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Wave fins - how to they differ between singles and multi

 
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manuel



Joined: 08 Oct 2007
Posts: 137

PostPosted: Fri Jun 20, 2014 12:27 am    Post subject: Wave fins - how to they differ between singles and multi Reply with quote

Can the center fin of a tri fin be used as a single? Can one of the rear two twin fins used as a single?

I tried an MFC tf200 as a single but didn't get the extra softness I was looking for. It still felt hard to break loose at the top turn.

Shouldn't multi fins have more flex than singles?
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U2U2U2



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

PostPosted: Fri Jun 20, 2014 9:38 am    Post subject: Re: Wave fins - how to they differ between singles and multi Reply with quote

manuel wrote:
Can the center fin of a tri fin be used as a single? Can one of the rear two twin fins used as a single?

I tried an MFC tf200 as a single but didn't get the extra softness I was looking for. It still felt hard to break loose at the top turn.

Shouldn't multi fins have more flex than singles?


1. YES, it will need to be longer, rx if the center in tri fin setup is 17cm, a length of 23cm will need to be used to increase the fin area, numbers are examples.

2.umm...why ? Only if you have some ultra special need to have the right or left fin only in unbalanced condtion, maybe a break that has right or left breaks, but even then......umm

3. All fins are not the same ... the MFC was probably G10..stiff..other consideration are available, also thats the nature of the single VS tri or twin, bigger fin, more depth in the water.

4. Fin feeling is going to depend on size, both length and area and the material used, G10 or composition or whatever the particular company calls its non G10 versions. Being flex y or firmly planted is a characteristic that the sailor need to determine, smaller sides will loosen up the feel. G10 center // flex y sides rx.

K4 is a pioneer in several areas, price, they are very reasonable , they offer super flex fins, and one that are close to G10 in feel.

K4 are a United Kingdom firm, sold thru dealers. 4 Boards have the web site set up to order without the VAT, EURO community taxes, the original price quoted is about the cost including shipping.

The K4 center fin may pose a problem in length, but additions all the time,they also have a freestyle fin that could be used. FWIW these are plastic, but very sophisticated plastic.

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4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
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spennie



Joined: 13 Oct 1995
Posts: 823
Location: Thousand Oaks, CA

PostPosted: Fri Jun 20, 2014 10:59 am    Post subject: Reply with quote

As long as we're talking about fin flex, has anyone ever heard of a flex-fin for windsurfing? I realize that all fins flex a bit, but in my 24 years as a sailor it's always been trying to find the stiffest material - hence, G-10. Did anyone ever make a purposely flexy fin? Did it work, or was spinout too much of a problem? Seems like a single flex-fin would work in waves, if not slalom. We used to make our own surfboard fins in the early 70's, and sometimes we'd make them really thin so they'd flex, seemed to work really well surfing, would kind of "boing" you out of a turn.

Hmmm. Maybe I'll take a power sander to one of my old fins.....

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cgoudie1



Joined: 10 Apr 2006
Posts: 1250
Location: Killer Sturgeon Cove

PostPosted: Fri Jun 20, 2014 11:07 am    Post subject: Reply with quote

I have a "Wardog Extreme Wave" 8.5 inch fin that is billed as
flexy, and I love it! Not sure what the material is, but the tip does
bend off quite a bit, so probably not G-10. I also have a Curtis
9 inch that is G-10. Also an excellent fin (you can really get on
the thing without spinning it out), but not nearly as "surfy".

-Craig

spennie wrote:
As long as we're talking about fin flex, has anyone ever heard of a flex-fin for windsurfing? I realize that all fins flex a bit, but in my 24 years as a sailor it's always been trying to find the stiffest material - hence, G-10. Did anyone ever make a purposely flexy fin? Did it work, or was spinout too much of a problem? Seems like a single flex-fin would work in waves, if not slalom. We used to make our own surfboard fins in the early 70's, and sometimes we'd make them really thin so they'd flex, seemed to work really well surfing, would kind of "boing" you out of a turn.

Hmmm. Maybe I'll take a power sander to one of my old fins.....
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manuel



Joined: 08 Oct 2007
Posts: 137

PostPosted: Sat Jun 21, 2014 11:35 am    Post subject: Reply with quote

I'm sorry I wasn't very clear.
I'm referring specifically to shapes and flex not size per se.
Can any of the "multi-fin" fins be used on a "single-fin" board?

This is MFC new high flex design: http://www.mauifin.com/windsurf/pro-flex/single-wave/ Looks super sweet. But the thing is 20cm is still too much fin for me (sailing a 77 freewave with a 5.0) OR maybe thanks to the new flex, it feels smaller?

Anyway, the multi-fins are available in much smaller sizes but have a different design. Below blue is single, red is multi.



Multis appear to be more raked back and wider uptop.
They seem to have more surface overall.

I use the stock natural wave 24cm on an 86L wave board, it's quite soft and spins out easily, I have tried three fins on my fw77 the stock rigid fw 23cm, a fw20cm quite rigid too and the center fin 20cm of a tri-fin (the red one above). The multi-fin fin had a little bit smoother flow than the fw 20cm but not much difference overall.
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isobars



Joined: 12 Dec 1999
Posts: 14157

PostPosted: Sat Jun 21, 2014 12:34 pm    Post subject: Reply with quote

spennie wrote:
[b] has anyone ever heard of a flex-fin for windsurfing? ...Did anyone ever make a purposely flexy fin? Did it work, or was spinout too much of a problem? ... would kind of "boing" you out of a turn.

Sure ... and I agree with the "boing" sensation. I am far from being a fin techie, as I just swap 'em out until I find one I like with a given board, but I have, and have and have seen many more, fins with huge amounts of flex and/or twist. I just picked up one and twisted/flexed its tip by over 30 degrees by hand, and Real Wind used to use a vinyl fin whose edges would all but roll up around its stiff core if pushed hard. That fin was very thin, felt drag-free even in a wave shape, and worked beautifully.

I'm sure technology has left the following brute force idea in the dust, but a budding pro freestyler told me many years ago that his buds were going to undersized rigid G-10 fins, rather than flex, to achieve breakaway.* After all, isn't the primary purpose of intentional flex/twist to alter the angle of attack under excessive loads in order to prolong laminar flow and thus delay breakaway (aka spinout, aka turbulent flow)? Doesn't the same idea justify sail leech twist?

* I, fer one, can't keep undersized single fins under me. On boards that come with little postage stamp 18-22 cm wave fins, I immediately switch to 24-26 cm fins so I can push them HARD when I want to go upwind in rough water and land jumps pointed upwind in the process. Bigger fins greatly expand my lateral freedom on the water to go way upwind, bomb far downwind, and repeat as desired, sometimes within one reach across the river. Fer two, magazine board tests agree; they very often say that a given wave board needs a bigger fin to get upwind, or that the board has limited upwind ability (or is slow). I very often say. "THEN PUT A BIGGER FIN AND A BIGGER SAIL ON THE DANG THING AND OPEN 'ER UP". I'd rather open up the board's speed and lateral access than slide sideways; folks who like spinning out (e.g., for tricks and slides) can pursue other choices.

Isn't choice great?
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U2U2U2



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

PostPosted: Sat Jun 21, 2014 12:52 pm    Post subject: Reply with quote

manuel

sure multi fins can be used on a single.

The smallest FIN I have ever had for a single fin board was a 19cm

the largest multi fin that I KNOW, ( without look at all the fin companies sites is a 17cm) the area of a 17 could reach pr equal a 19cm fin, could.

your lastest post has me confused what you what or are trying to do.

There is no reason why you cant use a pair of single fins, like rx in a HiFly Twin, doing the opposite would be limited only by the size. Of course the overall shape, would have to be acceptable.

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4Boards....May the fours be with you

http://www.k4fins.com/fins.html
http://4boards.co.uk/
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manuel



Joined: 08 Oct 2007
Posts: 137

PostPosted: Sat Jun 21, 2014 9:13 pm    Post subject: Reply with quote

I'm trying to understand shape differences between multi-fin and single-fin designs.

If we can interchange them then why would the shapes differ?
Also, which one has more flex?

My understanding is that a design with more flex allows us to get away with more length (useful to go upwind on side-on conditions) but feature the looseness of a smaller fin (useful down the line.)
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U2U2U2



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

PostPosted: Sat Jun 21, 2014 10:01 pm    Post subject: Reply with quote

[quote="manuel"]I'm trying to understand shape differences between multi-fin and single-fin designs.

If we can interchange them then why would the shapes differ?
Also, which one has more flex?

My understanding is that a design with more flex allows us to get away with more length (useful to go upwind on side-on conditions) but feature the looseness of a smaller fin (useful down the line.)[/quote

Shape is going to be dictated by the designer. Multi fins have many different shapes including weed.

The shapes on single fins from MFC MUF BPF K4 Choco TFC True Ames Mankani are not going to be the same, similar. Stands to reason without going into Fluid dynamics, which I dont feel qualified to irregardless, that multi fins in the same length will have different shapes, areas.

If the fins are G10, and their exist several stiffness of G10, the fins will be stiff compared to most if not all other compositions.

Flex in itself is only one characteristic of the fin ,I would NOT consider a flexy fin to be used longer, instead look at one that was the same length, but more area, to achive upwind et all.

K4 say on the Flexy version

Our original fin for performance wave riding. Lots of flex for amazing grip and looseness on the wave. Raked template for control. A progressive foil for different flows between tip and base. Test winner. Will loosen up a 'stiff' board and are particularly sweet as twin fins as they eliminate that unwanted top turn spin out.

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http://www.k4fins.com/fins.html
http://4boards.co.uk/
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