Malibu longboards and their inefficiency: four reasons why

Four  points  with regard to the inefficiency of the 'malibu' noseriding longboard type ( in its various forms) are as follows:



1) The separation of the turning and trimming areas. This is inefficient because it requires walking up and down the board in order to turn and trim. It also prevents carving turns at speed and forces the rider into an ungainly flapping surfing style which is detrimental to optimum positioning and to speed and conrol



2)Having the trimming position near the nose increases wetted surface area precisely when it should be reduced. Planing hulls do not work well that way.



3) The reverse rocker profile. efficient planing hulls should reduce rocker aft and increase it forward. Due to the artificial nose riding, tail rotation, and walking requirement the noseriding type usually has the opposite. . . more rocker aft than forward.



4) Balance. For good balance a surfboard should have a sweet spot in the middle of the board. This simultaneously reduces swing weight and nose leverage during turns, and allows finer control when trimming. Malibu longboards don't have this. . . the middle of the board is only used when passing through from one end to the other. It's like having a car with the accelerator on the bonnet and the steering wheel in the boot. 



For efficiency a rider should ideally be able to turn and trim simultaneously, this requires a sweet spot whereby both can be done from the same position.



Any board which has separate turning and trimming areas does not have a sweet spot as the rider is only able to do one thing from each position.

Efficient surfing requires the ability to turn for positioning while at maximum trim speed. . . rather than the jerky flapping stop/go approach dictated by the malibu surfboard



The Ten foot four surfboard below is able to turn and trim at speed from one position.

These two boards are able to turn and trim from one position, unlike the malibu board.



That feature gives them a huge advantage



The 70 pound 13'9" Dragonboard trimming from a central position, with turning available  via subtle  'fingertip' control or larger muscular exertion, as required.

The 12 foot Future Primitive, carving a turn while in trim. This board is almost never in static trim, it can snake through turns while trimming almost as soon as the rider thinks of turning, which as stated gives a huge advantage.

The reason why the vast majority of longboarders don't realise that they are riding inefficient, ungainly, ugly, ill conceived and badly designed boards is mainly because they never confront a well designed longboard in the water. They generally huddle together with those on similar boards, not doing well but secure in their poor performance because they are insulated from reality by scientific marketing and safety in numbers. When they confront a pure surfing  longboard like the ones above the difference in performance is often so vast that their happy deluded bubble is burst. . . with a variety of emotional reactions best left to the imagination !



A recently published description of malibu surfing as jerky flapping is a sober judgement of the type of actions required to ride the boards and it is coming from an intelligent adult. I stand by it.



  A reference to longboard riding 'style' made by a malibu apologist today in response to this article is a key to the discussion. Nearly half a century of marketing has dictated what looks 'cool' and what doesn't, but it has little to do with efficiency in spite of the entrenched attitudes it has created.



Furthermore if one ever builds and rides surfboards of over twelve feet in length one will discover that the supposed 'longboard' attributes of the noserider don't work in real longboard lengths . . . as they rely on light weight and shorter lengths to overcome their design deficiencies. They are not really classicly functional longboard shapes at all. That distinction goes to the curvaceous teardrop shapes of the pure surfing longboard



Eventually the truth will get through and longboard design will catch up with what we are doing, this will create a lot more joy in longboard surfing than the endless repetition of essentially awkward surfing and tired mantras which most people are forced to subscribe to at present.



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Roy Stewart's surfboard design innovations

We invented the parallel profile system of hollow wooden construction, and developed the tunnel fin independently, our many different tunnel fin setups are also unique.When the tunnel fin was first used it was not a success as it was not properly utilised or understood.The FP12 surfboard is also unlike any other longboard ever built.So here's a list of our innovations1) Invented the flexible parallel profile wooden construction system. ( 1994 )2) Pioneered the use of extremely wide longboards ( 26" to 27" plus ) long before the SUP craze ( 2002 )3) Pioneered the use of extremely thin flexible longboards ( Length to thickness ratios below 50/1 )4) Independently invented ( not the first to do so ) and developed th tunnel fin ( 1998 )5) Invented and used several multi finned systems based on the tunnel fin which had never been seen before6) Pioneered and developed the constant rail section7) Independently invented and devleoped the displacement tail ( some similarity to square railed sinker tails from the 1830's and 40's )8) Developed the spitfire elliptical planform fin ( surfboard application ) and the fisrt to use spitfire cutaway fins9) Developed the first ( and so far only ) modern olo surfboards, including much work on rockers for extremely long surfboards.10 ) Invented leading edge channels for tunnel fins. . . just for a start !:-) :-) :-) :-) :-) :-) :-) :-) :-) :-)

How decelerating surfboard rocker works

It's trendy these days to say that rocker 'pushes water'. . . but in reality rocker behaviour is a little more complex. More rocker curve in the nose provides more lift, this means that the board will lift up and plane at a lower speed, basically it has much better acceleration on takeoff than a board with a flatter nose rocker. As the board lifts onto the plane the nose is lifted out of the water, so that the lower lift lower drag tail can take over. Keep in mind that the amount of planing lift produced by a board increases as the board goes faster, so progressively less wetted surface is needed as the board accelerates.The idea that 'rocker pushes water' is based on the fact that more rocker equals more lift AND more drag. .. . but this just means that rocker should be used appropriately, knowing what it does. Keep in mind also that rocker is not an absolute it is always relative to the curvature in the wave . . . if the curve in the wave equals the rocker, then the board at that moment effectively has zero rocker. By having a huge amount of nose area with a lot of rocker, what I'm doing is making a board which has a lot of acceleration on takeoff, due to the huge amount of lift produced. Of course such a board has to be actively driven down the face on takeoff in order to utilise the nose area.If one looks carefully at the following video it can be seen that the board has tremendous acceleration on takeoff. .. .. . in fact none of the flatter nosed malibus out in the water that day could accelerate fast enough on takeoff to make the first section. Once the board accelerates to a higher speed the nose visibly lifts out of the water:This knowledge has been used for shortboards and 'gun' boards since the 1960's, and in boat design:

Surfboard design workshop: The displacement tail

Here's a quick introduction to the displacement tail design, in the 1940's they were know as 'sinker tails' but had not been fully developed as they still had square rails with hard edges and not much fin area.The displacement tail has to have ultra soft rails with no edges and should be really narrow. . . and thick. . . so that it can sink in and out of the water without catching or stalling. Actually in the video of Randy at Sunset point he was trying to stall right off the tail and the board didn't stall as dramatically as a wider tailed hard railed board does, it is too smooth for that so it just keeps on rolling. Also the displacement tail relies a lot on the fin for lift ( with soft rails and not much area in the tail it doesn't produce a lot of planing lift ) so needs to have a big fin as well as a lot of useable rail convergence in order to set the fin at the angles it needs to lift properly.. . . this again equals a narrow tail..

Power surfboard design goals and the make it easy school of pure surfing function

My design goals are to make the waveriding experience as easy as possible and as successful as possible in terms of wavemaking ability.In order to achieve a better result in that respect than the typical malibu noserider does isn't all that difficult, and in some ways is just an extension of the same principles used in shortboards.Basically if a designer makes a longboard without reference to noseriding needs then a few things will naturally happen. . . the planshape will become more curvaceous, the rocker will no longer be reversed ( it will be even or will gradually flatten towards the tail rather than being flat in the nose and flipped in the tail ) and the rocker apex and widest point in planshape will come closer together.The net result of these very simple changes is a board which has a sweet spot from which it can be turned and trimmed. . . . a major advance in efficiency which makes life much easier for the rider. The board will also become faster, will handle late drops better, and will rail turn better ( rail turning is more efficient )When life gets easier for the rider then the surfboard becomes less obtrusive ( yes even if it is very large) and the rider is able to make waves which he wouldn't otherwise make, as well as being free to use his powers of concentration to improve his wavemaking ability rather than having them occupied just trying to achieve the basics, or even worse doing unecessary tricks.Rather like the guy on the well designed bike compared with the guy on the chopper.I'm not saying that anyone has to see it the way I do. Plenty of people out there at present are promoting the idea that the holy grail of surfing is to make it as difficult as possible, that's not the way we do it around here, and it's not the way Bentley, Rolls Royce or Ferrari design their cars either. . . make it work as smoothly and efficiently as possible so that it all happens at the touch of a finger or toe.Roy StewartPower Surfboards

FAQ What does your ideal surfboard rocker look like ?

The actual amount of rocker in inches depends upon length, the planshape and other factors, but the basic rule I follow is that the rocker should not increase towards the tail.There is a very good hydrodynamic reason for this, namely that a flat rocker has less drag and makes less lift, whereas a more curved rocker produces more lift and more drag. So, just like a powerboat the board should have a lot of rocker in the nose to provide lots of lift when moving slowly, as it accelerates it should lift this high lift high drag section up out of the water and use the flatter low lift low drag areas toward the tail. This happens progressively as the board accelerates, and it also allows the board to reduce overall wetted surface area as it accelerates ( less area is needed as the board accelerates as it produces more lift per square inch of wetted surface area. This kind of board naturally trims aft with a nose up attitude as it accelerates.As far as the actual shape of the rocker goes, the very simplest shape which is a decelerating rocker ( i.e doesn't increase towards the tail) is a circular arc rocker. I use these sometimes, they have an even curve from nose to tail. An increase in efficiency can be had by progressively decreasing the rocker via elliptical nose rocker and circular arc tails, or an elliptical or parabolic rocker section throughout the board. . . they all do a similar jobOne of the first flashes of inspiration I had regarding rocker was that it is in many respects like an underwater foil section . .. .. . one can't go wrong using a foil section for a rocker.So if we take any good foil section it will make a good rocker. . .. and not only that it will make a good planshape.Foil cross sections can be used to design the entire board. Look at the cross section, there's your fin cross section. Look again, there's a planshape curve , look again and there's a rocker curve. Of course the rocker will have to be proportionally flatter than the planshape, but the same shape will do beautifully for both.Foil sections have a widest point, this is usually between 20% back from the leading edge and 50% back from the leading edge. Since it is best to match the position of the wide point and the rocker apex ( we call this 'matched foils' ) it is convenient to use the same foil curve for the same board. Of course with the rocker it isn't necessary to use the entire nose section as the board isn't operating underwater, basically a bit can be lopped off so that the tip of the nose doesn't wind up pointing vertically up. . . . . no harm if it does thoughDoing it that way is just about foolproof, it's a virtual design kitHere are some NACA foil possibilities, all of which would make a good rocker. There are lots of other foil sections.

Six foot 'Nugget' with spitfire fin

The board and fin are not polished yet, but here's the setup:

The truth about rocker: Measuring the stuff !

The usual methods used by boardbuilders to measure rocker are almost meaningless, as the 'baseline' is placed arbitrarily.

To make matters worse, no one ( apart from myself) ever bothers to measure rates of curvature. Without knowing the rate of curvature it is almost impossible to compare rocker on boards of different length.

As an example of this, one would probably expect that an 8 foot tail section with 6 inches of rocker has 'more' rocker than a four foot tail with 1.5 inches of rocker, when in fact both these tails have an identical rate of curvature. The usual way of measuring rocker is completely unable to show this, and in my opinion this has led to anomalies in board design particularly in very long boards.

In fact we have found that any functional rate of tail curvature can remain constant over a huge range of board lengths, we have used the same rate of tail ( and nose curve) and in fact the same rocker table for boards of similar planshape proportion ranging from 6 feet to 17 feet with excellent results. This is not to say that we always use the same rocker curve, we don't, the point is that it is important to get a handle on what rates of curvature are used.

The typical assumption and tendency has been to reduce the rate of curvature as a board gets bigger, this is in my opinion quite clearly an unintended side effect of the standard rule of thumb rocker measuring method. As shown above, a board with the same rocker curve gets a much larger overall rocker measurement as the board gets longer and the curve is extrapolated, this tends to make people believe that the longer board has too much rocker, they then reduce the rocker so that the number sounds more reasonable. . . . . and so that the board looks proportionally like a shorter board. When they do this they still think that the longer board has 'more' rocker even though it now has a flatter and lower rate of curve. This has lead to a woeful anorexia of board rocker in longer boards, and generations of blissfully ignorant boardshapers, who unsurprisingly find that the very long boards they attempt don't work very well.

In fact, waves respond to the actual bottom curve not the 'look' of the rocker, so to the wave it doesn't matter that a very long board viewed from the nose looks excessively rockered due to the foreshortening effect of the viewpoint. . the wave reacts to the actual rate of curve, the same rate that looks very flat on a shortboard!

I often get asked why my longer boards have so much rocker. . . . .unfortunately the questioners usually have neither the inclination nor the power of concentration to listen to and understand the explanation given above. What I usually say to them is that the rate of curvature is probably less than what they have on a shortboard. . . they don't believe or understand this either, but at least it's short and sweet and saves me from wasting my breath


Let's look at a few boards to see how this looks in parctice.

Below we have a 6 foot Power Fish, now I probably shouldn't tell you this as it has been a secret for many years, but this board has the same rates of curve and comes from the same rocker table as the apparently ultra rockered longboards further down the page ( The X-15 and the D11-9 )





Here's the mighty X-15 showing a full 9 inches of rocker ( and only an inch and a half of thickness !)


And the D 11-9 with 6 inches of rocker:



FAQ: Why only one rocker measurement rather than two ? The answer to that one tomorrow.