Fin theory,tom,halycon and others

General Discussion
101

I have very little knowledge of how and why fins work but this thread is very interesting and informative. Bert, Halycon your fins are amazing. Thanks all for sharing the knowledge…

All this root cord talk has me wanting to pull all my cutaway fins back out. I have however noted that all the cutways that have been discussed and shown are used in a thruster setup. Is there any merrit for a cutaway type fin in a single fine application? I have the Stage 6 and that has a very norrow base but I dont recall ever seeing anyone surf a singlefin with a tradional cutaway. Would it lack drive?

Thanks

JL

102

Hey Longone,

In the skin friction thread that’s currently running I posted a photo of my 9’5" Junod with an 8.5" Whiteside centerfin in it that’s channeled. It’s a cutaway and is the template of choice for single fin longboards as far as I’m concerned. Plenty of drive, nice release from rail to rail, nice and loose when you’re going slow and if you need ot make quick turn to avoid and sitter or someone that’s in the wrong place in the line up when your at trim speed like I had to today all it takes is a little touch to change your line even on the 9’10" I was surfing today so I could avoid the nonsense in the line up. Sometimes there are just too many people not looking where they were going. So put up the little board a got out the old school performance longboard.

Mahalo, Rich

103

Not to open any cans 'o worms…but the topic is “fin theory” right? Here’s a Bobby Owens boomerang made for Keone Downing of Downing surfboards in honolulu. Removable, and Adjustable! Pretty small base on this guy.

104

I can’t tell from the picture, maybee its just a wierd angle, but would you call that a reverse rake fin? And all you fin guys what theiries do you have about how this fin would work. Possible problems and benifits?

105

yea halycon, the story is becoming clearer and clearer…

next thing , youll probably hear futures is up for sale right after the marketing campaign is over …thats probably why there current management isnt interested in developing my floating fins ,or wants to hear my foil critique…

coz there not planning on sticking around…and dont need any smart asses floating around with new ideas complicating things,so just bar the guy from using boxes and keep him quiet until its sale time…

hm another one of those cia conspiricy theories…

you dont have to take that comment seriously , its just my imagination working overtime…

hey rich could you please email me …

i lost your email address in my recent mishap…

ill sort that template with you as well …ill give you the original and my version of it ,see what you think…i already had contact with the template owners shaper and told him you were going to make a set based on that template , so he may end up contacting you before youve even made them…

im gonna run out to the car and grab some fins and snap them ,check out this package ,

the package in this pic is real fast with no effort …and joint snappingly sensitive , but lacks drive/accelaration on fat sections if you want to draw a line and work your fins for speed on nothing…but on the other hand with the smallest amount of push in the wave is extremly fast without having to work your board???

the only logical thing i can think of , is trailing vortex drag…

there would be hardly any(if none) coz you dont give the water a chance to move from the high pressure side to the low like you do with a more raked template…so you dont get water wrapping the leading edge kick starting the spiral…

i havent tried those fins in the magic carpet yet, maybe the tail area will make up for lack of drive over dead sections???

lokbox that fin you posted would be functional …

it agrees with the topic of this current thread about keeping the main body of the fin away from the turbulent boundry layer…

keeping it working more efficiently…

does it flex much???

judging on where the base sits in comparison the the main body of the fin it should feel fairly free , almost to loose and flappy in soft waves …could be camera angle but at first glance it may need to be set further back on the tail than your average fin to get the best out of it…on the other hand the extra area could offset the looser feel…

the vector foil thing is still coming its just a timing thing…time to write it …

ok till the next post …

regards

BERT

106

Bert, after speaking with Keone for more than an hour, I was very intrigued by the boomerang concept. We all know the sucess that bobby owens had with the design way back when, but Keone has applied it to many different wave conditions. Not just big perfect waves. The football shaped tip on the center fin slightly overlaps the trailing edge of the side fins. Keone stated that if you moved the center fin back at all, the board just shut off. The fin has suprisingly little side to side flex, but once mounted in the box, has a very neat tortional flex in the tip. He said as you loaded it up on a turn, you could feel it rotate into the water flow direction, and the board just turned tighter and tighter with no feeling of slip or loss of drive. He also had a very interesting take on single fins. He talked about that wave of brock littles where he free fell down the face at waimea, caught his flat side fin edge at the bottom,and got pitched off. He said he felt if brock was on a single, he may have made that wave! Stating that singles don’t “catch” in this manner. As the fin hooks up at the bottom, it would just pull the nose back straight, and under you, whereas when the tri hooks up, it wants to pull the board laterally, and out from under you. Like I said, hard to argue with this guy, and considering what he’s done, and the waves he rides…he had my undivided attention! Said he still rides singles exclusively at large waimea.

107

lok box i fully agree with those comments …we get our fair share of size down here…and in the past have felt very uncomfortable on a thruster in over 12 ’ especially 15…

when the side fin on a thruster bites it wants to pull the nose up and go into a bottom turn style manouver…

problem is when your not at the bottom its the last thing you want to do …

where as a single when it catches will allow the nose to swing down and make you shoot further out onto flat water , then you can decide when you want to turn…

i have rearanged my foils and fin configuaration to get them to still work at higher speeds with late drops…

im building one at the moment so i will post a pic of a good thruster set up for larger surf…in 4 or 5 days time…

so that fin is it a single or a tail thruster???

regards

BERT

108

From my understanding of theory, a forward sweep is inherently unstable and will try to rotate itself 180 degrees. Interesting concept for a fin. It would be interesting to see what kind of twisting forces it is putting on the base as compared to a similar fin that is swept back.

Maybe a compromise between the two.

109

Hey Bert,

My email address is

Those fins with the vertical leading edge are super fast but IMHO it’s the arc in the leading edge of a fin that gives its drive. My spinner template proves that to me every time I surf with it. I getting so I don’t want anything else as center fin in my boards over 7’6". If you just want to go fast (35 knots+) you’ll need waves with 45 foot faces on them and then a single like the rail fins with the vertical leading edge will work but only as a single. You’ll need to work the rails of the board to something that they will hold in those super steep walls cause if you just want to go fast then all you want is directional stability and as little drag as possible.

What I’m saying is that for waves under 10 feet, which is what we surf 95% of the time fins with a vertical leading edge don’t work well unless there is more going on than just a vertical fin. There may be a place for this sort of template but getting good surfers to test ride fins that are way out of the box is just about impossible. Maybe someday I’ll meet someone who will be will to work with me on some of my radical ideas to see how they work. I can only do so much by myself but I’m still ON IT! I have some plans for something way out of the box where this is concerned but I have to build the board for it. I’m looking forward to getting some fin boxes from Clyde at Edge Fins to try it in.

As far as the football fin idea is concerned. I think that if you want to maximize the radius of your turns that make a fin with the what I’ll call a reversed leading edge has merit. I rather doubt that this sort of fin configuration would be worth much in large waves at high speed. Because it would be too squirrely.

Here’s a little aside: Bat wings have a steeply reversed arc at the base of the fin. They fly at realitively slow speeds but are able to change directions in the breifest of moments. I once made a set of bat fins they turned out to be very jumpy. The idea was to be able to turn and 360 with ease. They never really got tested very well. There is still on floating around in one of my buddy’s fin quivers and I have one the rail fins tucked away. The other rail fin is at the bottom of the ocean because they are simply no good around kelp. I modified the template but haven’t made another set to this date. A photo of the originals are attached below.

When you boil it all down directional stability, lift and drive are the legs of the performance triangle that surround fin performance. As one leg changes in length all the others change as a result and thus the performance picture will be different. Close the triangle however you choose and remember – It’s all good.

Off to the fin shop, Rich

110

Lokbox… Agree 100% on Keone and his dad, world class

Anyway, there a local company called BC Rudders that sells fins at StrongCurrent on the northshore including a whole series of these football boomerangs under the artist labels, derrick doerner, mark foo and bobby owens. When I asked they said it was for their big waves guns…

I bought the Mark Foo version (the biggest) a month or so ago but am a bit afraid to give it a go cause it looks so wierd…

Question, is this fin only to be used as a single of as a thruster?

I’m thinking of pairing it up with a set of FCS CRV’s on a 9’0" high performance long board but not sure…

I tried a Greenough 8" paddlefin with the CRVs and they didin’t work. I’m thinking they need a small center so I have a 7" curtis cutaway and will be trying a BC rudders 6" cutaway similar to Halcyon’s swept back design.

I’m also thinking of putting this on my 7’11" ST McCoy single fin Nugget but the McCoy gullwing fin has kept me inpressed enough to leave things alone.

I also have that big red 9.5" Harbour boomerang flex fin I want to try but am not so sur eabout using a flex fin on such a wide tailed (18") board as the nugget.

Anyway grateful for anymore info you can provide on this design your showing…

Did you ask Keone about the Bong… My brother swore by one of those boards but I never got it…

Another thing I haven’t seen anymore is the long swept flex keel fin on a needle tail board. I had one of those in 72’ on an Iggy 7’0 beaknosed pipeline pin and it flew down the line something incredible… It was only like 4" tall with a base of 12-18 inches with a very long sloping rake.

111

bert, you have been in the industrie for years now, just go buy futures from someone else. you then will up thier buying price because of your combined volume… the gold coast has been doing it for years with fcs

112

If you care about lift, negative rake is well…a negative.

Traditional raked fins create lift from the resulting force vector on its high drag frontal area. On a traditional thruster, fin drag create more lift than any concave or bottom contour you can dream up…and yes they also create a more prominent rearward force component (drag)… I havent even covered the potential added turbulence that probably occurs at the the base of that fin.

Interesting looking fin but I would not expect it to do anything positive (other than tighter pivoting)…perhaps lots of double-takes on the beach?

113

Downing “Bong” fin:

114

115

I just came in from a surf in good waves with my FCS altered cutaways (like Meecrafty posted pick of). I can say they do pivot better BUT on my set I noticed significant increased drag, and I’d wager it is because I’m not a fin foiler and I should leave it to the experts. Halcyon- would you be interested in making me a set of mentals with cutaways for FCS? I’d love to try them (made from an expert).

116

Hey Tubedog,

Just for the record ~ Sure thing. I’ll look forward to an email from you at

Good Surfin’, Rich

117

If I werein Futures shoes, I would try to get as broad a patent as possible. Perhaps something like

“molded fin for box mount system with concave inner surface and convex outer surface”

They would try to claim no one had made a fin that was

  1. molded

  2. plastic

  3. for a finbox

  4. with a convex/concave foiling combination.

I’m not saying that is what they did. The approach of the patenter is to make an innovative product, then patent all the DIFFERENCES between it and that which preceded it.

As to your predicament, Bert, I’d recommand talking straightforward to your sales contact. Tell them you prefer Futures, and you prefer making your own fins. You like trying all kindsa stuff, and in no way are you trying to piss them off. Then, try to see exactly what they were in the pisser about.

118

its ok blakestah…i got information coming from everywhere at the moment…

with the amount of emails ive had in the last few days , i reckon i know what colour undies mike is wearing…

i still dont have the official ok to use the boxes, but at least i know whats going on…

different things are important to different people …

i cant really elaborate in an open forum…

question? how do you post a photo like the one above of aaron chang??

regards

BERT

119

Posting photos, I think you upload an attachment and choose to have it “inline” with the little box next to the attachment upload. I think it works well for pics that are not too large, it wreaks havoc if the pic is several hundred pixels wide.

120

ok might experiment…lets see what happens…

regards

BERT

836×444 62.4 KB