'Building the Dragon Board' article by Roy Stuart from Australian Amateur Boatbuilder magazine.

by: Roy Stuart as featured in the Australian Amateur Boatbuilder 2004



Riding a huge timber surfboard is a great way to surf. The pilot of an Olo longboard is able to open up virgin territory and ride previously unsurfable breaks. Even normally crowded surf spots can provide epic solo sessions in conditions which are outside the range of normal surfing equipment.



A really big board like the olo is able to connect scattered breaking wave sections together so efficiently that surf which appears to  irregular or blown out, often proves to be easily cruisable.



Gliding on big unbroken swells is another relaxing pastime, and if the craft well designed it can also slot into hollow waves when they occur:

Shown here is the 13'9" Dragonboard, part of a quiver which includes a 12' and a  17' model. All three of these boards have proven themselves over the years to be capable of riding just about any wave that comes along.



The extreme pintail design is usually associated with paddle boards, but is really he best possible tail shape for an Olo. By providing the most planshape curve over the longest distance , the circular arc rail line of the extreme pintail allows better manoeverability than a board with a more parallel outline. These boards are ridden from the middle of the board without walking up and down.

Early hollow plywood boards built in Australia show similar planshapes to the Dragonboard.

The Dragon differs in that it has more rocker curve, a much more substantial fin, a lower centre of gravity, a round rail, and fore and aft flexibility.

By departing from the usual system of fore and aft taper (viewing the board from the side), in favour of a parallel profile, the board gains a swooping deck curve which exactly matches the bottom curve, giving a lower riding position and far better control than the ponderously thick,  flat decked  types.



Construction wise the machine is a simple four layered  'sandwich' built over a mould.



The plans shown here have been developed from the original Roy Stuart balsa pp system to allow the boards to be built from heavier timbers. Using a double diagonal internal layer torsion box construction  we get a strong flexible hollow structure. Plywood can be substituted for the fore and aft planking on the deck and bottom if a more tradtional look is desired.



Unlike foam or balsawood surfboards, with a board built from a harder timber ( Redwood, Cedar, lightweight pine and Paulownia are favourites) glassing with cloth is optional.



Turning a continuous round rail is the only shaping that is required.

There are possible variations on these construction layouts and the board dimensions can  be quite easily altered over a surprisingly wide range. The thickness of the board can be tuned for more buoyancy and less sensitivity.

The bottom curve can be increased by up to two inches for hollower waves and more manoeverability, or reduced by the same amount for maximum paddle speed, wave catching and glide.

By building the board as drawn, however, satisfaction is guaranteed.



To a builder with a boat or two to his credit, the board building procedure should be self explanatory. For first timers there are step by step instructions at this link.

Hollow wooden Nugget single with spitfire fin ready to go SOLD

Black graphite Power Surfboard spitfire fins have been called 'Patu' fins because they resemble the Maori war club of that name. This one is laminated paulownia glassed with thick blue Swanndri wool and epoxy resin. The Swanndri wool is equivalent in thickness to about 4 or 5 layers of 6 ounce fibreglass cloth.Here's the wee beastie all polished up with beeswax polish and ready to enter the water:The 4mm diameter fillet at the base of the fin can be seen here. The most hydrodynamically efficient fillet for a surfboard fin is between 2mm and 5mm in diameter, this can only be acheived if the fin is set into the board rather than glassed on.The small cutaway at the fin base improves the holding tenacity of the spitfire fin.Theplanform of the spitfire fins is the most efficient flat plane fin shape in existenceThe 'Spitfire' fin is based on the wing of the Spitfire WW2 fighter plane. We were the first to apply these fins to surfboards in 1995, and advertised them as Spitfire fins. Now there is another company ( Revolution surf) doing Spitfire fins, but we were the first by 11 years.The story with the Spitfire fin is that it has the lowest induced drag of any fin or wing planform, essentially this means that it has less tip vorteces and a better lift/drag ratio than other shapes. It is the fastest most efficient flat plane non twisting wing planform possible.It is interesting to note the turning characteristics of the spitfire compared with its rival the Messerschmitt 109. The ME109 with its narrower linearly tapered wing had a tighter turning radius than the spitfire, but the spitfire had a higher turn rate. In other words the spitfire could maintain such a high speed during the turn that it would complete a 360 degree turn before the ME 109 even though it travelled through a larger turning radius. The closest surfboard fin to the ME109 fin is probably the wavegrinder.Another characteristic of this fin other than low drag and its ability to maintain high speed through turns is its benign stall characteristics . When the Spitfire fin starts to stall it does so first near the base of the fin, this makes the onset of the stall predictable and the stall easier to avoid. In comparison the linearly tapering wing like the ME109 or the wavegrinder will give less warning of the impending stall and will basically spin out suddenly and without warning. The spitfire fin does have a higher stall speed though.The characteristics of elliptical planform fins were predicted by the classical lifting-line theory developedby Ludwig Prandtl and published in 1918."The first closed-form solution to be obtained from lifting-line theory showed that in-duced drag could be minimized by using anuntwisted wing of elliptic planform.The classical lifting-line theory developedby Ludwig Prandtl and published in 1918 wasthe first analytical method to satisfactorily pre-dict the performance of a lifting wing. Moreover,until the development of the digital computerin the early 1960s, it was the only analyticaltool available for wing design. Early compar-isons between results predicted from lifting-linetheory and experimental data showed remark-able agreement. Even with modern computa-tional fluid dynamics (CFD) , it is difficult to im-prove on the induced drag predictions derivedfrom lifting-line theory."http://209.85.173.104/search?q=cache:feNokN7nsukJ:www.aiaa.org/aerospace/images/articleimages/pdf/phillipsjanuary05.pdf+spitfire+wing+drag+theory&hl=en&ct=clnk&cd=1&gl=nzBottom line is that they are a very fast fin, with a high speed turning capability and a high turn rate.Goretex vent:

Rhino's 6'1" singlefin. . . free plans !

Update: The free plans were loaded up on Swaylocks surfboard design forum but since the forum upgrade they appear to have been lost along with a lot of archival material. The 6'1" Nugget singlefin plans are on DVD and are available from roy@olosurfer.comBack in 2005 a young Californian in his senior year at high school (who goes by the nickname of 'Rhino' ) built a 6'1" Power Surfboards parallel profile balsa board.Rhino asked us if he could post the plans and building process on Swaylock's surfboard design forum, and we agreed. The result was the 2006 Swaylocks thread'Free 6'1" Power surfboard plans'Rhino's 2006 ride report on his new board:" We finially had a decent swell here in San Diego! After riding about fifty waves in the last few days, I have a really good feel for my board. First off, it floats me just fine (I'm 6'2" 150lbs) and it duck dives like a champ! it rides super smooth and I can really feel the wave benith my feet. One of my best waves I cought the other day...It a was solid 5' wave, the drop was steep, but I made it in by stylishly droping into a very smooth bottom turn and following that with a nice little cutback. I was able to stay on the line for a few more seconds and hang a quick 5 before it closed out. I'll never surf a tri-fin again...unless I don't have a single handy : ) Cheers. "Well this thread popped up again today on swaylocks, 'Rese' who is also a senior high school student, asked how long the board took to make. Here's Rhino's reply: " I made this board my senior year of highschool as well. I worked on it for about 8hrs a week for a full semester then finished it up at home. I have maybe about 80 hrs total invested in to it & I've bee riding this board lots since I built it. It's surfed in waves from kee to 11+ feet and is pretty much a soul board. I mostly like doing big bottom turns on it, mild 'slow mo' cutbacks as i call them and likes getting bareled in fast clean waves.-Three years and counting without a single pressure ding!...a few fin chops though. Two other high school students in Japan and Canada have just built this board and are now in the process of glassing them! Go for it! & feel free to post questions. "