View Full Version : Deboichet stiffnes index

19th March 2007, 08:56 PM

Dear All,

a simple question about Deboichet fins stiffness index:

how to interpret -- (minus, minus) signs ?

In other words, a S-- fin is stiffer or softer than a simple S one ?

Many thanks.

- Expander.

19th March 2007, 09:14 PM
Hi Expander,

A Soft -- is softer than the soft.

All the best

19th March 2007, 09:49 PM
I've never been clear on how to measure rake. Can you explain rake for me?

19th March 2007, 10:54 PM
Hi o2bnme,

3 Years ago their was only on rake, and Deboichet decide to mesure it like this :

From the original rake, you mesure at 68cm from the base and he reduce the angle by + 1 to + 12cm (vertical).

All the best

19th March 2007, 10:57 PM

Thank you, Remi, for very quick reply.

So, if suggested 161 fin (R19) with rake +8 and stiffness S-- should be used in light to medium wind (from 7 to 15 knots) and not over, I wonder if same fin rake +6 and stiffness S could be used from 15 to 20 knots.

R13, instead, could be used only over 20 knots.

In other words, what do you think of this 161 fins quiver:

from 7 to 15 knots: R19 +8 S--
from 15 to 20 knots: R19 +6 S
over 20 knots: R13 +6 M


20th March 2007, 01:03 AM
Hi Expander,

This is what I use right now :

Under 15 knots : R19 soft -- rake +8cm

Over I use R13 soft rake+ 8cm you accelerate more with the R13 profil in this condition compare to the R19. I prefer the soft one, you get more lift with it and very good also in extrem choppy water and waves.

The R13 medium rake +8cm, I like it also but from 16 to 20 in flat water, but with only 2 fins I am perfect.

All the best

20th March 2007, 02:43 PM

Thank you Remi for your infinite patience.

At this point I wonder what could be field of utilization of a R19 +6 S; in other words: when to use or who could use it?


- Exp.

20th March 2007, 04:13 PM
Hi Expander,

If you have to order it, go definitely to the R19 soft -- rake +8cm or 6cm but not the soft one, it's too stiff. It's not a bad fin but the soft -- is a lot beter under 15 knots. And over 15 knots the R13 profil is beter due to less drags.

All the best

23rd March 2007, 04:58 PM
Hi Remi,
what's the difference between R13S+8 and R17S+6 over 16 kns (on 161) ?
I find the R17 very fast in that condition but it put me in trouble when it gets lighter.No way to keep a good angle if not very good powered up from sail....
I think that the R17 should work fine since 13-14 kns to 25 kns (but with 11,0 or 10,7,not down) .
Just my 2 cents

23rd March 2007, 05:08 PM
Hi G,

You right for the R17 soft rake + 6cm, it's a fast fin in stable wind over 16 knots to 22 with a 11m particulary down wind, but prefer the R13 profil who give me a beter instant acceleration and angle and make an important difference in unstable wind condition and also on a start line.

All the best

23rd March 2007, 05:46 PM
What you mean when say "unstable wind condition" ?
16-22 is a huge range so "unstable" should be bigger.Am I right?
Plus,doesn't the r17 come straight away from r13 profil (being larger on the tip)?
Another question is:
how a r13m+5 moved forward in the base (making bigger the distance of the chord from the end of the board) will behave in 161?
It's one of my old fin....

23rd March 2007, 05:56 PM
Hi G,

Even over 16 knots you can have unstable wind condition in direction and force in this case the R17 loose a bit compare to the R13 up wind only, down wind it's still fast.

I am using the R13 m at +8cm and love it, so you can change the angle for your old R13 to make a new good machine for your F161. Never try on this board a fin more forward in the box. Normaly we do this when we get spin out and I don't think so it's necessary on this board. But try it and let me know.

All the best

23rd March 2007, 06:03 PM
Infact I had this problem in last season board....
Unfortunally now it's impossible readjust it without loosing some cm and I don't want to.
I'll try it and I'll let you know.
I couldn't try the r19 purchased fin too (lot of wind so far) . Any advice on it (not the custom one,just the purchased) ?