Olo of the Sun: deck planking

Deck planking continues:

 The deck will of course be concave or 'spooned' fore and aft, and nearly flat athwartships. This gives the best possible control for the rider.

 Heavily domed decks and tapered profiles ( especially when combined with extreme thin downrails which have the rail apex far below the rider's feet ) raise the centre of gravity and centre of effort causing instability and lack of control, they also reduce the leverage which the rider can apply via the feet, as well as  killing  beneficial flex. That's why we don't do them. I think of thick domed boards as Fat Guys in Tutus (FGT).

 Most people assume that a very long board will necessarily also be thick and extremely buoyant. My preference is however to use the minimum thickness which gives adequate buoyancy and strength. In this case the maximum thickness is 2.5 inches, and the volume is approximately 168 litres . . . a modest volume for a 19 foot 27 inch wide board.

 Thickness should be spread thinly and evenly, not lumped up in the middle of the board, at least in this bricklayer's opinion, which is in harmony with the laws of physics and his personal experience as much as possible.

A few questions:   Hi Roy, Awesome project. I was just thinking about all the glue and sawdust you'll be using. Huge effort. I have some questions on your method if you don't mind. How do you apply clamping pressure to the planks? It seems you have the bricks to keep them flat and even, but I can't see how you put pressure on them to keep them together. Doesn't the epoxy need the pressure to maintain strength as it sets? How do you get the rocker into the board? Again it seems from the photos the strips are being laid flat. If you bend them afterwards there is the inherent stress that will try to make it always flatten out. If they are laid bent that stress will be greatly reduced. (I think anyway). Thanks for sharing what you do (I wouldn't mind giving your method a go one day). A.....

Epoxy doesn't need pressure when it is setting, so very little clamping pressure is needed for the planking. Having said that I'm happy to let the glue lines be of varying widths, as I like the look it gives more than ultra tight invisible joints, it's also stronger that way. I'm able to edge set the planks sufficiently with just with a couple of dozen bricks, provided that the planks are reasonably straight. With problem planks I scribe and fit them.

As far as bending goes it's a breeze, a panel like the one I'm making is so flexible that it can just about be bent in a complete circle. The construction method is basically bulletproof and doesn't have the nose plank and spine cracking problems with the fishbone method sometimes has.

It's also possible to bend concave or roll into the board either by having lightweight battens on the rocker jig which bend under sufficient weight or by cutting the required curves into the jig battens. If the bottom is concave the deck will be sightly domed, but typically no more than a quarter inch.

There's no more built in stress in the planking if the planking is glued up prior to bending. For bending on to the rocker table I just use bricks and a couple of clamps in the nose area if the board has a tighter rocker curve there, which most of them do. It's good to have the deck and bottom in slight tension and compression in my opinion as it gives a better resonance, like a drum.

The parallel profile system is deceptively simple, I say deceptively because for the best results it requires careful balancing of the design parameters ( particularly of volume and thickness ) due to the fact that these are linked to each other in a way which doesn't happen with conventional boards. With conventional boards 'ad hoc' changes can be made, whereas with the parallel profile every change affects the entire board, which is why I feel that it's the haiku of surfboard design

Thanks for your questions

A question on nose diving

Q to Roy. do you think its a myth that a heavy nose will nose dive?

http://www.grainsurf.com/forum/viewtopic.php?f=29&t=3558&start=70
Well for a start that depends upon what one means by a heavy nose. It's obviously possible to make a nose which is so heavy via lead weights that it could never be lifted clear of the water by the rider in any situation, so  it's a matter of degree. When I'm talking about a heavy nose I don't mean one with a pile of lead added, but one with weight which is proportional to the volume of the board and with the same density as the board has overall.

In a sense the advantage of a heavier board which uses the weight of the nose to produce power and control can be described as the ability to make controlled nose dives. I imagine that what you mean by nose dives though  is when the board digs it's nose into the water or 'pearls'. That's what we don't want.

If the rider is to avoid nose diving or pearling ( in high risk pearling situations like steep drops for example ) due to the nose weight of a  heavy board then there are at least two methods he can use. 

The first is just to trim the board aft by moving to the back of the board thereby lifting the nose up. On long heavy boards in pearling situations this has limited effect. The problem is that as the rider moves aft the fulcrum between the nose of the board which is free of the water and the tail which is in contact with the water also moves aft, this has the effect of increasing the length of the nose and thus the leverage exerted by the nose. Thus the rider reaches a point where he can't lift the nose any higher, and also experiences control problems due to the leverage of the nose. Instead of using nose leverage to advantage to improve drive and control the nose leverage takes over and reduces control !

If that were the whole story it would be a disaster for long heavy boards, and would limit their ability to function. In many cases it does so. Standard longboard designs have this  nose leverage problem in typical wooden surfboard weights and in lengths over 11 or 12 feet ( nose length and weight both contribute to the leverage of the nose ).  An extreme example can be seen in videos of Tom Wegener's valiant but futile attempts to ride traditional Olo replicas using shortboard methods, where the rider's attempts to keep the nose out of the water from the back of the board fail due to the huge weight and length involved.

Fortunately such blunt methods are not the only ones available. The key is in the planshape curve through the tail of the board. If tail planshape convergence is increased and brought further forward than in the standard fairly parallel planshaped malibu longboards, then the rider is able to use nose weight to control the board, instead of fighting the weight he rides with it, directing its energy rather then opposing it. 

Here's a brief article on the subject called ' tail rail convergence and how it influences nose presentation angle':

http://olosurfer-woodensurfboardsatpipeline.blogspot.com/2009/03/surfboard-design-workshop-tail-rail.html

What it's all about is that the tail rail convergence allows the rider to roll onto a rail and lift the nose that way, without having to reduce the ength of rail line in the water, without having to make drastic aft trimming moves, and while simultaneously turning to get out of the dangerous  nose diving situation ( rather than bluntly opposing it) while maintaining speed and drive.

This method of control is the basis of all good longboard design, but it is very rarely used in mainstream longboard design, which is increasingly stuck in the parallel railed designs of the 1950's which are, and always have been, only suitable for short and mid length boards of relatively light weight.

A Roy Stewart surfboard design secret: Fore and aft mass distribution in longboard design.

 It's often assumed that if possible the mass of a surfboard should be placed as close to the middle of the board as possible. The reason for this is to reduce 'swing weight' by reducing the inertia required to swing the nose of the board through turns. It's also a concept taken from boat design where weight in the ends is avoided as much as possible in order to reduce pounding and pitching.

 Fore and aft weight distribution/concentration with surfboards  is however just another design element, and I don't agree that it is always better to have it concentrated in the middle of the board as much as possible.

Unlike the situation with boats ( unless they are surfing ) the majority of the force which moves the surfboard is not only proportional to mass it's also positioned and distributed as the mass is distributed. Because of this mass can be distributed towards the ends of the surfboard in order to achieve a desired result, as by moving mass we are moving the centre of effort and the distribution of effort.

So for example I use nose weight as a design element as it is used to provide motive power from the nose. This works as a means of assisting penetration and control on takeoff, and for control of glide path angle in general.  Thus for example in order to drop down the wave in a steep high line situation when trimming  one can use the motive power of the nose mass. If part of the inside rail is released the nose mass will exert greater leverage and will increase the glide path angle by lowering the  nose. This is very useful as it adds a whole new control method which surfboards  with lightweight noses are unable to use,  one which has great advantages over the usual methods of trimming forward or tail turning, as well as  adding to those control methods.

Turning and trim control using the method described is very organic and intuitive, it is also able to be used with great subtlety.

I've never seen this written about or spoken of before, nor have I seen it used in longboard design or properly in the water except with my own boards.

In order for the concept to be utilised effectively rather than incoherently in an ad hoc or accidental way, the board needs to have certain other design elements, fortunately these are also features which are required for other aspects of functional pure surfing boards, in a perfect example of the harmony which exists in design when one eliminates the spurious and unnecessary.

So this is an answer to those masses of uneducated people ( like Randy Rarick for example ) who say that if there's a lot of nose out of the water when one of my boards is at speed that it shows that the nose could be removed.   The answer is that the nose is doing vital work when out of the water ( provided that it has suitable mass )  I haven't mentioned the details  previously because although I like to share design knowledge  I also need to keep some to myself away from the prying eyes of the corporate vultures !