Ok, now that drive has been “defined”, here is another term that I’m not sure we’ll all agree on; Release. Release; to let go. That was easy! In surfboard design I’m assuming that it means to shead water in the most efficient manner. Sharp edges allow water to “release” from the bottom of the board or rails easier than a curved surface which allows/forces water to adhere to the surface. The same goes for fins. My confusion is when the release is used as a performance term; “The thruster set-up releases better off the top than a single fin.” I never hear the term used in describing a bottom turn.
I envision release to mean the ability to change edges or rails quickly without losing too much momentum or velocity. Why would three fins flapping around under your board release better than one? Depth of fin? Shape of the fin? Both?
A few observations about release off the top. I have found that three fins (thrusters) release off the top better than quads or singles or bonzers. I have also found that boards with more tail rocker release better off the top.
So… I think that it has to do with depth of fin, total fin area, and distribution of fin area. I think that singles don’t release as well, off the top, because the fin depth is long, and the tail rockers is usually low. So as the rider transitions from a more weight-back positon to a more weight-forward postition the fin is still engaged. Quads don’t release as well because they have more fin area than thursters. Thruster release well because they have less fin area, lower fin depth, and more rocker, so as the rider shifts to a more weight-forwoard position the fins come out of the water easier.
I don’t know why you would want release on a bottom turn, I want control, drive and speed.
I hear the term release used in at least two seperate contexts. One is the off-the-top, the other a more general use that describes a skatey feeling.
In the case of the off-the-top, I (and others) have done the add-edge/take-off-edge trialing and found that crisp tail edges release better. The slight squareness you see in tail rails of modern shortboards seems to function well in terms of this release also. Getting the rocker/rail combo just right inthe last 18'' is the key.
Higher volume boards with crisp edges in the tail (or overall) exhibit the second, more general context. The trade-off is loss of sensitivity and the ability to overpower the board in critical maneuvers and recoveries. To each his own....
I'll take sides with Mike Daniel. "Release" is often used in more than one context.
In that book by Lindsay Lord (Naval Architecture of Planing Hulls) there are descriptions of hydrodynamic steps and flat surfaces with hard edges 'releasing' water more efficiently than a soft, rolled, radiused corner. That is one type of release, in which the water flow breaks away from the surface of a planing hull. There are diagrams of the transom of different boats illustrating this type of release.
Also consider the outside surface of an asymmetrically foiled side fin (typical thruster)... I'd like to think that the foiled surface of the outside fin 'releases' as the board is banked and the flat surface of the inside fin engages. I'm open to correction from any of the fin experts out there on this but IMO the flat surface of the inside fin tends to grab while the foiled outer surface breaks away during a turn.
I'd also suspect that a thin railed and/or concave decked board would tend to be more difficult to release off the top while a dome decked fat railed board would 'release' more easily. The thin rail allows more water over the deck which inhibits the ability to make quick edge changes. Again, hull afficienados or others feel free to correct me on this.
Of course vee, roll and other features might be regarding as elements that allow some degree of 'release' in one aspect or another.
Proneman's version, if I understand the context, is of a more emotional variety and equally valid.
I agree with Mike Daniel and John Mellor about the two meanings of release, I think the reason why we are not arguing like on your drive defined thread and its spinoff the what creates drive thread is because the context of the 2 situations (off the top V board qualities that reduce drag) make the dual meanings clear. We have 2 clear contexts instead of many fuzzy ones. If we can understand the different drive situations better then I’m hoping we will be able to use context to understand each other when using the word drive too.
Anyway time for me to re-enter the fray on the drive threads…
Any V will increase drag. It will cause the tail of a board to ''settle'' deeper in the water. That principle is what made the old hotcurl design work. The increased drag stablized the board, and gave the rider greater directional control.
The tracking effect of a narrow vee as in the hull of a Hot Curl design is obvious enough but other factors might be considered, especially with a milder form of vee on wide tailed multi-fin boards during edge change maneuvers on the steep face of a breaking wave.
Tank testing of various shapes that may show the efficiency of a flat planing surface are valid. A surfboard is a more dynamic shape that with input from rider may engage various sections of a board's shape with wave surfaces that differ from a hull test in a test tank.
Assuming the inside rail is buried and the board is banked on the inside of a vee panel in a turn up the face, will suddenly banking to the opposite vee panel help break free (release) the buried rail as the opposite rail is engaged? Would that reduce drag on the formerly buried inside rail/deck in an off-the-top maneuver?
Would such a maneuver possibly allow (after a subsequent edge change) a smaller, hydrodynamically efficient portion of the board (I.E. rear third edge) to engage with a steeper harder breaking section of the wave and result in:
I have found the same with my midlength. If i surf it as a thruster, it flies off the top, but with a 2+1 setup, it can hang. With the thruster setup, the back of the centre fin is 8'' from the tail, so that may have something to do with it. Also, i have found that a smaller centre fin, and larger sides ( in a 2+1 setup ) gives good release, but still has the drive i want from the 2+1 setup.
**Release** is the re-establishment of
optimal planing conditions though changes in bottom presentation.
How you bring it about or enhance the
process of bringing it about varies, but it will more than likely
involve changes in the posture and stance of the surfer.
There has also been little mention
about why you'd find yourself in need of release to begin with. (Wow, that's a statement waiting for a reply if there ever was one.) Which is understandable, as that wasn't the question. Still, if you buy into my definition you've got the whole package - something was lost, then recovered, or just saught initially - the final net sensation being that of release, given the context.
Anyway, glad MrJ, Thrailkill and you, and less explicitedly, obproud, introduced the role of
I find thin rails destabilise the board so it goes rail to rail much easier. I think this has less to do with release than weighting the rail easier.
I find that a bigger trailing fin helps off the top, but I think this is because of the improved power transfer (drive?), rather than release. I’ve had plenty boards that hang up in the lip - eliminated through conbo of tail kick and larger tail fin (a G5 over a G3000, say)
Could there be a third aspect to release - the opposite of when concaves or channels suck to the face?
"I find thin rails destabilise the board so it goes rail to rail much easier. I think this has less to do with release than weighting the rail easier."
Actually, that makes sense to me. I'd have to rethink what I thought before... about water over the deck. I know some of the SUP designers are purposely shaping a forward domed vee deck to shed water in the event of pearling while downwinding or catching chop over the deck. That theory and my own experience is what led to my former conclusion that water over the deck inhibited rail to rail transition. Being able to sink a thin rail more easily thereby releasing the other rail also seems reasonable.
The idea of tail kick eliminating hang up in the lip makes sense too. I.E. less board in the water allowing easier direction changes by creating a shorter 'wheelbase.'
I always thought concaves (of certain configuration) provided lift which secondarily reduced drag or provided release but I'm open to explanation on why they would suck to the face. Maybe one of those situations where what applies in the test tank (or faucet test) doesn't apply to the real world?
My very first board (transitional Morey-Pope 'Deese Original') had a strange deep forward vee. I always felt that by leading in to a turn on the inside forward rail that I was somehow releasing the tail area. The board had a fairly flat nose rocker and it felt as if rocking forward on one side of the forward vee panel released the tail. I remember that at times, with the flimsy plastic fin that board had, that I could spin it out. When it wasn't spinning out, it sometimes felt like I was releasing the emergency brake.
It was my first board and I was definitely in the steep part of my learning curve.
er sorry, I wrote that rather ambiguously, I meant the character 'v' as in the abbreviation for "versus" not hull V (which is an obvious interpretation to a board builder!) and even my choice of the word "versus" is not good english as it normally referrs to two competing entities whereas releasing off the top and reducing drag (which is what release edges do I believe) are two completely different things.
What I meant to say was:
"releasing off the top" and "release to reduce drag" are mentioned in such different contexts that we don't get the two mixed up when posting about these things. Nevertheless you have introduced a good point of discussion:
..That principle is what made the old hotcurl design work...
the hotcurl is an extreme shape (deep V) and I also think that studying extreme shapes can be a useful tool for understanding board qualities in their more subtle form eg. it wasn't until I rode an extreme opposite of the concave bottom that I really understood just what subtle concaves were doing for me - it became clearer when I rode the McCoy nugget which i consider to be in the extreme shape category for its use of deep roll - (which its maker calls the "loaded dome"). a lot of my self-built boards have been in the extreme shape category - this condemned them into never making the magic category, but greatly increased my understanding of the shape.
The point that I was hoping to make is
that it's not the board or any given design element. A good overall design, or maybe just the addition of some single design element for a given set of
conditions/surfer can facilitate release.
As for 'roll over', if I interpreted
what you meant correctly, that's worthy of its own thread. But given
the 'thrust' of this thread, and my reluctance to 'tome it up' I'll
keep my reply short.
Though most (me included) think and
draw pictures that seem to take into account the upward velocity of
the flow in a wave, the forward velocity is usually sacrificed for
clarity sake -i.e. the perspective is one of an observer moving with
a forward velocity which matches that of the wave. Yet this forward
flow is also contributing to planing.
Unlike a deep water wave form, when
shoaling/breaking the face of the wave is no longer moving at a
constant speed (as you move alone its crest.) The curl region is
constantly falling behind relative to the shoulder, or decelerating
relative to the shoulder. Surfers move into and out of these regions
all the time. But, if they stay in a given region for any length of
time, they must match, on average, the speed and any changes in speed
of that region. Otherwise, their motion in the direction of
propagation is less than that of the wave, or it's greater, that is
they're getting too far out in front of the wave form. Both states
will impact planing, as both states will partially define the
relative flow experienced by the board.
Curiously, if your using one of those
wave-simulators (as in the stationary kind - basically, a lot of
water is sent over a hump or some structure - I think they put them
on cruise ships now) or river surfing, etc. you eliminated this
variable [forward flow of the wave face]. You're still surfing, or
utilizing planing, but what is optimal changes. In fact it would be
nice to read a river surfer's comments about 'release',
particularly if they can make a comparison to ocean/sea/lake or wake