easily.

The moment of inertia around the axis of symmetry is 27 square inch square ounces, while moment of inertia around the central axis is 28.5 inch square ounces. These quantities are not vastly different, and if you grab a hockey puck, it's about as easy to flip as it is to spin.

The difference, however, is that a hockey puck's stable attitude is going to be laying flat. As such, most of the time when you play with the puck, it's going to tend to lay flat on the ice.

It's not hard to flip a puck end-over-end, but unlike the aerodynamics of a ball, a hockey puck has relatively large flat surfaces. This makes controlling the puck in such a way very difficult, and it's quite hard to shoot a puck if it's not laying flat. Due to the motion of a shot and the geometry of a stick blade, shooting a puck on-edge makes it much more prone to go high, and it's hard to control the accuracy. In addition, it's much harder to shoot the puck with any high velocity, as the puck doesn't sit well in the blade of the stick.

Like a football, a puck flipping end-over-end will bounce unpredictably. Occasionally, players will attempt to surprise a goalie by flipping the puck to try to get a lucky bounce, and even in the pros, it happens a few times a year that a goalie lets one by.

However, flipping the puck at the goalie like this is a low-probability play, and it is one that is nearly guaranteed to result in a change of possession. Consequently, it's rarely done.

It's much better to try to shoot the puck hard and accurate in order to beat the goalie in a spot where they're not expected to make a save.

In this case, the spin of the puck actually does very little in terms of its dynamics. The puck is too heavy and the flight times are too short for the Magnus Effect to have much of an impact on the puck's trajectory, and the moments of inertia being so close in value mean that the rotational effect does very little to stabilize the puck. The spin is a consequence of the shot mechanics -- stick blades are curved to give the player control over the puck while handling it and shooting it, not to induce spin.

The pace of hockey is extremely fast. Any deception is better suited by using your other players (e.g. fake a shot and pass to an open player with a better view of the net) than attempting to play trickery with a shot. Even a 65 mph shot, which is fairly slow, especially for the pros, will travel 25 feet in about a quarter of a second. Speed and accuracy, not deception, are the shooter's best friend.

-

First, in hockey the blade is curved. This will lead to the puck spinning clock wise or counter clock wise depending on if the player is right or left handed, and if the shot was taken with the front or back of the stick.

There are often times where the puck will have top spin or back spin. These are not always intentional, as hockey is a fast paced game played in a relatively small area. Players will mishit the puck or it may get deflected by a defender. Also with the goalie wearing pads and taking up a significant portion of the net, the top spin or back spin may just hit the goalie. The tight side spin will allow for more control and velocity of the shot into the open areas of the net.

You can often see defensemen flip the puck out of the defensive zone with some top spin to avoid icing the puck, but in order to clear the defensive zone.

The deception that you refer to in other sports is created in hockey mostly by screening the goalie and deflecting pucks. The player in front of the net will try and get in between the goalies line of sight with the puck. He may also try and tip the puck in mid air with his body or stick. These deflections make the shot unpredictable to the goalie.

Here is a link of a tip in

Here is a link of a goalie screen

-
+1 excellent points from the first reference: `"Spinning gives the puck more stability"`, `"A blade that tips backward is said to be more “open faced”, very much like a 9 iron is compared to a 3 iron in golf."` -- golf/tennis really helps to understand elements in other sports! I personally use more curved blade precisely because it makes control far easier and a surprise element with fast upshot. Yes and does the spin add deflection to the shot? Does the spin make the puck deflect in the air or is the flight path totally straight? – hhh May 15 '14 at 19:21
@hhh Spin shouldn't add or decrease effectiveness of a deflection. Usually it is just good hand eye coordination by the deflector to get a piece of the puck and change its direction. Without being to scienftific... the puck is pretty low friction, but something rotating in a direction would cause it to move in that direction due to changes in air pressure created. This can be seen by a curveball in baseball or a top spin or slice shot in tennis. – diggers3 May 16 '14 at 21:33
@hhh players usually want stability on their shots because they are shooting at a certain area. If they didn't want stability and want to incorporate some randomness or instability, then they would turn to a more flat stick blade. This is seen more with defensemen who shoot from a distance with slap shots more than with precise wrist shots. – diggers3 May 16 '14 at 21:38
@edmastermind29 I think of it more in relation to baseball. The puck is flat on the top and bottom which changes things slightly. This talks about how a curveball works. Also the gear effect has to do with the way the clubs work in golf. The golf ball rolls into the center from an edge to create spin. I believe if you had a completely flat stick with a "softer" center than edges then the gear effect could come into play. – diggers3 May 20 '14 at 20:26
@edmastermind29 However sticks are curved and a wrist shot will spin off the blade as in the link in the answer. A slap shot may spin off or "knuckle" depending on how it is struck. The aerodynamic properties then take over in flight and the puck will move according to the angular velocity and air density. Realize that it is a short distance a shot travels, as well as with pretty good velocity so the air displacement may not move the puck too much. I cant see a scenario where it would spin the opposite direction. – diggers3 May 20 '14 at 20:30