In the construction of hollow boards, or any craft for that matter, how is the strength requirement calculated? For example:if you were to build a totally hollow glass board (Like the old wave skis) you would need a certain weight of glass as there is no structure within adding support. At the other extreme, a board shaped out of a solid piece of cedar wouldn’t need any glass at all. This issue not only influences glass weight choice but also ribs or framework per square foot in the hollow wooden board. Is this a definite science or a combination of trial and error and experience?
…I’ll leave the final word to the scientists…I’m a trial and error guy… …Since July of ’02 I’ve built four hollow wood surfboards…Here’s what I’ve found… …The interior ribs and stringer don’t do much structurally…They hold the shape and the stringer does keep the deck from collapsing…The ribs only keep the deck and bottom in place until the rails are on…The primary strength is in the rails…An underlying layer of 1/8” lauan plywood stiffens the deck nicely…A lightweight might not need it, but my 200# feel better standing on something stiff…The bottom can be light and still be strong…Glassing holds it all together, and keeps the dry from getting wet…Quality glassing is a very good thing…Epoxy resins are a must with wood…Do it right… …My web-site has more about “How To”, and my current board has some new ideas, check out the “New” page… …I’m happy to answer any non-scientific questions… Paul http://www.hollowsurfboards.com 
Paul J. i like your fin that Paul Gross suggested to make. some unreal ideas and craftsmanship coming out. do you have any in production, or still messing around with ideas? what’s the advantage of a wider based fin?
Thanks Paul. Your website is brilliant. I figured most of what is incorporated in board design started out as trial and error. someone somewhere made one so light it fell apart then built up from there. The beauty of forums like this one and websites like yours is that the trial and error has a much wider base than could be accomplished by anyone individual. we learn from each others successes and mistakes.
I have seen hollow boards worked at for over thirty years and I have some thoughts. There are a number of disadvantages to hollow boards that are to be sold to the general public. 1. As Paul said above, the stringers don’t add a significant strength value and do add weight. 2. Since there isn’t and dampening component, (like foam) anytime the board is impacted the force goes straight to the weak point of your composite structure. Stress at that weak point over time causes a failure at that point which usually manifests itself in a cracked rail. 3. Most molded boards today use a foam interior of 1# EPS. The hollow boards built in the past and experimented with in the recent past by the European sailboard industry found that an interior structure actually weighed more than 1# EPS and didn’t have the dampening effect the foam does. Further the EPS foam actually added more structural support than the stantions. 4. Unabated leaking. Although you can easily drain a hollow, if there is any breech in the skin they do take on water at an amazing rate. This makes immediate ding repair a must. In my veiw we have already past the day when the hollow board is something futuristic. I’ve even seen balsa boards with EPS cores. With the kind of money spent in recent years on r & d in the sailboard industry and their rejection of hollow concepts it’s doubtful that technology of this type is valid.
I still haven’t seen one in person… Hollow Carbon Fiber Bisect. I wonder if they’ve worked everything out?
Its all about a game known as point loading, and how to design an adequate strength vs. weight ratio for each boards needs. As a hollow surfcraft builder works toward the low end of strength and weight in a surfcrafts structure, the overall stress applied while surfing will automatically find an area in the board to focus, the result being fatigue, cracking and/or complete failure... the same things that occur every day in most all conventional surfboards. This subtle, but progressive break down in a boards structure may not be visible or even felt until such time as serious damage occurs. But if a hollow builder is aware of his surfcrafts limitations, and orchestrates materials and design in a proper manner, the problems of point loading under normal use can be eliminated. Although such hollow wood boards (built using conventional means) may be slightly heavier, they will offer unique dampening characteristics as well as resonant sensitivity and the buoyancy of a comparably thicker conventional foam/glass board. A simple method of designing/building for adequate strength vs. weight is through trial and error. Establish a boards low end failure point and then just build up slightly, either using more conventional materials, or reinforce and/or substitute them with modern high tech composites which offer significantly higher strength to weight ratios. Hollow surfcraft have a long, rich history, and while they may not be for everyone, for a few they are a satisfying, legitimate means of riding waves… and will undoubtedly continue to play a part in the future of surfing.
I hope you understand that the comments I made above were about building boards for the general public. Hollow boards do have their niche and offer a different experience than standard fare.
Yes I agree, Greg. In some ways, the differences between commercially manufactured, and personally handcrafted hollow and conventional surfcraft are much like trying to compare bananas and raspberry jam. So many things can work great when created, used and maintained on an individual level, but would be hell on wheels if sold to the general public. Dale
I agree with most of what Dale and Greg have said… As far as the general public getting on a non-conventional board…I can’t see it…Their overall board sophistication goes as far as the label on it…And the bottom line to most is the cost… What I’m doing is for me…I’m just following my curiosity…I’m so excited about the discovery process and the wide horizon of potentialities that I can see… With the foam thing, it seems to me just a circular design process…Sure the foams change, but the basic medium has been so refined that to me it seems stagnant… I know I’m way outside the box on this one, and I’m not putting anyone down for what they do…Really…I’ve just headeding down a different path… Paul Sorry, if I stepped on someones toes… http://www.hollowsurfboards.com
Paul, The medium of foam is not the problem. The problem many times lies in creativity or lack thereof. Foam should be a shapers dream of unlimited possibilities and yet today terms like overshaping, density gradient, and close tolerence have painted shapers into very constricted corners of design. The freedom to make and to later understand true design creativity are not presently available to ALL shapers. These freedoms are today only allowed to be exersized by a select chosen few. Is it any wonder that the original squashtail 3 fin has changed as little as it has in the last 22 years.
If I`m going to be shaping something out of foam, give me a rockerless, stringerless, over-sized, rectangular, white slab with consistent density throughout. Maximum creative freedom. I get really excited looking at a blank canvas, but not paint by number.
Paint by number blanks. One of my favorite terms! I do start with square slabs, much more interesting and challenging. Your one of few who see that shaping from the ground up is the only way the design is really YOUR OWN.
Greg, Within surfing, there should be more latitude for both production-oriented pre-shapes and over-size, consistent density, stringerless, rectangular foam planks. What some shapers consider restrictively wasteful, inefficient and time-consuming… is to others, the very means by which they achieve full creative license. In terms of personal satisfaction, there is no parallel in sculpture like clearly visualizing a complex, finished form before it ever exists, and then accurately releasing it from the confines of an unfinshed, over-sized mass. Down through the centuries it`s been observed that the highest levels of human endeavor are best given life when they first arise from out of… nothing. Fortunately, some things never change.
“In terms of personal satisfaction, there is no parallel in sculpture like clearly visualizing a complex, finished form before it ever exists, and then accurately releasing it from the confines of an unfinshed, over-sized mass. Down through the centuries it`s been observed that the highest levels of human endeavor are best given life when they first arise from out of… nothing.” …Dale you said it perfectly…again… …To me, there is no creative process that can achieve the personal satisfaction of starting a project with just an idea, and proceeding to create, from scratch, a complex, functional, and artistic medium to enjoy uncrowded waves… Paul http://www.hollowsurfboards.com/new.htm 
Dale and Paul, I couldn’t have said it better, especially the personal satisfaction angle. I look at Clark’s catalogue and they produce, maybe, two or three new plugs a year. I do 10 or 12 just for me. I shaped that old way for along time and even when I designed plugs, after a few months I always found myself altering them. In other words they begin to become obsolete almost from the time their produced. Today I just make a new rocker template and cut some new blanks. Much better creatively and much more accurate than doing the mow. And like you said above, satisfying.
Paul, As you well know… whether hollow wood board or surf mat, such structures are unique and far more complex in that the process of their creation not only involves shaping the outside, but also the inside… literally forming something around nothing.
Why wouldn`t a girl want to put something that sexy between her legs? Your hollow wood boards are simply gorgeous beyond belief!
I’ll admit it… looking at Paul’s stick gives me wood.