Concaves, Chines, and Bevels

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.

2 (282)

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. 


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.



17 thoughts on “Concaves, Chines, and Bevels

  1. Hello


    – 100% safe for your site
    – real visitors with unique IPs. No bots, proxies, or datacenters
    – visitors from Search Engine (by keyword)
    – visitors from Social Media Sites (referrals)
    – visitors from any country you want (USA/UK/CA/EU…)
    – very low bounce rate
    – very long visit duration
    – multiple pages visited
    – tractable in google analytics
    – custom URL tracking provided
    – boost ranking in SERP, SEO, profit from CPM

    CLAIM YOUR 24 HOURS FREE TEST HERE=> [email protected]

    Thanks, Elana Withrow

  2. Neil, what’s the relationship between concave and rocker?

    Do you make a board with a certain rocker and keep the concave uniform so it’s the same curve relative to the rocker or is the deepest part of the concave(s) the “new”rocker once they’ve been shaped and blended together?

    1. Hi Dave i have a uniform rocker and i blend the concave through the bottom of the board blending a single into double concave and depth depends on surfer’s weight and wave requirements.

      1. Thanks Neil, I always wondered how concave affected the inherent characteristics that rocker gives.

        I guess it makes sense that where the concave runs parallel to the rocker at least through the business end of the board then it shouldn’t affect it?

        On the other hand if that dynamic changes then there is an effective change to the rocker?

        Ever curious about my equipment as my surfing progresses.

        Thanks again

        1. Thats good I can elaborate more about rocker as the one I use was a long drawn out process it didn’t just happen… Trial and error a lot of injuries a lot of different shapes. Concave is the great feeder of flow it also holds in critical sections of the wave.
          Regards, Neil

  3. Is the chine bevel more suited to three fin or four fin setups?
    And can you explain the pros and cons of the two please

    1. Mitch- it’s suited to both, I have 5’10” Fresh Fish 4 fin it’s the full nose no wings fish-tail with chine bevel concaves. And I have 6’2″ 5 fin double flyer swallow-tail Freak which I ride a-lot as a tri-fin and it has the chine bevel concaves as well, it’s brilliant! So they are suited to both models tri or 4 finners. On the Fresh Fish which is a classic hot-dogger the chine bevel combo gives you a big reward for your effort, you push into a turn and it will come off the bevel into the chine rolling right over onto your rail, lifting you with drive through the flats and weak spots, when it is sucky they slot nicely into the pocket and follow your head wherever you look and lean it will go. 6’2″ as a tri again driving through turns if you want to go long out of your turn or change your mind and go straight up into the pocket for a snap, it will comply. The chine bevel has a holding effect is stable and will sit and slot in the tube like you are on railway tracks, suits both 4 and tri NO problem!
      No easy explanations Mitch you should try one. I lent mine to a mate once after talking for hours about its capabilities he came back after one surf and ordered two of them!

    1. Mitch- concave closed, not open? Was a question asked by an interested person. So I explain it this way, 6 inches down from the tip of the nose on the bottom I start the single concave entry point, it’s shallow at the start and then grows in depth till it hits the start of your kneeling area and turns into a double concave deeply. So it’s not really closed, just shallow at the start. And of course you have the rocker/ nose lift too in that area, that is the start of the feeder to the rest of the bottom of the KB. And it’s bevel chine right through there, so the slight concave starts and then deepens as she goes toward the centre and then fans out into a double concave between the fins.

  4. From 2nds to channel to a big bombora wave I’ve ridden most of your shapes I still think the freak shape is the best all rounder you’ve ever produced Neil, it gets my adrenalin to peak very easily never a dull ride.

  5. Excellent info. It seems double concave is beneath the weight/knees. Any thoughts on channels (even just 2 big chanels) under the knees?

    1. Denis- channels under knees? Had many from 6 starting forward of widest point and straight out through tail. The half moon and clinker channels that ran about the length of your shin there were 4 of them, 2 either side of stringer. Straight under where you kneel some kneel in centre, others slightly forward of centre and others back behind widest point and still others right on the tail, so you have to adjust channels accordingly.
      2 channels under the knees big ones?
      I have found that they can track or skip so after many goes at different types I think a double concave right under where you kneel, one for each knee and faded out through fins, achieved what I was looking for. But look give it a go then you will experience the feel, it might be great for you, sometimes as you know what works for one doesn’t for another and vice a versa.

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.