I just woke up to find Surfding shot this over to me…without pulling up Bill’s comment on Surfline, I will say this…then come back. KCasey has got a pretty good grip on it.
Demarcation of rail
Heady thoughts indeed but to paraphrase some of these comments, let’s put it into practical application. Even if we retain the same design elements at one foot up from the tail, rocker, thickness flow and ‘end the tail’ at the same place, you still have differentiation that exists by the choice of tail design. Surfding’s diagrams displaying a roundtail with a small butt crack is probably the closest to the board **appearing **to be virtually unchanged- at least noticeably by the vast majority of surfers.
That doesn’t mean that sensitive instruments couldn’t measure and record subtle differences in dynamic flow characteristics between the two configurations. The “practical applications” that I personally experienced can be demonstrated by hopping on your choice of tail designs and getting towed behind a boat. On numerous flat days I would go ‘free boarding’, and one day I started to notice the difference in release from tail to tail. You can experience this yourself. Just take out a rounded pin and watch the line that is apparent off the tail opposed to two lines releasing off a dove or swallowtail. To extend that further, watch the FOUR disstinct lines releasing off a swallow winger.
If you wish to extend this observation further, try a diamond tail, a double winger and even the differences on a bump versus a definitive wing. Take a square tail out and see if you notice any significant difference between the two release lines of a 5" wide square tail and a 5" wide swallow tail. Is there a void in the wake of the square tails width?
Long time friend and co-shaper for my 80’s company, Bob Krause, once quipped to me “wanna cruise? Make a canoe. Wanna go fast? Chop it in half.” True to that thinking, when we designed race boards for the “California Speedcheck” held in the 80’s at the San Luis Reservior, our design, a square tail, achieved the 2nd fastest peak speed as recorded by radar. The winning board was ridden by speed czar Fred Haywood, on a Jimmy Lewis design. Both Lewis, and our design then achieved the fastest times in the world for a wind driven hull…
Since I haven’t read Stretch’s comments yet, I don’t mean to take anything out of context. However, I will state that if there are only two tails with all things remaining equal…and IF Swaylockians are ready to take this as truth, then I suggest you delve further into the subject.
Bat Tail = three distinct (fine) lines from tail
Diamond Tail = three distinct lines from tail…different ‘void’ from bat tail (significant shortening of rail length)
Round Pin = One line from tail slight rooster tail
Sharp Pintail = One line less rooster tail (specific singular pivot point esp. off top of wave)
Round Tail = One line from tail - non distinct rooster tail due to increased outline curve/allows subtle direction changes
Square Tail = Two distinct lines from hard corners
One set (pair) wings = add two distinct lines to appropriate tail design
Double set wings = add four distinct lines to appropriate tail design
Triple and multiples = just times by two…you get the picture…
Conclusion: ANYONE supporting the supposition that there are only two tails (whoever that person might be) is subscribing to a design reality that I do not adhere to.