New board I got from Parkes a few months ago. Been meaning to make a post about it, because it's the best board I've ever had ............ And that’s saying something.
Firstly its another big concave board- this one is 15 mill at its max depth. The concave is nose to tail.
A little history: I've been riding boards with large concaves for quite a few years, first with fishes and now (for the last two boards at least) with rounded pins. Half the boards have been tris, the rest quads. And going farther back than that, my first large concave board was made by Steve Artis in circa 1975 from HB.
With the concaves I'm riding now they go extremely fast, but they are edgy, which means you need to pay attention when you are riding them. But the rewards, for me at least, have been well worthwhile.
The boards are edgy because 1: the rider has to be in tune with the board more so than normal. 2) the shape has to be perfect to keep the rail line out of the water.
There's no forgiveness if the board is too wide near the nose or the rocker rail line/ rail profile is a bit out. To illustrate: Consider the exact opposite is a complete veed bottom design which lifts the rail line higher to make sure it's far out of the water. But you lose speed, apparent planing area and the ability to ride as high in the wave (the vee bleeds water off the edge of the rail). But a vee'd board gives you an easy ride and allows the shaper more leeway if his rocker, rails etc are a little bit out.
Why are concaves good?
Easy….
Educated guess (via Dunc originally I think) they go fast, courtesy of less push from the rocker. Especially the reduced rocker on the stringer line. In low power situations the boards have a tendency to keep 'running' longer than you expect them too. It's an odd feeling because just when you expect the board to die cause the wave is gutless and you're stuck behind the lip, the board will keep cruising - thanks I imagine to the reduced friction.
Concaves want to plane between turns, it's their natural state. And the more they plane, the faster you go. This planing also helps you project out of a turn .
But what's so good about a big concave as compared to a ‘normal‘ concave?
Well traditionally concaves have always had the reputation of sucking onto the face, of wanting to track etc. I've heard mention once that some that bog down. I imagine part of this reputation comes from two places 1) standup boards 2) and from the most common concaves that people use - 4mm? Single to double etc.
The thing about kneeboards is that they are so wide - relative to a standup board. I think that makes a huge difference in the way you can plan a kneeboards bottom contours.
Because of the width of a kneeboard given the correct depth of concave you'll find that the board will be operating much like a catarmaran in some parts of the wave. At this point there isn't any meniscus joining the two panels and consequently a lot of the "sucking" onto the face that people attribute to concaves isn't so apparent with these boards..
The interstitial spaces (some of the time) are being filled with air. In my old fishes, when you flicked off and let the board run slowly over the back of the wave, you could hear the trapped air gurgling out. Same when you came up after a duck dive - the air would be trapped under the board and come out in huge bubbles.
Apart from the concave, what's special about this board?
Well, we've taken as much of the main rocker out as possible and instead moved the curves over to the planshape.
If you look carefully at the rocker you'll see that it's playing with the concept of a 'board within a board' - meaning there are two boards here. The board that sits in the water and the part of the board that is just there for emergencies - which is the nose lift. For those who lived in Sydney in the seventies you might remember the nose lift on summer cloud boards? Rumour had it that the shaper used to pile bricks on the blank to get more nose lift.
So this new board of mine is a bit of a nod to those days - without the bricks. The extra nose lift comes in handy for late takoffs - but stays out of contact with the water the rest of the time. So though the board is really five eight, in some ways you could be riding a five five.
In most ways it's an extrapolation from the last board david made me - which was for small waves and had double flyers/wings and quite square floaty rails in the tail. That board was excellent upto six foot oddly - yet the tail rails and flyers made the rails pop on big cutties. (remember it was a board made for two foot and under.
So with the new board we've taken out the flyers and given it easier to bury rails, but kept the concept of very flat rocker and lots of planshape curve.
One other thing which has made a big difference is keeping as much foam in the blank as possible. Having that 15 mill concave on the bottom takes a lot of foam out of the blank and you lose a corresponding amount of flotation (my first fishes with large concaves were about 2 and a bit inches thick under the chest - which was great for duckdiving, but lousy for paddling.
So this board with its flat rocker and very flat stringer line (courtesy of the concave) plus a small amount of extra foam has given me aboard that paddles super early into a wave - and it's only 5 foot 8!
Random observations:
Interestingly if you stick your head under the water and push the board round you'll find packets of bubbles about eight inches wide travelling from nose to tail and off the end. Of course this doesn't prove that happens when you are riding it ...
If you are going to make one for yourself watch the rail fifteen inches from the nose. This will be the unsweet spot if your rail line is out.
Tris and Quads: When I changed my first quad to a tri for a while I noticed there was a definite feeling of running on the inside panel when you were doing bottom turns - it was a good feeling but weird. Exactly like skiing on one ski.
My style? Its probably relevant: I ride from the tail kneeling very high and leaning forward to bury the rail on my quads. I also ride forehand/backhand (my backhand is crap) With the latest board I have discovered the advantages of leaning out as well- leaning out helps keep the rail out of the water and build up more body torque..
Riding them? It doesn't hurt to drive them hard, so if you were bought up in the single fine era it's something you'll appreciate. That said they are as loose as a normal board - if they are too tight, then it's probably your fin position or fin rake, rather than the concave.
Downsides? Ribbed waves, waves with steps etc are a pain in the backside. Lucky I don’t get to ride them much :0
Thanks for reading...
Last random observation: These ramblings are my observations after 35 years of kneeboarding - but they aren't necessarily right
Cheers headwax
(I had some spare time this afternoon - can't you tell?)
edited 27th november: took out a line
