I got some great questions from my last blog so I’m going to answer them. You could write ‘War and Peace’ about concaves, chines and bevels but I’m going to try and condense it here as best I can…
A single concave into a vee in tail, I have done many and I have found that they work best on tri-fin rounded pins. In actual fact, you can vary the depth of the concave from shallow to really deep, whatever you require. Ending up in a vee in tail, a concave vee in tail, or a concave running out through tail. I have ridden a heavily rockered bottom with a deep concave from nose to tail and from rail to rail – board was like a banana – it was a rounded pin tri-fin. Went fantastic in hollow waves, for vertical surfing and deep tubes, but didn’t like slow, gutless, flat waves – would not run. Was not a good all-rounder, if you were only able to have one board. Great fun in your quiver for special occasions.
A single concave, 6¨either side of the stringer, continual nose to tail is a goer in a medium-rockered KB. You can have it as a tri-fin or a 4-fin and releases water through fin area excellently. With a tweak of extra tail lift. Concave will always rise to the steep part of the wave. That’s why they are great for speed and momentum. You have to find your comfort zone of what suits your style and helps you progress. You can have concave vee or just flow it into a raised vee to release water quickly. And flow is the go.
Why is the concave in the nose closed and not open? I do it like this to feed the deep part of the concave and where most of a surfer’s weight is is where it deepens. Pressure means power into your turns.
BEVEL / CHINE COMBO
I know you can’t have one and not the other. For me, combo is a bonus. You roll off the bottom bevel as you are driven out of your turn from the concaves onto your chine rails. It all works well together, particularly gathering speed through your turns and holding you in steep, hollow waves. The bevel chines through the nose allow you to turn quickly either way you require to go and to take off quickly and get going. It is like an ‘arrow head’ if you look at the profile. Either with full or pulled-in nose they are great on late pull-into-the-tube takeoffs. They are user-friendly, average-punter has no problem and they will improve your surfing. I, without hesitation, put a single to double concave that continues onto a concave vee on all boards with these bottom and rails.
This all needs to be together for all aspects to complement one another and really, I have found it a very versatile bottom and rail combo. I have surfed this combo on a huge variety of waves: junk, perfect, small, large, flat, hollow… and I cannot fault it. I personally recommend it.