Archive for March, 2009

Dimpled surfboards?

March 29, 2009

Let me add a bit more on speed and I’ll move on. Many of us love to ride those classic “A-frame” peaks. Well, I doubt if you’ll be happy riding a fast (low-drag) surfboard on those peaks. You will outrun the wave and won’t get much of a ride. For that type of wave I’d suggest a bit more lift in the tail and somewhat rounder (or softer) rails. The board will hold back in the pocket better and turns will be tighter. You will have more fun and you will look better too.


We live in a highly technical society, but many of us know little about the most basic scientific relationships. Even though I might be inclined to class surfing as an art form; the board that we ride responds to the water and wave according to the laws of physics. While you don’t need to know physics to be a top surfer, and while many shapers who are good craftsmen, don’t seem to have a good grasp of the physics involved; understanding basic (high-school level) physics can expand your understanding dramatically. I continually see claims for surfboards, that are a bit off the mark technically, and that is why I mentioned earlier that I shifted to reading windsurfing mags.


Let me point out that the best surfboard is the one a surfer likes the best and if he thinks his slow surfboard is fast, that’s true for him, but it doesn’t help us learn how to make a faster surfboard. This is also true of every aspect of a surfboard, such as how well it turns, how well it trims, how well it accelerates, etc. Many of us try to borrow ideas from other sources, without understanding the basic science involved, and we often come up short.


A few years ago I heard of someone who tried putting dimples on the bottom of his surfboard to make it faster. We all know that a golf ball is dimpled; how many of us know why? A dimpled golf ball has less drag than a smooth ball, so it goes much farther when hit. At first glance it might look like dimpling our surfboard would make it go faster, but if we try it, we find out it makes our board slower. If we examine the fluid dynamics of a golf ball a bit, we discover that below 125 mph a smooth golf ball has less drag than a dimpled one and above 125 mph the dimpled ball has way less drag than the smooth one. Well there is a big speed difference between a golf ball driven off the tee and a surfboard. We also note that water is a whole lot denser than air (about 800 times denser). Additionally, a golf ball is round and it flies through the air, whereas the bottom of a surfboard is not round and it slides along the top of the water. Every one of these points is a factor in why a dimpled surfboard is slower, but a dimpled golf ball is faster.


I’m not saying we shouldn’t try experiments like dimpled surfboards; we should if it helps our understanding, but we also need to find out why it works or doesn’t work. The more we understand about water and waves, the more we understand about the surfboard and how it interacts with the water and wave, the better we’ll be able to envision new possibilities in surfboard design and new ways to ride the wave. One of the reasons I wrote “The Basics of Surfboard Design” is to help expand our understanding of the surfboard so we can make better surfboards.




Slow or fast?

March 24, 2009

Last post I told you one situation where a slower board can be superior to a faster board. But since most of us claim we want to go faster, can we go really fast and still have fun? Here’s another story.


My good surfing buddy (C-MAC) dragged me off to a surfing camp a few years ago. We had a great time; warm water and waves to surf every day. There was, however, one problem; the camp surf guide was guiding us away from the best waves!


When we first got to the camp we were shown a sketched map of the area with the surfspots marked. The spot in question was called “Leftovers” and was described as a slow mushy wave, which wasn’t quite true. The camp had some potentially good spots right in front, but while we were there, they never got big enough to ride. As a result we went by boat to a tiny island that had several spots including Leftovers. Our approach to the island was always from the south end, (the swell direction was from the south also) but Leftovers was on the northwest end of the island, putting it towards the lee with respect to the swell, so we didn’t give it a second thought. We got dropped off at some of the breaks, but our guide remained with the boat operator (a local who didn’t surf) and they drifted off. At first glance this was fine, because the staff of a surf camp should never surf with you, unless you request that they do.


Towards the end of our week’s stay, the surf had increased a bit and we asked to approach the island from the north end. We approached from the tail end of Leftovers and motored up the point to the start of the wave. It looked pretty good and the surf was about 6 – 8’. We hopped out and I paddled over to what looked like the take-off spot I wanted. Immediately our surf guide paddled over and told me I was too far over and the wave couldn’t be made from that deep. I shrugged and replied that it looked ok to me.


Let me add some info here; our guide appeared to be in his late 20’s and was surfing regularly, he was riding a typical tri-fin short board. I was in my mid 50’s and hadn’t been surfing much due to other commitments, so I was out of surfing shape, but trim. I was riding a 6’ 6” down-railed, hard-edged, rocket I’d made.


Well, even though our surf guide had been burning us, I got the last laugh. I made most of the waves I caught from way deep. Seeing this, our surf guide tried to take off deep, but he got cleaned out every time. Even though he had a big advantage in strength and conditioning, I had a vastly superior surfboard for the wave we were riding. In this case faster was better and made the difference between a great ride and a wipeout.



Fast or slow?

March 24, 2009

In my book on surfboard design, I have a chapter titled “Speed”, in which I discuss how the design affects speed. From what I’ve heard and read, most surfers seem interested in going faster, and there’s no question that the better surfers today are going much faster than anyone was when I started surfing. This is due partly to an advance in board design and partly to an advance in skill level. However, even though most talk about going fast, it has been my observation that most don’t seem to want to go really fast. This is an interesting contradiction; let’s see if we can understand it.


We observe that young people are faster than old people, and most of us would rather be young than old. We also notice that our society keeps speeding up (from walking, to horses, to cars, to jets, to rockets) so it’s easy to see why most of us would want to go faster. But for surfing, is faster better?


Here’s an experience I had that will provide more data. I had been experimenting with fast (low drag) surfboards for a few years and one day I was at a beach-break, but the surf was small and the wind was onshore. Now I don’t usually go out when the waves are bumpy, but there was no one around except a couple of friends, so I took my trusty, 5’ 10” down-rail, hard-edge, rocket out and made a fool of myself. I couldn’t do anything right, I felt like the ultimate kook! I retreated, in humiliation and disgust. However, I happened to have a surfboard with me that I had made for my girlfriend. It was quite similar in size (6’) and shape except, I had purposely “detuned” it by rounding the rails some in order to slow it so she would be able to ride it. I believe I had only ridden that board once before (at night) so I had little experience riding it. I paddled out and started riding, the difference was huge, I could do nothing wrong and went from total kook to champ by changing from a fast to a slower surfboard.


Why was that? Here it is; the fast board slammed into the chop and lumps on the wave and all control was lost. On the other hand, the slower board moved along the wave in harmony with the dips and lumps; it was perfect. I was astounded at the difference between the two.


Is faster better? Not under those conditions! You will want to select your board based on the waves you will be riding and the way in which you wish to ride them.



True or false? — Take a look

March 20, 2009

I want to point out something that is a key part of my approach to understanding anything. Do not automatically believe what someone tells you or what you read. When you hear or read something, be sure you understand the words used and then the concept being communicated. Now that you have the concept, you must determine if it is true for you. In my last post I stated where the sand was on the North Shore in summer and in winter; the best way to find out for yourself would, of course, be to go and look. However, that might not be practical, but perhaps there is a sand beach near you that gets fairly large waves at times. Find out what happens to the sand at that beach and you will discover how the waves and sand interact.


Beware also of the same false idea being stated by more than one person or publication. The false mag statement I exposed in my last post has been repeated in a recently published book. There is a good chance the book’s author read the earlier article and didn’t find out for himself if it was true or not and simply repeated it. The number of times a false statement is made does not make it any less false. Find out if it is true for you.


The Basics of Surfboard Design” is a description of what I learned from making surfboards. I did not learn it from anyone or from any publication. I did look at what others were shaping, and if it looked like it might have promise, I made my own version. Each time I tried something, I attempted to understand why it worked or why it didn’t work. Note that you can often learn more from your failures than from your successes, providing you move forward from any failure. I believe my book describes all the elements of the surfboard shape and how these elements affect the ride. Of course there’s only one way to find out – take a look!



Wishful thinking

March 19, 2009

Aside from writing my book on surfboard design for myself, I wrote it for anyone interested in surfing because I have not seen a good description of how a surfboard works. Most of the tech articles I’ve seen in the surf mags have been little more than wishful thinking, although there have been a few shapers who did say some intelligent things. This was so bad, that in the 80’s I started reading windsurfing mags because the tech articles were vastly superior to anything published in the surf mags. Now realize that I have never gone windsurfing, even though some of my surfing friends took up the sport, raved about it, and encouraged me to join them. I knew that if I started windsurfing, I would be building my own equipment and I didn’t want to do that; I was already developing an exotic high-speed sailboat:


An example of the “wishful thinking” I mentioned is: some years back one of the surf mags ran an article about the North Shore of Oahu. This article explained how in the summer (when the waves are small) the sand covered the reefs, but in the winter, the large waves swept the reefs clear of the sand and the waves got good. This is totally false; it’s exactly backwards! It makes one wonder if the author or mag editors had ever been to the North Shore. One starts to wonder what they had been smoking.


What actually happens is that in the summer, the sand is all piled up on the beach and in the winter, the large waves pull the sand off the beach and into the surf zone (filling in the reefs and making sandbars). But don’t take my word for it (or the mags fantasy) go look! This same phenomena is true of any sand beach that gets waves. It’s not necessarily a summer/winter event but rather a large wave/small wave event. The best description of this (including how and why) is found in Willard Bascom’s book “Waves and Beaches”. Every serious surfer or beach lover should own a copy of this book.



Bob Smith Surfs – intro

March 17, 2009

Greetings to the surfing world; let me introduce myself: My “real” name is Bob Imhoff but my surfing “stage” name is Bob Smith, also my surf related pen name is Bob Smith or Bob’s Myth. There is no reason for this except it’s fun.


I decided to write this blog to expand on the book I wrote, titled “The Basics of Surfboard Design” as well as to discuss making surfspots and answer questions. You can find the book by visiting my website at:


First let me explain why I wrote The Basics of Surfboard Design. I started surfing about 1960, began making surfboards in the mid 60’s and got “serious” about making surfboards in late 1967 on the North Shore of Hawaii. My main interest in making surfboards was “experimental”; I was always trying to learn how to make a surfboard do exactly what I wanted it to do. During the late 60’s and early 70’s I did make surfboards for others, but I was never a production shaper and I only worked for myself. I was one of those “backyard” shapers that the surfing mags warn you not to patronize or “bad stuffs will befall you”! What that means is; I wasn’t buying advertising in their mags nor hanging with the big names; I didn’t need to, I had so many guys asking me for surfboards that it started cutting into my surfing time. As a result, I stopped making boards for anyone except a few friends. When I say make a surfboard I mean shape it, glass it, make the fins, and I even make my own design fin box.


In 1976 I decided I should write down what I had learned about surfboard design in order to keep that from getting lost. This was extremely beneficial to me because it forced me to examine what I had been doing and resulted in a better, more complete and more basic understanding of how a surfboard works. However, my understanding of the surfboard was incomplete at that time and the manuscript got filed. I eventually learned the rest of the basics and finally completed and published the book.