Measuring the volume of a clubhead can be one of two ways. The easy method is to take a beaker of water that has a wide enough opening for the head and fill the water to a specific level, like 1000cc or 1500cc to make it easy to figure out the displacement of water. Make sure that once the clubhead is placed into the water that the head can be fully submerged and that the water will not overflow the beaker.

Next, submerge the head up to the base of the hosel (if one exists) as the hosel is not considered part of the volume of the head. The water will rise inside the beaker as the clubhead displaces the water. Take note of the new volume in the beaker as you will subtract the starting amount of water inside the beaker from that measurement. Let’s say the original amount of water inside the beaker was 1500cc. If the club was submerged up to the base of the hosel and the new displacement became 1950cc, this means the volume of the head is 450cc.

The problem with this method is most beakers do not have enough gradients to be perfectly accurate as each gradient on the side of the beaker that would be wide enough to except a driver head may be in 50cc intervals. The maximum volume of a golf club, according to the Rules of Golf, is 460cc (+10cc tolerance) or 28.06 cubic inches, so there can be some interpretation as to the true volume of the head. This leads us to the next method, which is not all that much different other than it requires a weight scale.

The use of water to make a volumetric measurement make it easy as 1 cubic centimeter (cc) equals 1 gram of water. Set the beaker of water on an accurate scale and do the exact same method as above by submerging the head. Instead of looking at the volume displacement by reading gradients on the beaker, now we will look at the change of weight on the scale. Some electronic scales have a tare button which will zero out the weight on the scale. All you have to do is submerge the head, steady it, then read the new gram weight on the scale. If the weight is 453g, then the volume will be 453cc.

Now that we have established the different methods of measuring volume, we will look at the importance from a design standpoint. Since the USGA and the R&A of St. Andrews established a volume limit on the head, every manufacturer is making drivers that go up to this size limit. There are also a few other restrictions in the Rules of Golf that apply to the size of a driver. These are the following from Appendix II. 4. Clubhead, b. Dimension and Size:

1. The distance from the heel to toe of the clubhead is greater than the distance from the face to the back;

2. The distance from the heel to the toe of the clubhead is not greater than 5 inches (127mm); and

3. The distance from the sole to the crown of the clubhead is not greater than 2.8 inches (71.12mm).

The way to think about this is the maximum size a golf club can be would be if you were to imagine a solid block with the dimensions 5 inches (12.7cm) long by 5 inches (12.7cm) wide by 2.8 inches (7.112cm) tall. If we were to place this solid block in a beaker, it would displace 70 cubic inches or 1147 cubic centimeters or 2.5 times the amount of the maximum sized driver!

If you closely examine a clubhead, you will notice all the angles, contours and rounded corners. These in effect limit the volume as illustrated below.

The white shadow of the head is laid over a square with the maximum dimensions of the head in the corresponding plane where as the grey areas are what is cut out. Note that the hosel is omitted from the basic block as it is not part of the volume measurement. To make this or any driver conform, a lot of material must be removed in order to achieve 460cc.

Using the Rules of Golf limits on size, let’s examine what will happen when we create certain dimensions. In our case, we will use simple rectangular blocks to demonstrate some important ideas. If we want to have as broad and long of a club as possible, then the maximum the clubhead could be is our 5" by 5" base. If we wanted a 460cc volume (28.05 in^3), then the maximum height could only be 1.12” (2.85cm) tall. Obviously this is much shallower than a typical driver which is roughly half the dimension to the top of the crown of a modern 460cc driver. Assuming the solid block was made from the same material throughout, this would mean that the block would have a center of gravity that would be both low and rearward from the striking surface.

In the other case of the maximum limits using face height, the face plane would measure 5" wide by 2.8" tall. If we wanted to create the same 460cc volume (28.05 in^3), then the maximum width could only be 2” (5.09cm) wide. This would be dramatically narrower than modern 460cc titanium driver by half again. This time though, this block would exhibit a center of gravity that would be very high and close to the hitting surface.

Although these extreme examples were used, it does show that there are cause and effect relationships with designing a golf club. If the designer wants to make a 460cc titanium driver that is broad from face to back, then the heel-to-toe dimension might have to be shortened, crown height reduced or the crown may have to be flatter or more rounded corners on the edges to stay within the limits on size.

If a new square shape does become popular like our new Acer Mantara driver (see below), then remember more material will be in the corner area of the block, therefore the other dimensions from top to bottom or from heel to toe will have to be scaled back some and create a slightly smaller footprint at address.

Hopefully you have a better understanding of what clubhead designers have to go through to develop new models with the limitation imposed by our governing bodies. Now use your imagination and chisel your way around that 1147cc block to create the next new driver on the market!

by Jeff Summitt
Hireko Technical Director
jsummitt@hirekogolf.com