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.
