Best Tail Width for Your Weight for Everyday Waves

Best Tail Width for Your Weight for Everyday Waves

I’m 175 and can’t get over one of my surfboard, I’m trying to figure out
why.  Currently I think it has to do with my weight and how this
interacts with volume and surface area… specifically, as of this week,
I feel it relates to the surface area in the back third of the board (or more specifically the “wetted” area of the board).

I was once told by respectable/older/experienced fin shaper that the back third of your surfboard catches a wave… this rung true to me. Thus, In my mind and experience the back third of your board determines your ability to grovel “everyday” waves. Which brings me to my current questions (somewhat retorical/ somewhat not):


  1. Was it an arbitrary choice to pick measureing the tail width 12" up from
    the tail?  Or was this optimized to the general fin placement or
    centroid of control or something?

I imagine it was arbitrary given the industry standard… but I’ve found many of the standards have been optimized for the typial intermediate surfer (who weighs around 155 lbs)

  1. I want to know if anyone has scaled tail width ( or surface area at the “key” part of the board) to weight for everyday waves?

I imagine that your weight affects plaining as a squared function of speed in the ‘wetted’ part of the board… or the back third to simplify.  The could probably link to current standards by directly related this to board width by tail type. (Ben don’t answer this one)

Tom G

“Imagination is more important than knowledge” an Einstein quote

“knowledge is no longer power when you can just google it” a quote by me

You’re right in your approach, but weight isn’t the only parameter in relation to surface area. i’m thinking of back foot strength, as I know guys who are fairly light but who can easily sink even a rather wide tail, whereas some guys (me, for instance, about 180) have a “weak” back foot and will be more at ease with a narrow tail.

foot size also.

Im 80kg ( ok maybe a bit more! ) and 5'9'', and i like my 5'8'' egg with a 17 1/8 wide tail. My other fave board ( all time fave ) was a 16'' wide tailed twin keel. But i like foam!. None of the boards i have have less than a 15'' tail. Fat arse's rock!!

I’ve never scaled tail width to weight because, as it’s been said already, there’s too many other factors. I have, however, come up with a little formula involving tail area on boards with really wide fish tails… those retro fish. I pay a little more attention to swallow depth and shape than most, who’ve said it doesn’t matter much. But I disagree. And it’s partly for the reason you hinted at… surface area… and partly for how water flows through the swallow area and releases out the back.

I believe tail volume (and tail rocker) has a lot to do with wave catching, while area (and rail/bottom shape) has a lot to do with planing. So both volume and area have to be “correct” for the rider and wave.


I’d love to know your little formula for fish butt crack depths.  I usually make them one half the distance between the tips.  Sometimes I make them a bit deeper. Care to divulge?  Mike

Thanks NJ and all.  Keep em’ coming. I’m going to try to make a simple survery to get to my point.

For me it has to do with planing surface.  15 1/2" wide if I need help keeping up speed on mushy waves.  13 1/2" for my step-ups.  I’m 210 pounds.  But you can’t look at tail width only.  It works closely with rocker, fins and concave/ Vee.

A wide tail/ Vee/ small  3 fin set up could ride similar to a narrower, single concave, quad.  What I’m trying to say is that different features could have counteracting effects that would cancel each other out.  Vee tends to stabalize, so do fins.  Deep Vee and Small fins rides similar to single concave big fins.  Not exactly the same, but similar.  Look at everything and how they play off each other.

need to know too many things to be a basic guideline for tail area , consider the variables such as surfers technique, waves ridden, different board design, fins, the number, the size and the placement all effect how a board will perform and how much tail area is required, then personal preference to work with one surfer and get what works best for him over a few boards, but then again I have never been one to follow standard guidelines, rather see what works for the individual......


No one on Swaylock's is a Typical Intermediate Surfer and very few of us weigh less than 155.

I like wider tails. Rarely do I have boards hold up on a critical lip. I agree with a lot said here regarding vee, tail rocker, fin spread and depth, foot size, style, etc.  

I would only add that the 12'' up measuring can be misleading. I've surfed boards that were 16'' @ 12 but which then pulled dramatically in to rounded pin. (This, as opposed to a classic fish or Simmons, which are more parallel in plan shape.) The tail as I described enjoys many of the positives of a wider tail but the wide point serves as a pivot point that works in conjunction with tail rocker. On a tail like this, I like the side fins farther up and the center fin farther back (to pivot off of). But that's just me. Good luck, C  

I’ve found that removing 14% of the surface area of the last foot of board, combined with a certain tip shape, is ideal for retro, twin keeled fish… although I’ve never tried it with a quad setup, to be honest. Everybody seems to be happy with the results, and I use it with a pretty specific bottom config as well.

Here’s what I used to do to get tip-to-tip distance and depth of crack… now I have templates. It might look complicated, but it’s really not. Start with your tail width number… this example uses 16.5 tail width a foot up:

1) Multiply your tail width by 3.23, then add 2.82 to that number.

            ex. 16.5 x 3.23 = 53.295 + 2.82 = 56.115 ****


2) Take the square root of that number, then add 1.68.

            ex. The square root of 56.115 = 7.49 + 1.68 = 9.171


3) Divide that number by .749, and that is your tip-to-tip distance.

            ex. 9.171 divided by .749 is 12.24. Or, **12 ¼ inches is your tip-to-tip distance.**


To get your depth of crack, just multiply the tip-to-tip distance by .49.

ex. 12.25 x .47 = 5.75. Or, **your crack should be 5 3/4 inches deep.**


I have a similarly cumbersom system for getting the right shape tip, if you haven’t had enough yet…ha!

Thanks a bunch for all the info. I’m learning a ton.

I love equations, but I prefer them to be non-dimensional… otherwise I feel they’re only valid for a small range… but if that small range is 175-180 lbs then I’m stoked!

My thing is I’m a speed addict.  I find wider tails help me drive faster in smaller and bigger waves… it’s the potato chip short board that is perfect in hollow chest high waves. I think due to the steep curvature for gunning down the line and keeping your rail in the water (again, thank Ben for insight into curvature matching of board to wave).

Do any of you 180lb guys land airs?  That’s who I really want to hear from… I’m sure there aren’t many… but that’s my point.  Damn gravity… the heavier you are the better waves you need to air.  Watch Groms air feet over the lip on waist high waves and big dudes like Jordy wait for shoulder high bowls to get inches over the lip (an exaggeration of course to make a point).  I think the heavier you are, the harder it is to find the right board. Damn physics… why can’t there be surf in the salton sea.

The limiting factor with this formula is wide point. On a board like this, I’d rather work from the tail up to lay out the planshape. I know… sounds wrong. But this goes back to the original post - what’s the right tail width for the rider and wave? I find, on fish, if I get the tail width right, set the tip-to-tip distance, and let my wide point flow from that, I get a good result fairly consistently in terms of a nice, flowing, fair curve… keeping my nose and tail widths the same. There is some room for adjustment, but my theory is that the bottom of the board, and the last foot of tail, on a short board like a fish… that’s where the rubber meets the road. Get that right, and your half way home.

wide as you can and still be able to turn it like you want