I think there's a lot more in a SUB than just the rails and fins.
AT LAST.....Well Said Bnaccas.......... its the god dam width of a SUB that we need to keep us comfortable while hunting waves with our high C oF G.
People keep making comparisons with other craft, we cant do that so much with SUB's
The C of G dictates the width.
And the width dictates where we have to stand to hold an edge, certainly a fine low rail will provide more bite into steep wave face, but when boards get short we need all the roll stability we can get by adding width & rail buoyancy.
Have a look at the shots of Tahiti & Indo in the Starboard catalogue, some great shots of how to make a SUB rail hang in......STAND ON IT.
Next time your on a vertical wave face, have quick look at where your feet are in relation to the centre line.....particularly the back one! Your standin on that fat sucker of a rail to make it bite. (thats normaly not done with a goat boat or 6' short board is it! being comparativley narrow)
This is where it gets a more complex, to be able to stand on a rail at high speed, the fins have to be working well.
Its a bit like nose riding a board, if you have too little a fin area you side slip easyer/sooner. Drive is needed to keep the rail imbeded in the wave.
The shorter SUB has much less rail length to have to manage, so we get away with it for longer.
A very good reason why not to use low rails on a short SUB is the greatly increased tendancy for catching rail.
And of course there is the rider skill level......some people can ride piece of drift wood & make look good.
On this small wave below, its interesting to study how the far the rail is imbedded at a relativley low speed by the drive from the fin & also the very round board outline lets the wide point into the wave, far more than a long board with its greater area/buoyancy.
But as speed increases, the water pressure under the board will lift it further out to a point relative to the riders weight.
I have a 10mm concave under the front third of the board providing much lift & also tends to turn the the rail down into the wave giving grip/stability while on the nose.
.. Honestly.. No.
