|3rd June 2008 04:47 AM|
I get your point. At least the dialogue on these forums will have to continue explaining the system from time to time.
|2nd June 2008 11:04 PM|
funny thing about mental 'lock-in' - I somehow doubt that (at least Deboichet) will change over to something more 'rational.' Think QWERTY keyboards - those were designed when the first mechanical type writers were built a long time ago, with the goal of slowing down the typist (by making her hunt for keys in unexpected, out of the way locations on the keyboard layout) so as to avoid jamming the (at that time not very robust) type writer mechanisms (those little levers with the type stamp hitting against the ink ribbon would otherwise get caught up in each other). Now that this constraint no longer exists (and hasn't for several generations of touch-typists...), one would think we'd have gone to something like the Dvorak keyboard (or something else that was designed to SPEED UP typing, rather than slow it down), but once something is "the standard"...
|30th May 2008 11:36 PM|
Thanks guys, I now get it. It seems like they should make a change at some point to a more logical measuring system.
|30th May 2008 10:33 PM|
Yes, you are right, 90 degrees to the board is vertical, however Deboichet uses a scale that doesn't refer to angles or vertical at all; it can be a little confusing!
I don't know exactly how it came about, but basically back about 4-5 years when everyone started changing the rake of their fins to be more upright, Deboichet fins were about the only decent fins on the market and so people started saying "my fin is +2 or +4cm", which meant that their fin was 2cm more upright than the "original" fin was designed.
Eventually, this became a little more standardised (thank god!) and the popular Deboichet system used now is +11cm as vertical (although most fins are usually +6cm or +8cm) which is just a reflection of how far the fin is raked upright compared to the "original mould". Its a confusing scale as it doesn't reflect AT ALL how "upright" the fin is. It merely refers to the original rake on the fin mould (although this has somewhat changed over the years).
I prefer to talk in degrees where 0 degrees is vertical and 2.5 degrees is roughly a +8cm Deboichet fin (or 30mm back from vertical at the tip) as this is less confusing. The Deboichet rake system only applies to Deboichet fins!
I just mentioned the 30mm back from vertical just to show you that this is what is considered "+8cm" right now, as I'm sure if you have a Deboichet fin from 4-5 years back it might not be the same "original rake" as a fin that is made now.
Does that make sense?
|30th May 2008 02:51 AM|
the measurement of the rake is for some reason "inverted": a higher number means a more upright leading edge, and a lower number a more raked fin.
I was a bit confused too, but there's a wonderful article on carbonsugar.com about fins and fin-related measurements that explains everything. Really worth a read.
|29th May 2008 10:39 PM|
Great information, Thanks a lot. However, I am a little confused by your statement:
"A Deboichet fin at +11cm is raked at vertical. So a fin at +8cm would be 30mm from vertical".
How is +11cm vertical? Wouldn't vertical be +0 (leading edge at 90 degrees from the board)?
|29th May 2008 01:33 PM|
@ Unregistered - If you are mostly sailing in >10 knots, I would go with the R13 S--. In flex-stiffness, the R13 will be considerably softer than the R19 because the foil is thinner and has less area. The R13 is a very versatile fin and works in nearly all conditions and requires minimal tuning from the rider to get up to speed.
Remi is right, for lightwinds the R19 would be better, but if you were only going to buy ONE fin, I would think you'd get more out of the R13 across the different conditions. Make sure you go for an S-- as in the 160 it really appreciates a soft fin for power. This will be suitable even in strong winds and you still have your R13M if you prefer that as the wind gets up.
@ Ken - put your R13M in your board and put a straight ruler at the front of your fin from the bottom of the board perpindicular to the board. With another ruler, measure the distance from vertical to your fin tip. Like this photo: http://www.carbonsugar.com/wp-conten...08/04/rake.jpg - although, measure the TIP not 15cm down from the tip like in this photo.
A Deboichet fin at +11cm is raked at vertical. So a fin at +8cm would be 30mm from vertical. +6cm = 50mm from vertical etc etc. That way you can find what rake your fin is regardless of its vintage.
You can change the rake a little by sanding the front/back of the fin head and kicking it forward in your finbox but changing the rake anymore than 1.5cm requires you to drill out your fin bolt holes in the fin head as they will no longer line up with your board holes.
There's some more info about what rake and stiffness does to fins and to your boards in an article I wrote here if this helps:
|29th May 2008 05:01 AM|
Thanks for you response. I may check with Bruce, but it was more curiosity than anything. I have been happy with the fin, but wondered what the difference was between my fin and the R13m +6 that Remi suggested for Tomek since I weigh 79 kg and also have a 160.
|29th May 2008 02:15 AM|
give Bruce a call at the Sailworks loft (541-386-6561); he'll be able to tell you. There was the old 'standard' rake (the very first R13's), which became the basis for all the +x nomenclature. Then at some point (and I believe that was right around the time you're referencing - around 04 or 05), the "standard" rake for new R13's was changed to something like +2 or +3. I remember having a conversation with Bruce about it, so I'm sure he'll be able to tell you.
|29th May 2008 12:38 AM|
I have an R13M, which I bought about about 4 years ago. I got if from Sailworks and didn't know anything about rake at the time and they didn't offer any information. I don't know what the rake for this fin is. I guess it was the standard rake at the time. Can you help?
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