myiW Current Conditions and Forecasts Community Forums Windsurfing Videos Buy and Sell Services
 
Hi guest · myAccount · Log in
 SearchSearch   ProfileProfile   Log in to check your private messagesLog in to check your private messages   RegisterRegister 
Another pow wow on the 'ol muti fin versus single
Goto page Previous  1, 2, 3, 4  Next
 
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Southwest USA, Hawaii, Mexico
View previous topic :: View next topic  
Author Message
westender



Joined: 02 Aug 2007
Posts: 612
Location: Portland / Gorge

PostPosted: Tue Feb 18, 2014 12:16 am    Post subject: Reply with quote

It's informative to hear opinions about things but it's like Mincemeat Pie. Someone will tell you it's the greatest thing ever but you might hate it.

I would try to get some test rides before I'd part with a load of cash.
Back to top
View user's profile Send private message
xander.arch



Joined: 23 Apr 2009
Posts: 172

PostPosted: Tue Feb 18, 2014 1:03 am    Post subject: Reply with quote

Totally agree that its best to try before ya buy. The nice thing about the new tri fin on shore / freestyle waves is that you can run then either as a single or tri. So you can change up the board pretty dramatically with fin configs alone. Yeah, the fins can get pricey, but I'd rather blow a couple Benjamins on fins than a couple Grovers on boards. And some of the new plastic fins are awesome and way cheaper than G10.
Back to top
View user's profile Send private message
U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Tue Feb 18, 2014 10:34 am    Post subject: Reply with quote

K4s are a composite fin, to call them plastic is like calling a Ferrari a transportation vehicle. (common enough to call them that )

Order from 4 Boards, and they remove the Value added Tax, they charge in UK or EURO countries, shipping amounts to about that deduction, so cost on their site is about what you pay. Never yet had any import tax/duty imposed.

They are a extremely reasonably way to test different lengths /foils and fin area.

I have a few. They have been making more models and with different density.

_________________
K4 fins
4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
Back to top
View user's profile Send private message
xander.arch



Joined: 23 Apr 2009
Posts: 172

PostPosted: Tue Feb 18, 2014 12:20 pm    Post subject: Reply with quote

Nice collection of 'plastic' fins U2. I've got a growing quiver of K4s as well - love em.

If you are in the SF or Santa Cruz area Joe Dihl at Davenport Surf Sail has some in stock. He can also order for you at a nice price. I'm about to place an order with him for some more ezzy assymetrics!
Back to top
View user's profile Send private message
scottwerden



Joined: 11 Jul 1999
Posts: 205

PostPosted: Wed Feb 19, 2014 11:33 pm    Post subject: Reply with quote

It makes zero sense (to me) for the thrusters to have toe-in, or toe-out. The primary purpose, and for BnJ, the only purpose, of fins is tracking - keeping the ass end of the board following the front end. Most of us point the nose where we want to go and expect the tail to follow.

Symmetric foils, which is what most fins are, only produce lift when the angle of attack != the angle of the chord of the fin. By definition, the angle of the chord for a symmetric fin is 0. Lift in this case is a force that tries to push the board back to a having the angle of attack == the angle of the chord of the fin. When the lift == 0 for a symmetric foil, the drag is at a minimum. This is the case of a single fin when we are just BAF'ing.

But when there is toe-in/out, the thruster fin is constantly in a situation of having non-zero angle of attack, even when you are going straight. Net result = drag. You slow down. Any lift produced by the fin is cancelled out by its mate on the other side of the board so what is the point of lift when you are more/less going straight?

Why would a manufacturer intentionally introduce drag into a tri-fin board? Or a quad fin? I can sort-of see how toe-in/out might benefit slashing on a wave but even that is suspect considering the extra drag you are always carrying around. Are we seeing marketing hype, or is the output of board/fin manufacturers have systematic design behind it?

Anyway, I think windsurfing could benefit tremendously by some real engineering. I tend to think a lot of what comes out of the shops is pretty ad hoc - try this, try that. See what feels right. Can you imagine what we would have if the engineers who work on America's Cup yachts turned their attention to windsurfing? (well, besides boards that cost 100k).
Back to top
View user's profile Send private message
westender



Joined: 02 Aug 2007
Posts: 612
Location: Portland / Gorge

PostPosted: Thu Feb 20, 2014 12:05 am    Post subject: Reply with quote

Is it art or science?

"How exactly does a posi-trac rear-end on a Plymouth work? It just does."
Back to top
View user's profile Send private message
xander.arch



Joined: 23 Apr 2009
Posts: 172

PostPosted: Thu Feb 20, 2014 12:28 am    Post subject: Reply with quote

For bump and jump I sail my tri fin as a single. I also can't see a logic to use asymmetrical foils and/or toe-in for multi fins in B&J conditions. But for waves, its a different story. The toe in and asymmetric shapes are borrowed from surfing where they are the proven norm.

I've got nothing scientific to ad, and I'm probably not a good enough wave sailor to really discern what is going on, but I am willing to try things out (especially at the cost of a few plastic fins). If it works for me, I'll stick with it. What I have noticed is that the K4 Ezzys kind of hook you into a tight fast bottom turn. I've also noticed that since switching to ezzy's, I carry more speed out of the bottom and in to the top turn. This of course is good and has improved the flow of my wavesailing a lot - at least I think that is the case. Others have said that they noticed a change for the better as well so I'm gonna stick with em for the time being. The ezzys are a little squirrely in a straight line so I'd never think of sailing them in anything but waves.

But, to be honest, the biggest detriment to the ezzys is that they add two new variables to the multi fin equation which can feel like overload. I've KIND of figured out multifins for myself, but it definitely takes some trial and error to find a setup that works for you and your local spot.
Back to top
View user's profile Send private message
isobars



Joined: 12 Dec 1999
Posts: 13844

PostPosted: Thu Feb 20, 2014 8:43 am    Post subject: Reply with quote

Boards crab even in a beam reach, and most multifins are optimized for sailing up on one rail in a turn. Thus the toe. But their superior tracking precision in very rough water, where control is king, still lets them be very fast if the hull is not too rockered out. My 5-finners had a flat rocker for speed, yet cranked turns like very few other boards in really gnarly conditions, according to scores of thousands of my own miles on them and to WSMag east coast testing. Their toe angle was proprietary and based on years of testing.
Back to top
View user's profile Send private message
U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Thu Feb 20, 2014 9:15 am    Post subject: Reply with quote

scottwerden wrote:
It makes zero sense (to me) for the thrusters to have toe-in, or toe-out. The primary purpose, and for BnJ, the only purpose, of fins is tracking - keeping the ass end of the board following the front end. Most of us point the nose where we want to go and expect the tail to follow.

.


I will come back to this(or not) : right now I dont have time to develop a proper response. It seems that no amount of discussion would change you mind anyway. Measured by K4 for toe in include some models from
household names, RRD, Fanatic JP Tabou Naish Goya Simmer THAT have toe in. Some are thruster tri. fins and some are quads.


What I have found if you use toe in ( no one I am aware uses toe out)
with symmetrical fins not more than 1.5 degrees, if you use asymmetrical fins, which are a standard foil OUTSIDE towards the rail , and any variation inside from flat, to S curves to numerous variations, then they work best with more than 1.5 degree of toe in, so 2--and up, my conversions have around 2.

My friend uses both more toe in and shaped fins that have toe and curve. I am a lowly garage builder , he OTOH is a NASA scientist/engineer, I am using that NOT NOT as a line... , that IS what he does.

SURF Boards have and do used toe , front and rear, quad thruster 2+1
and everything in between, just one

difference between windsurf and surf boards is the amount of sideways force that is exerted on the board and fins to counteract the pressure from the sail, particularly when sailing upwind.

there are some many things that affect the performance of the board, other than where the fin cluster is placed, and toe in. rails rocket bottom shape, and of course YOU.

_________________
K4 fins
4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
Back to top
View user's profile Send private message
U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Thu Feb 20, 2014 10:26 am    Post subject: Reply with quote

the Ezzys referred to are K4s with built in toe, 1 2 or 3 in some bases< Graham Ezzys signature model .
references to straight line sailing, a single fin in most cases will TRACK better, not turn nor go upwind better.

If you haven't sailed the fin variations as a direct comparison on the same board , you have an opinion or glorify it more a theory..
The fact that production boards are now having toe in, indicates that its not hype... YMMV

I like the reference to the posi traction, and cars in comparison to windsurf concepts in general, you could have a 500BPH engine in a Chevy Chevette
with 165/13 tires and it will go blindly fast in a straight line, but a box stock Mini Cooper will pass it in the turns

_________________
K4 fins
4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    iWindsurf Community Forum Index -> Southwest USA, Hawaii, Mexico All times are GMT - 5 Hours
Goto page Previous  1, 2, 3, 4  Next
Page 2 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum

myiW | Weather | Community | Membership | Support | Log in
like us on facebook
© Copyright 1999-2007 WeatherFlow, Inc Contact Us Ad Marketplace

Powered by phpBB © 2001, 2005 phpBB Group