anyone know why FCS advise the below for boards with more rocker ?
more drive to compensate for the drag caused by the rocker would be my geuss. I fiure if you are riding a board with more rocker you are going to be able to over power smaller fins and you should stiffen up the board. just a geuss, hopefully some one like Bill Barnfield or Blakestah will chime in with a more accurate answer
Aloha
Boards with a lot of rocker allow water to release off the bottom easier and present a less resistant platform for the rider to press against.
Consequently, the board won’t push back or resist as well as a flatter rocker would. Because of this, you may find that you want to gain back some of the lost resistance and since you can’t easily flatten the rocker you can add fin area to increase the resistance. Typical Channel Bottoms have the opposite effect and require less fin area because they don’t release the water easier.
This is all a good example of why custom boards are preferred by advanced or knowledgeable surfers. Once they know and understand the typical forces that they use in surfing they can more easily create the right board to accommodate those forces, rather then going on the endless search to find one randomly in a rack full of “stock” boards or “models”. Of course, it can often be just as frustrating to try and find a “personal” shaper that can or will tune into your needs and express them properly into foam.
Every surfer pushes his board to some degree. And they expect that board to push back to some degree. It is the skill of the shaper/designer working with the surfers input, that will determine the subtle blending of various features in the board that balances these forces. The mastery comes in continually increasing the positives and effectively decreasing the negatives such that each board is an improvement over the other while keeping pace with the evolving abilities and expectations of the surfer.
Fins are a huge part of striking the right balance and the FCS advise is accurate. ProBox takes this all a big leap further by allowing one to not only change fin templates but also fore and aft positioning and Cant. When trimming, more Cant can help lift the board and improve speed but too much will allow excessive release off the inside fin when turning and reduce resistance.
There are no absolute rules here. Rider experience and satisfaction is the primary goal. Daily conditions can change and having access to spontaneously changing certain design features is a fantastic way to accommodate varying surf conditions.
thanks bill. however, gets me thinking: why not just use a flatter rocker in the first place ?
More rocker works better in steep sucking waves. The boards fit the tighter curvature of a hollow wave. They also drive off the rail for tight radius on rail turns.
Typically, if you are shaping a board for softer surf, you’ll design the board with less rocker, more concave, more tail area in the board and more cant in the fins to maximize lift and minimze drag and keep it loose. If you’re designing a board for more power you’ll go with more rocker, more vee, less tail area and less cant in the fins to maximize control.
Now, if you are using this higher rockered board in fast waves as opposed to quick waves. Smaller highly efficient fins will work just fine. The higher flow rates allow more efficient foils more control to use that rail with. If you’re planning on surfing in quick conditions, a larger template will give you more to push off especially in flat or concave inside surfaced fins. So, it depends on what you’re trying to optimize for.
Quote:
thanks bill. however, gets me thinking: why not just use a flatter rocker in the first place ?
Good Point
But the original issue was regarding an existing board that needed some tweaking to make it work better because it might have had too much rocker and the fin adjustment noted by FCS was a viable solution to help improve it.
But… if one was going to be designing a board from scratch then, as you have wisely noted, having the correct rocker for the boards general use and rider, is essential. Once the board is built there are limited things that can be done to “tweak” it enough to make a really bad board suddenly excellent.
Once again, this only affirms the reality of getting the right board through the custom built process. Still, I have to qualify this by saying that probably only around 25% of surfers will directly benefit from this enough to make it worth them going through the trouble. For the other 75%, having a rudimentary understanding of boards and waves and what one is trying to accomplish in their surfing will allow them to safely purchase a “stock” board from a reputable retailer with knowledgeable and responsible salespeople.
This brings another issue to mind. Surfing, as we all know, attracts a vast collection of highly independent, often unique and eclectic characters. And the art and industry of surfboard building seems to filter this already curious group of characters into even a more aberrant and often unaccountable potpourri of craftsmen.
Among these then, there always seems to be an inordinate amount of flakes, scammers and quasi businessmen that function in ways that the average consumer wouldn’t and shouldn’t expect. Consequently, this raises the risks of shopping for a “custom” board to a level higher then many want to deal with and can often make an in the rack, “stock” molded board from Asia, look like a simple, clear and attractive choice, even to those who probably should be looking at riding “custom” equipment.
Keep in mind that the 25% I was speaking about are not necessarily the best surfers in ability. Though that will help. They may just be people who are more sensitive about details, more analytical and calculating about what they want and what their bodies feel when they do things. For them, there will be greater satisfaction knowing they have customized the “right” board for themselves, regardless of whether or not they can push that board into the realms it is actually capable of.
PS. Tom’s comments in his post were right on.
Quote:
anyone know why FCS advise the below for boards with more rocker ?
the archives are ever illuminating
This, not exactly the same, but related thread, with comments from Burger and the genius
http://www.swaylocks.com/forum/gforum.cgi?post=158115
hth
thanks guys for the replies. i ride a 6’ 2" …lost whiplash board. been trying lots of fin combos and templates and all the options are doing my head in !
why would a board such as a retro style singlefin, with very little rocker, need that larger fin then? Is it because that’s the only place where all that fin area is able to be distributed? versus something with three or four fins ie. where the area is distributed throughout all multiple fins? or does it have to do with something else? or am i missing the point…
Aloha JDM
You are correct. Surfing requires a certain area of resistance to hold (resist) the board and riders forces. The total fin area must be sufficient for the task, regardless of whether or not the area is contained in a single space (fin) or multiple spaces or fins.
This is a simplified description of the problem so that the issue won’t get too complex and will remain easier to grasp.
Remember this principle. Board design features are generally either energy absorbing or energy shedding. More energy absorbsion creates more speed. More speed has huge advantages as long as the increased speed and energy is controllable.
Highly rockered single fins never worked very good. (but then neither did too flat of ones either)
Single fins couldn’t have too wide of tails because they would easily get out of control in more powerful surf or even spin out on heavy turns in smaller surf. Wider tails are hugely energy absorbing. Narrower tails are energy shedding. Less rocker is energy absorbing, more rocker is energy shedding. Bottom contours can alter this a bit, but I am trying to keep this simple for the sake of clarity.
Since single fins had narrower tails, when we increased the rocker, you got the double whammy of two energy shedding features in one board, and the boards were quite often then… slow dogs.
Could it be fixed by a larger fin?? A too large of single fin makes a board harder to turn.
Now the board is… a slow dog… that also doesn’t turn easily if at all.
When the fin is positioned out near the rail, one can use a wider tail and not spin out. Plus 3 fins will keep the board under control better. Consequently, wider tails that absorb more energy suddenly became possible, even in huge powerful Hawaiian surf.
The game has always been to find ways to absorb more energy while retaining sufficient control so as to be able to use that energy positively by turning it into speed, from which all kinds of cool moves originate.
There is a constant battle between speed and maneuverability. Energy absorbing features, like flatter rockers, often come at the cost of reducing maneuverability. But often the speed gained allows one to maneuver in ways that lower speeds won’t. On the other hand, maneuverability allows one to drive into places on the wave where there is more power stored and as such, absorb more energy and gain more speed to compensate for the loss of speed from an energy shedding feature like more rocker.
Additionally, side fins set up correctly with proper Cant, will help hydroplane the hull gaining lift and extra speed without greater wetted surface and drag.
If you understand the above and I think you do … you aren’t missing the point!
Quote:
…
Additionally, side fins set up correctly with proper Cant, will help hydroplane the hull gaining lift and extra speed without greater wetted surface and drag.
I put forth that the canted fins create the perception of reduced drag not by creating lift and reducing wetted area, but by reducing fin drag by more closely aligning the fin with the water flow.
Aloha BB…I like your energy absorbing/shedding approach to the subject. A great way to simplify a complex concept for laymen. Realistically people need to know while the fin(s) play a large and significant part in a board’s overall performance, changing the fin(s) is rarely a panacea for a fundamentally challenged hull for any given rider.
So in effect, the FCS recommendation should be taken as well studied advice offering improvement and, maybe, but just maybe, a solution in a small ercentage of cases.
Beyond the fin choice option what else can a fella do (or gal) do, short of acquiring a new board?
I have taken boards that were too “energy absorbing” and given them a new lease on life by pimping them with soe cloth, resin and rope. You probably already know where I’m going, but for the geral audience, what you do is hang cloth and bead the tail.
This is achieved by sand the tail rail area (you pick how long you want to modify, but 4" to 12" can make a giant difference dependiing upon length of board. Next you hang glass from the top rail and cut the lap so some spring keeps the drape out from the existing edge (or lack of). Apply resin and hotcoat. Flip the board over once cured (UV works great for doing this if you’re in a hurry). You are now ready to fill in the sprung area for a new hard rail (and slightly wider tail outline…remember a little is a lot in this case).
If you only use resin to fill this area in you will not have a new improved stronger board…I rehab people’s boards using rope for a truly strong beaded tail…you could also use milled fiber or other reinforcing fillers. You could also use Q cell or cabosil but if you want a good looking, very strong tail bead, use well wetted out rope strand and be sure to smack it around on a hard edge (ruler, scissors, etc.) to soften the strands up to allow easier wet out. Then wet it out and lay it into the open crevice.
Then hotcoat and sand out your new tail rail. Use a block for truing and make it as sharp as you dare. You have just added some “energy absorbing” capabilty to your existing board.
If you want to do this in even more a hurry, you can do what we did mid time trials at the California Speedchck (a sailboard racing contest held at the San Luis Reservoir) years back. We used bondo, waxpaper and a block for quickie design changes. It served us well, we got 2nd behind Fred Haywod amongst 308 worldwide competitors.
You would be very surprised at how much you can pick up by beading a tail on a board that has too soft a tailrail, is a little too narrow for what you want, or even has a smidge too much rocker.
Yes, and the modified boards ends up feeling looser (easier rail release, I guess).
To comment on the original question - I think that tails tend to climb out of the water through rail turns in heavily rockered boards. More fin base keeps the board flatter (the outside rail does not lift up so easily). This helps especially in powerful flat waves where heavily rockered boards seem to drift a bit. Just a personal view/observation. I trade Merrick side fins with Occys for flat 4-5’ waves.