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Old 26th April 2010, 04:36 AM   #1
ChrisN
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Question iS144 WC plan earlier than a iS144 Wood - How many knots earlier?

We have been debating this in another thread (see link) for some time now, but have not received any answer from SB's Team!

Both in these Forums and Website, SB is marketing the new construction with a lot of statements about the "premium" WC construction. For example:
  • In a thread less than a Y ago, IAN FOX mentioned: "The Futuras (and iSonics) can definitely be made lighter in Wood+Carbon tech, which offers an advantage in earlier planing in lighter winds and on flatter water."
  • In the presentation of the iSonics and Futuras, here is the statement: "WoodCarbon offers the lightest weight of all with a stiffer construction that offers quicker acceleration in lighter winds."

What I've been asking is that if I use the same sailor (advanced skill) with the same sail (e.g. 10 m2 OverDrive/NP V8/etc.) and Fin (e.g. 520) in the same conditions (e.g. flatwater with chop), which of these 2 board will plan earlier? By which margin?

Please share some of your test results (even informal), as it then makes sense to invest the 200Ä difference on a WC board rather on the Wood one...
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Old 26th April 2010, 11:30 PM   #2
ChrisN
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On the WC vrs. Wood construction, many forum contributors well versed in light-wind planning, mentioned that such constructions have low/ secondary significance to Width and Fin length. Broader boards can "carry" longer fins which then may help to reach earlier planning!

While most of SB's previous Formulas were in Wood, the new ones are in WoodCarbon, because as SB states: "After thorough tests between pure wood technologies, pure carbon technologies and two variations of a new Wood Carbon hybrid technology across various wind, water and rider conditions, Starboard chose the hybrid WoodCarbon technology ..."

The competition is also moving towards Carbon-based construction in Formula boards, like JP's Formula 100 PRO. JP states: "The full Carbon Deck of the Formula 100 has already proven to be the best construction on the market for lightwind Slalom boards. Antoine believes that this construction gives the big JP Slalom boards the edge over competition boards.
This is the stiffest and most rigid construction available today and provides big advantages in early planing and staying on a plane around the marks"!!

Thus, SB and everyone else agrees that Carbon or WoodCarbon versions enable earlier planning! The same argument could be then be made for the iS144 and iS150 (latter only available in Wood ).

So, are there any documented effects of WoodCarbon construction in e.g. iS144 in earlier planning?
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Old 28th April 2010, 08:11 PM   #3
ChrisN
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To add some more facts on the table about these comparisons of Construction Effect on Performance, I am going to quote from the Test the respectable German SURF magazine conducted last year (july 2009). The article are available for free as a PDF File, so Iíll just summarize here [my translation]. The boards tested were:
  • Fanatic Shark 145 LTD vs. HRS
  • JP-Australia X-Cite Ride 120 Pro vs. FWS vs. ES
  • Starboard Futura 122 Wood vs. GO-Tuffskin
  • Tabou Rocket 125 LTD vs. Normal version vs. GT

SURF tested the different constructions with identical rigging and found in spite of the same Shape there were significant performance differences between the light- to the heaviest-weight boards. One may not expect that the heavier Board feels as agile as the lighter Board. Rather it feels a bit slow-acting, more full, release slower, with less acceleration! These were matching results across all comparison tests. Not only professionals can gain from the lighter constructions, as intermediate sailors may profit from earlier planning abilities.
Lightweight constructions have a definite advantage on upwind, as they wobble less and with fully loaded fins tend to stay planning. In maneuvers there is almost no difference, yet the Lightweight versions of Tabou, JP-Australia and Fanatic ran quieter, planned earlier and steered easier through choppy conditions. See the comparison of the Fanatic Shark 145 - the differences are really evident in Planning through Lulls, and Speed in mid-winds (=reaching higher speed in lower winds):



In summary, top construction brings a bit more fun not the very good surfers. Durability and also the controllability certainly do not suffer from the lower weight. In ALL tests the lightweight constructions outperform the heavier ones!

From the above our question to SB's Team still stands unanswered:
how much quicker does the iS144 WoodCarbon plan compared to iS144? Wood?
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File Type: jpg Construction - JP vrs Taboo Constructions.jpg (23.1 KB, 11 views)
File Type: jpg Construction - Starboard.jpg (28.8 KB, 12 views)
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Old 28th April 2010, 08:52 PM   #4
Maximus
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Mate

I suggest you buy the wood, cause the carbon option wont make any difference for you!
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Old 28th April 2010, 10:24 PM   #5
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I love how you've really taken this topic to heart, ChrisN. Maybe SB will reward you with an answer one of these days!

But I think what you're looking for is a documented proof that WC will plane fast than Wood. It's pretty obvious that WC will plane earlier (explained by basic physics), but by how much remains to tests to tell.

Basic physics, Newton's second law: Force = Mass x Acceleration

Force: Forward force of sail - drag (air resistance and board/fin skin friction in water)
Mass: Mass of total observed object (kit + rider)
Acceleration: Rate of change of speed

Keeping force constant, as mass decreases, acceleration must increase and mass will be decreased by using a WC board over a Wood board. This is quite far-fetched, as the mass being changed is very small relative to the total mass, but does remain true. On an even more far-fetched level, increased mass of board will decrease total forward force/increase drag as the board will sink further into the water, creating more skin friction.

Just thought I'd put this out there, and it's good revision for my exams in 2 weeks....
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Old 28th April 2010, 11:37 PM   #6
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An extremely simplified example of just how insignificant the weight "advantage" is in a WC board over a Wood board could be:

Mass = iSonic 144 Wood (7.79kg) + Rig (let's say 9.0kgs) + Rider (70kgs) = 86.79kgs
Acceleration = 3m/s^2 or roughly 6knots/s^2

Obviously acceleration will be greatest in the beginning when the skin friction is lowest due to lowest velocity UNTIL the board starts planing at which point the total forward force increases due to less friction. Because of all these variables, we can just look at what happens in the first second, regardless of planing/not planing. The board goes from 0 - 6.0 knots in 1 second

This means that the force (ignore units as we are working in knots and not m/s) is
86.79 x 6.0 = 520.74 units of force

If we now take an iSonic 144 WC with the same rider, and same force, the mass has changed by 7.79 - 7.14 = 0.65kgs

The new total mass with a WC iSonic 144 is now 86.14kgs

So now, for the same forward force our acceleration must be

force/mass = 520.74/86.14 = 6.05 knots per second^2

I don't know how valid a reasoning this is to show that indeed weight gain between WC and Wood is not a very important factor in affecting acceleration/early planing (as both are very closely linked).

This somewhat reinforces what someone said in the earlier thread about stiffness/width playing a much more important role in early planing than weight.
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Old 28th April 2010, 11:47 PM   #7
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At .65 kg (1.4 lbs) difference between the WC and W 144, there will be no noticeable difference in planing threshold - In my opinion.

For the German tests to mean anything, we need to see the weight differences between boards to evaluate fairly. Also, the differences in stiffness is equally important and I suspect that the differences between the test boards is significantly greater than between the wood and wood/carbon Starboard boards.

No doubt that most advanced sailors will be able to tell that the wood boards will out perform the Tufskin boards, but it is because of the significant weight and stiffness differences.

For example. The Futura 141, the weight differences between the Wood and Tufskin models is 2.02 kg or 4.4 lbs. Include the greater stiffness of the wood model and you will find a somewhat higher level of performance for the wood board.
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Old 29th April 2010, 01:43 AM   #8
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Lightbulb

Agrelon, this is really an interesting estimation formula! Even if as you state it is neither complete nor validated (I'll get my Naval Engineer brother to check), it proves that it's not Weight per say but rather the stiffness/rigidity of the same board shape in a lighter versions that get SURF's testers to give the Carbon-based constructions higher points in "Planning Ability" and "Planning through Lulls", "Top Speed", "Reaching Speed in lower winds" and "Upwind Ability". ALL tests have shown that the Light-weight constructions are faster and easier to control than their variants. If you see the Taboo and JP ones, the differences from heaviest to lightest constructions are very pronounced.

To summarize many of the posts so far, a formula for Light Wind Planning (LWP) potential should consist of at least the following parameters. As higher the LWP as lower the wind acceleration commencement point in Knots. Thus, a simplified version of our conversation in prioritized rank could be expressed as shown below (i.e. SKILL is more important than FIN for earlier planning):

LWP = SKILL*c1 + WIDTH*c2 + FIN*c3 + RIGIDITY*c4 + SURFACE_DRAG*c5 + VOLUME*c6 + (1/WEIGHT_BRS)*c7

Explanations:
  • WIDTH: this is the width of the board; More Width leads to higher LWP
  • FIN: Fin length - longer fin means more lift and higher LWP
  • RIGIDITY: lateral and lengthwise stiffness/rigidity of the shape, outline and edges translates in quicker release; More Stiffness leads to more LWP
  • VOLUME: As the Volume increases (to a point) as higher the LWP (not sure but it counteracts the WEIGHT parameter)
  • SKILL: More advanced sailors will pump more efficiently thus releasing the board earlier, so higher LWP.
  • WEIGHT_BRS: Overall weight of Board, Rig and Sailor which inversely affects LWP.
  • SURFACE_DRAG: Deep Double Concaves and other gimmicks to minimize the wetted area and tractions, contributes to quicker release or keeping the planning; Lower Drag leads to Higher LWP.
  • All Constants (C1-7) will have different thresholds, that should control the range parameters will be effective on LWP - e.g. beyond a certain stiffness there is no more effect on LWP.
Now we just need some DATA! Surely Jim Drake and Tieda You have made these kind of engineering experiments (and even tested some of them). They could enlighten us amateurs

Our question presumed that beyond RIGIDITY and WEIGHT_BRS we were keeping all other parameters constant/same, and we were asking the effect on LWP (recalling the higher LWP meant lower knot-threshold for planning).

PS: Good luck with your exams
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Old 29th April 2010, 05:15 AM   #9
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Hey SB, what's up ?

Hibernation ? Ash clouds ?

You can't leave ChrisN out in the cold, especially after his wonderful analytical elucidation.

We all want an answer now.
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Old 29th April 2010, 01:51 PM   #10
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Quote:
Originally Posted by ChrisN View Post
[FONT="Tahoma"][SIZE="2"]To add some more facts on the table about these comparisons of Construction Effect on Performance, I am going to quote from the Test the respectable German SURF magazine conducted last year (july 2009).
There was actually a much more comprehensive test from BOARDS UK (in 2008 I believe) that failed to show any difference in performance between identical boards with different (standard vs LTD) construction. They compared JP, RRD, Mistral in the 75-85-100 and 125 categories, and found small differences only with the biggest boards, but those boards (mistral) turned out to have also a difference in rocker that gave an unfair advantage to the LTD construction.

If you consider that a slalom boards sails overpowered, I doubt you could tell any difference for 1-2 pounds of weight, maybe more. It is easy enough to check by putting an extra 1Kg at the mast base.

Last edited by davide; 29th April 2010 at 01:55 PM.
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