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isobars



Joined: 12 Dec 1999
Posts: 20935

PostPosted: Tue Feb 07, 2012 4:03 pm    Post subject: Reply with quote

Material matters, but shape (aka planform, outline, type) is even more important. Every shape and material has pros and cons, and an attentive intermediate to advanced sailor, even one who can't yet plane through many gybes, can feel differences between softer and stiffer fins, wave vs B&J vs racier fins, short vs medium vs long, low vs high area, short vs wide/long chord length, thick vs thin, slots vs no slot, foiled well vs poorly, loose vs tight in the box, chipped vs intact, maybe even fresh vs weakening structurally, etc.
• Stiffer, straighter, longer, larger, and/or thicker fins (plus board, skill, and rig factors) favors upwind drive.
• Flexy fin = springy jibes (i.e., you can actually feel the fin's twist storing energy during the carve and releasing it when you back off on the rail pressure.
• Your fin preferences will change if and when you start carving rights and lefts on your way across the lake, or start doing tricks, or want to go more upwind or downwind, or faster, or higher ...

It's so complex that, as UT**3 (UT cubed) said, ask the fin professionals for now. You can experiment on your own as your knowledge, skills, demands, and fin access improve.

Mike \m/
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sailingjoe



Joined: 06 Aug 2008
Posts: 1087

PostPosted: Tue Feb 07, 2012 5:57 pm    Post subject: Reply with quote

Let's see, if shape boils down to planform, outline, type where does foil fit in? Fins offer the windsurfer a technical side to their sport. If you are attracted to that, you won't really use your knowledge unless you put in an exceptional and serious amount of T.O.W. I have a wide selection of fins with which to sail, but not only do I not need it, I really put myself in the middle of a vast majority of sailors deemed recreational sportsmen and must say that the subtle nuances of my fins are lost upon me.
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Tue Feb 07, 2012 6:34 pm    Post subject: Reply with quote

lets see FOIL, OK
on almost all windsurfing boards the fins the foils are 50/50 dual or the same on both sides and convex.

The more prominent company that sells boards and fins with other than 50/50 that is Witchcraft from the Canary Islands, off the NW Coast of Africa.

They make a 2+1 , the side bites are the asymmetrical fins , the centers are always dual foiled or 50/50

fins , no matter what foil they have if other than 50/50 are called asymmetrical, so one side is different than the other, VS symmetrical which means they are the same on both sides. If you can't remember which way that is think ASS, is a bit odd therefore asSSymmetrical .

There are many variations of asymmetrical fins, flat inside , flattish inside, 70/30 & 80/20.

The large surf board fin companies make many variations:

see here:

http://www.surffcs.com/us/technology/fins/Foils.aspx

with toe in , which is the fins pointing towards the nose, rather than parallel to the center line, offer better upwind, tighter turning and variations of feel, loose or firm.

these fins are all asymmetrical, and quite different in materials and inside foil tech


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



Joined: 26 Jan 2007
Posts: 481

PostPosted: Tue Feb 07, 2012 8:11 pm    Post subject: Reply with quote

isobars wrote:
Material matters, but shape (aka planform, outline, type) is even more important. Every shape and material has pros and cons, and an attentive intermediate to advanced sailor, even one who can't yet plane through many gybes, can feel differences between softer and stiffer fins, wave vs B&J vs racier fins, short vs medium vs long, low vs high area, short vs wide/long chord length, thick vs thin, slots vs no slot, foiled well vs poorly, loose vs tight in the box, chipped vs intact, maybe even fresh vs weakening structurally, etc.
Mike \m/

good write up Mike Laughing Laughing

http://www.select-hydrofoils.com/en/news-more/the-fin-what-you-need-to-know/

check the info here pretty good knowledge base to learn about fins material and profile as well flex and twist etc.

aloha
Jurg
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Sailboarder



Joined: 10 Apr 2011
Posts: 656

PostPosted: Wed Feb 08, 2012 6:57 am    Post subject: Reply with quote

I would like to point out that there are assymetrical single fins available too.

http://www.cameraid.com/lessacher/tech.html
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keycocker



Joined: 10 Jul 2005
Posts: 3598

PostPosted: Wed Feb 08, 2012 8:38 am    Post subject: Reply with quote

G10 is an electrical spec for enclosures that refs only to density.It can be stiff,flexy,crumbly,whatever as long as it has a certain density.
It's use to refer to stiff fins is just surfer talk like "glass boards" means polyester resin construction in the gorge,though nearly all boards are made with some or all glass fibre.
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Wed Feb 08, 2012 9:40 am    Post subject: Reply with quote

Sailboarder wrote:
I would like to point out that there are assymetrical single fins available too.

http://www.cameraid.com/lessacher/tech.html


the actual reference was to a 2+ 1 fin setup a tri fin center

I recall seeing this before, sorry I overlooked it, and should have said center fins for the 99% are symmetrical. I haven't a clue in what conditions this is favored to perform

Lessacher fins from the one I saw is very precise and well made, also quite costly.

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

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


Last edited by U2U2U2 on Wed Feb 08, 2012 10:12 am; edited 1 time in total
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Wed Feb 08, 2012 9:43 am    Post subject: Reply with quote

keycocker wrote:
G10 is an electrical spec for enclosures that refs only to density.It can be stiff,flexy,crumbly,whatever as long as it has a certain density.
It's use to refer to stiff fins is just surfer talk like "glass boards" means polyester resin construction in the gorge,though nearly all boards are made with some or all glass fibre.


well , crumbly would not be a characteristic that any G10 fin that I have ever seen, until its damaged.

I think it more a process of the components to achieve the stiffness, from memory was used first in circuit boards.

a Wikipedia search from one of the companies say :
Lamitex® composite materials are engineering materials made from fibrous reinforcement such as cotton cloth, paper or woven fiberglass cloth, which are bonded together with high quality plastic resins. The layers are pressed together under high-pressure and the resin is baked until it becomes solid, fusing the material into a tough, strong composite. Combining different resins, - such as phenolic, epoxy, melamine or silicone - with different types of reinforcement creates a full range of Lamitex® grades to suit a wide variety of applications. Lamitex® high-pressure laminates combine mechanical strength and electrical insulation with chemical and weather resistance. They're rigid with high strength - to - weight ratio and can be machined to very close tolerances required on finished components.

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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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3-phase



Joined: 26 Jan 2007
Posts: 481

PostPosted: Wed Feb 08, 2012 1:12 pm    Post subject: Reply with quote

keycocker wrote:
G10 is an electrical spec for enclosures that refs only to density.It can be stiff,flexy,crumbly,whatever as long as it has a certain density.
It's use to refer to stiff fins is just surfer talk like "glass boards" means polyester resin construction in the gorge,though nearly all boards are made with some or all glass fibre.


Agree our friends from overseas say its G10 but it can be from crappy to very good stuff as they have a wide spread in there supply chain. And if they are machined and then hand sanded means they are not equal from fin to fin.

Question to all. I had several pros say after 30 to 50 days throw a G10 fin away, do the material is loosing its initial flex /stiffness from flexing what do you think or what is your input on that?

Aloha
Jurg
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U2U2U2



Joined: 06 Jul 2001
Posts: 5467
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Wed Feb 08, 2012 1:27 pm    Post subject: Reply with quote

I think G10 is stiff enough to not have a memory.

But have heard from a pro as well, that they curve with the same flow

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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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