View Full Version : Can't find a realy fast fin for my Isonic 105 (2006)

Marc 1964
20th June 2010, 08:25 PM
Yesterday was the perfect day to test some fin's on my Isonic 105 on flat water, good gusts and a perfect trimmed racing sail. The sail that i used was a Gunsails Mega XS 6.2. Well trimmed an with the right 100% carbon mast. The location was Strand Horst in the Netherlands. One of the best Dutch speedspots for competitional speedsailing and recreational funspeeding. There was enough power in the wind to make some good speedruns. I saw some Fanatic Falcon 80's sailing around. Evereybody was realy fast. There was room enough on the water to make good downwind runs. All the conditions where perfect to reach at least 60 kmpu. I was a bit disapointed. I thought that a Isonic 105 was a realy fast slalomboard.

To my suprise and while changing some fin's to find the perefct set-up i couldn't find the best fin in my quiverbox to make realy fast speedruns with that Isonic 105. A year ago i had a Kinetic 58 (2002). That board is much older, much longer (178 cm.) but gave me better speedresults on downwindruns with winds like i had yesterday.

I must say that the Isonic 105 sails far more comfortable, much better upwind, easier to handle in strong gusts and very stable under my feet. But why can't i reach at least the same speeds as i did with my old and already sold Kinetic 58?

To search for the differences i tested my Isonic with two of the fin's that i used for years on my Kinetic 58. Thats the original Kinetic fin 34 cm. and a Select EVO 35 cm. I also tested a F2/Chocofins 31 cm. But that was far too small for the Isonic. The Select sailed the best. The Kinetic fin was very slippery.

My questions are:
1. Can a classic shaped no-nose board go faster on downwindruns than a modern shaped board like this Isonic 105? I hope not!
2. Can you give me some fin-advices to reach the best speedresults on this Isonic. The sails that i use on this board are a 7.4/6.6 and a 6.2 racing sail. Alle modern widesleeve sails.

I hope somebody can give me some good advise to reach better speedresults with this board in these conditions.

21st June 2010, 12:23 AM
Hi Marc,

No SB team here, but a little comment of my part.

The wind has been treating us nicely last week.
I was at the "Brouwersdam" on tuesday, thursday, and today (sunday).
I think we had every day wind between 15 - 25 knots.

I have been using my Isonic101/2009 with NP RS:racing 6.7 and Gunsails Mega XS 5.7.
I used with both sails the G10 Kai Hopf falcon fin of 34cm.
It felt real fast. I'm not a speedsurfer, but I still want to buy a GPS, to find out how fast I go. In the past I have been clocked close to 60 km/h with "old classic" boards and I must say that the Isonic feels faster.

To get into real speedsurfing, probably you'll need to go more for the IS86 and IS Speed Specials.


Marc 1964
21st June 2010, 01:24 AM
That's true! An Isonic isn't a specialized speedboard or a funspeeder. I just want to have both fun and reach topspeeds with all my boards. I have used my GPS for several years now. I just want more speed with every board i have. I also have a F2 Missile (2006) and a Exocet TurboboostII 58 (2005). With these boards i've reached GPS-max speeds around 65 kmpu. The Missile once brought me to the 66,4 kmpu. (Strand Horst, 6 beaufort, 5.8 Neil Pryde RS6) Both the Missile and the TurboboostII are modern shapes. So i thought that an isonic also could give me these speeds. Till now my old Kinetic 58 gave me more topspeed.

The question is: How do i sail this Isonic 105 to these speeds? What do i need? Does this board need a different way of speeding it up downwind?

I've have learned to make a slow curve from halfwind to downwind. I have learned sail my board upwind between the gusts, en make a slow curve and throw it in the curves. The only thing that felt different in these downwind run's is that this Isonic doesnt speed-up like slalom or speedboards with a smaller tail.

My bigger light weather slalomboard a Kinetic K70 that also has a wide tail with big cutouts is also a bad downwind cruiser. I can steer it downwind, but it doesnt get much more speed than the narrow tail slalomboards or speedboards.

Has anyone discovered the same problem with the wide tail? Or is there anyone who can give me some good advise to purchase the right fin to reach the maximum speeds with this board.

21st June 2010, 02:37 AM

The F2 missile is more like an IS W49.
The Exocet TBII 58 is more like a IS W58.
Speed Specials, i.e.

I don't think you can put the IS105 into the same list of speed boards. It's just much more a slalom oriented board.

But nevertheless, I'm sure you can push the IS105 over 60 km/h.

I'll leave the fin choice up to the SB team. ;)

Marc 1964
22nd June 2010, 03:24 AM
No reply of anybody of the team exept a friendly man from Belgium.

No problem. There's a lot to read on the internet about starboard boards and their use. So today i purchased a nice Select SL7 33 cm.


mark h
22nd June 2010, 07:21 AM
Hi Marc
I think you just need more strong wind:) For sure, your iS105 will hit 65k (35 knots). 7m sail, 34cm fin and 25 knot winds and about 130 degrees down wind. I know that some have hit these speeds at Strand Horst on iS105/101 or similar.

Jurjen van der Noord even manage to peak at 38 knots on the bigger iS111. I have not gone faster than 34 knots on it with a 7.8m, but it will go faster:)


22nd June 2010, 09:16 AM
Mark, I used to have a Kinetic 2002 58 Ultralight Slalom. It is a VERY different board than the Isonic 105 and I am not surprised it goes faster in certain conditions. Just look at the dimensions of the Kinetic: 58 width and a 38 cm tail! It is a thick board (I was able to use it with a 8.0), but it goes fast easily, if quite out of control (I remember how hard it was to keep it planted at speed, talk about tail walking!).

Marc 1964
22nd June 2010, 02:14 PM
@ Mark h: I hope my new Select SL7 33 cm. fin will give me more chances to reach higher speeds in better winds. I saw some good results on the speedsurfing ranking website. I also think that the conditions must be a little bit better. For the last months we mostly had northwestern winds at Strand Horst and not the southwest winds that are better for downwind speeding. The weed must be full grown out there, and the water must be flat. And it shouldn't have to be so busy as it was last weekend. The weed drifted around and gave nasty spintouts in the area where normaly the most speeders sail.

@ Davide: The Kinetic 58 that i had for years was good to control for me. Maybe the volume suited me better because my weight is 83,5 kg. And the sails i used weren't so big. I used 6.3/6.6 and 7.4 on that board. The only thing that wasn't so nice about this board was the weakness of going upwind, ans the use in heavy chop. The wind often blew the nose away when the nose came too far up. At these points a modern slalomshape is much better. But for flatwater blasting and pure downwind speeding the Kinetic 58 was (till this moment) faster for me than the Isonic 105.

Erik Loots
22nd June 2010, 09:21 PM
Hi Marc,

I think the SL7 33cm is an excellent choise for the isonic 105, I had in 2006-2007 also this board and it was really a nice one. The select EVO 35cm might have been to big and draggy, not good for speedsurfing, might be a good fin for choppy slalomsurfing. The flat water of Horst allows a bit smaller fin, I think 33cm is good. I used for choppy surfing a tectonics goldwing 36cm at that time, for pure flat water topspeed tectonics falcon f1 30cm.

One other thing, I liked the footstraps all in the back. If you have a flying front foot it might work getting the rear strap 1 position forward. Masttrack is more personal, it changes from mid- to a few cm to the back.

And last but not least, make sure the sail has enough downhaul for topspeed. Especially with smaller fins.


Marc 1964
23rd June 2010, 02:41 AM
Thanks Erik,

I've being reading your blog. I saw some information about the Select SL7 fin's used as speedfins. Now i have all my fast fin's complete for my small slalom and speed boards.

For my ExocetII 58 i purchased a Caspar 31, and for my F2 Missile i have three fin's: Chocofin's Match one 28 cm, F2 original Missile fin 26 cm. and an older Select Viper speed 25 cm.

Enough stuff to get good results when the conditions are there on a day that i don't have to work.

Lets hope for some good winds for the coming weekends.

26th June 2010, 03:55 PM
For me being a tectonics addict, for speed on the 105/101 I use the tectonics falcon fins... they're also perfect for the smaller futuras. I use them in 28-30-32-34-36
For a slalomcourse the goldwing is ok, use it in 34-36-38

Marc 1964
27th June 2010, 03:33 AM
How are the Goldwings comparing to the Talons? Are the Goldwings a bit faster? Or just stiffer?

28th June 2010, 09:44 PM
Can't tell you, have no experience with the talon.

30th June 2010, 10:35 PM
Get yourself some Vector Maui Fins. I use these in my I Sonics and they are by far the best fins i used. I use the following fins on my boards :-

I Sonic W44/W49 - 24cm, 26cm, 28cm EX Speed (4.4m, 5.0m, 5.7m KA Koncepts)
I Sonic 86 - 30cm EX Speed & 32cm, 34cm, 36cm SL9 Alfa (5.7m, 6.4m, 7.3m KA Koncepts)
I Sonic 111 - 38cm, 40cm, 42cm Canefires (6.4m, 7.3m, 8.3m KA Koncepts)
I Sonic 144 - 46cm, 50cm Canefires (8.3m KA Koncept & 9.0m, 9.8m KA Race)

Hope this helps