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  1. #1
    Join Date
    Jan 2009
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    milton delaware
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    What is the purpose of this tail?

    A couple of sessions groveling in knee thigh high waves this week has motivated me to shape a "grovel" board for REALLY small weak conditions. Lined up clean 1-2 foot waves with slopey faces....Long slow waves that would make the average grovelor bog out. something that will get up and plane on mush.

    I know i want something around 5'10" x 22" with flat rocker. SO many people are making boards around that size with this kind of tail (below). Ive never been able to get my brain around the functional purpose of this kind of wide, cut-off tail. Any ideas...will it work in small weak surf? What is the idea behind that kind of tail to begin with?

    Last edited by mitchell; Jun 10, 2011 at 11:32 PM.

  2. #2
    Join Date
    Nov 2008
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    bethany & wrightsville
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    it may be the extra volume and width that helps harness more of the power from such a small wave, that is, more board touching the water will lead to more thrust it can take from the wave....but Im not sure either, good question/thread

  3. #3
    if you don't know, you can't ride it

  4. #4
    Join Date
    Sep 2009
    Location
    Norfolk, VA
    Posts
    396
    There's more to it than just the tail width. It's the zero tail rocker & "S" decked rails, as well. Essentially, the entire design is based on getting on plane fast & maintaining that speed with control. While the purest version of Bob Simmons' designs work better in lined up waves, I wouldn't say that they are good for slow waves....especially weak ones .

    I have 2 different versions of this board. Both boards start at the nose with upturned rails and evenly transition to the hard, downturned rail a few inches before the fins. They are also both 3-tab FCS keels, with twinzer boxes (which I use now in both).

    The first one has about an inch of tail rocker and 4.5 inches of nose flip. The bottom has pronounced belly for the first 2/3s of the board that rapidly transitions into a giant concave out the back. Planshape is an extremely mild curve, thoughout (like the one in your pic). This board is incredible in thigh to slightly overhead waves. Even in the larger waves, it holds incredibly well (and I was using FK-1 fins without twinzers). Very loose and a respectable amount of drive. It's not cutting through a turn like a thin-tailed thruster, but you don't miss it. Surprisingly, it can go vertical. "Fast" does not begin to describe the acceleration. I haven't found the wave size limit on this board, yet.

    The other has zero tail rocker and about 2.75" of nose flip (yeah...it's an ironing board). The bottom starts with a very mild belly for the first third and completely flat bottom for the rear 2/3s. Planshape has parallel rails & an even fuller tail. Really, really thick and barely has any taper at the tail. Basically, a rocket sled. Still working the fin setup. The straight rails & minimal belly make it catch ripples,but don't let it turn as easily, so I replaced the FK-1s with MRs to experiment. Everthing about this board is for the typical small (knee to thigh) & windless (fast breaking) surf VB gets. The same attributes that make it a good VB groveller, restrict the wave size it can operate in, though. After thigh-high, it starts to pearl. I'm interested in finding out if that lasts throught the wave size scale or if the straightness loses it's pearling affect after a certain size (like above to shoulder ).

    Hope that helps.
    Last edited by Ray F.; Jun 11, 2011 at 03:42 AM.

  5. #5
    Join Date
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    Ray,

    What length are your two boards....with the 4.5" and 2.75" NR? I shaped a 5'5" a couple years ago that only had about 2.5 - 3" nose rocker, and had the same experience...in small mush it worked well, once the waves had any kind of pocket, the board didnt really fit, plus it was a retro fish with deep swallows/keels so that tail didnt make much sense as a grovelor anyway.
    Last edited by mitchell; Jun 11, 2011 at 10:34 PM.

  6. #6
    Join Date
    Aug 2009
    Location
    Monmouth Beach, NJ
    Posts
    2,308
    This is a VERY complicated topic. RayF gets it... The Mini Sim is a board designed with a number of complementary features. Change one, and you change the entire ride. Not to say that it won't work... it will. Just differently. But if you're talking about a wide, square, flat tail, there are some generalizations...

    Wide square tails are notorious for not not working well on a rail. But there are things you can do to compensate...

    Soft edges. They minimize that "skipping stone" effect, and let the water wrap around the rail rather than release cleanly off the tail. Letting water wrap around the rail will allow you to sink the tail more easily. I like to say, "Flat likes to stay flat... round likes to roll." Round rails will roll over easier than rails with flat bottoms and edges.

    Increased tail rocker. Again, flats work great in flat waves... curves work better in curved waves. You won't get that "skimboard across the flats" feeling between sections, but you'll be able to tighten the turning arch once you get it on a rail. You'll also lose that early takeoff effect because a flatter tail rocker will engage the wave's energy earlier than a curvy tail rocker. More tail surface area also engages wave energy earlier, so a wide flat tail will take off easier than a narrow, rockered tail... all other design elements held constant.

    Fins. Double foiled, straight ahead, and no cant will create no lift, but engage earlier in a turn sooner than... single foiled, toed and canted, which will require a higher angle of attack before they engage, but create lift. This is kind of off topic, so... whatever....

    Deep swallows. Now you've made your mini Sim a fish... but... They allow you to keep a wide, parallel outline through the middle that extends through the tail for trim speed, but provides a lot of release down the stringer. This lets you sink the tail rail on a turn more easily, and, depending on the geometry of the swallow, can add some projection through the turn.

    Just ride the thing... and report back!

  7. #7
    Join Date
    Dec 2008
    Location
    MB 07750
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    345
    looks a lot like Paipo board

  8. #8
    Join Date
    Sep 2009
    Location
    Norfolk, VA
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    396
    Quote Originally Posted by mitchell View Post
    Ray,

    What length are your two boards....with the 4.5" and 2.75" NR? I shaped a 5'5" a couple years ago that only had about 2.5 - 3" nose rocker, and had the same experience...in small mush it worked well, once the waves had any kind of pocket, the board didnt really fit, plus it was a retro fish with deep swallows/keels so that tail didnt make much sense as a grovelor anyway.
    The length of both boards is 6'0" and while the nose, mid & tail width are within an 1/8" of an inch of each other (20"N x 23"M x 20"T), the outlines are very much different. The "performance" oriented one (pics below) shows the planshape curves & huge concave coming out the back. This one actually has a 5" NR, with almost all of it in the first 12".

    Unfortunately, I don't have any pics of the fatboy, but the rails are super straight. The thickness is also carried out to the tail, making it almost twice as thick as this one. Definitely not the ride of a fish. It should be good for the knee-high winter waves in soaked, full rubber...that's why I had it made, anyway.





    Last edited by Ray F.; Jun 13, 2011 at 02:04 AM.

  9. #9
    Join Date
    Apr 2011
    Location
    OC MD
    Posts
    21
    looks real fun dude, how stable is this shape compared to something like a retro fish?

  10. #10
    Join Date
    Aug 2010
    Location
    Kenai Peninsula, Alaska
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    469
    Quote Originally Posted by GnarActually View Post
    if you don't know, you can't ride it
    hey gnar, actually mitchell (along with ray and lbc) is one of the most knowledgable and well-traveled - not to mention chill - people on here (and i don't even know him). you might want to rethink your approach...