Fins...

General Discussion
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Quote:

Bottom line is glass-ons produce more lift (in terms of planing ‘‘lift’’), which is why they’re the choice of pros

trying to extract the maximum performance from a board in normal waves, and conversely, why tow-boards

work better with removables, where you don’t want the lift.

Wouldn’t there be more efficient ways to generate a little bit of extra lift?

I remember this came up some time ago, someone pointed out how the dorsal fin of sharks and dolphins where ‘attached’. And someone pointed out that this was not because of efficiency rather it was biological. Less ‘fillet’ would have less drag, but the ‘attachement’ would not be strong enough…

regards,

Håvard

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Quote:
Quote:

Bottom line is glass-ons produce more lift (in terms of planing ‘‘lift’’), which is why they’re the choice of pros

trying to extract the maximum performance from a board in normal waves, and conversely, why tow-boards

work better with removables, where you don’t want the lift.

Wouldn’t there be more efficient ways to generate a little bit of extra lift?

Once you’ve designed in all the lift you can get from the shape, getting more from the fin cluster seems logical/effecient.

Most of the other ways involve some design trade-off.

This is one of those 1% deals, only the very best surfers are going to notice the difference. For the rest of us, removables

are the way to go because of their ability to tune and change a board, as well as the travel convenience etc.

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no fillets: photos used without permission… Bruce Farr yachts…

http://www.farrdesign.com/pdfs/613design_info.pdf

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Glassing on fins is the lightest attachment method possible. Fillets are primarily structural reinforcment. Any extra lift derived from fillets is at the expense of drag. There are boundary layers of water as plane surfaces move through it. Immediately, adjacent to the surface of the plane surfaces the water is attached and carried along with the bottom tail of your board and its fins. As you measure further away from these planes the water slows until it is back at the rate it would have been if the surfaces had not been moving through it. Keeping this flow of water attached to the bottom of your board and the sides of your fins with the least amount of disturbance gives you the most control with the least amount of drag. The area at the base of the fins is the area where these to flows interact and cause turbulence. The larger you make that area of interaction, the more turbulence you create. This turbulence does create lift. But, it also creates drag and reduces control. So, at lower speeds this extra drag can feel beneficial. But, as velocities increase and AOA change this increased drag becomes worse and worse. So, you need bigger fins which also adds more drag. You can see a spiroling downward cycle as you try to get more speed and greater direction changes.

Another issue besides fillets that increase greater interaction between these two flows are loose fin systems. If your fin can move around at the base, you're creating more turbulence each time the base shifts from being loaded on one side to the other via the change in cant. That's why we've focused so heavily on making secure attachment systems.

The primary reasons most pro’s are riding glass ons are:

  1. The perception that an ounce or two of tail weight will make or break their ability to win the next heat. and, then they put a pound of traction on the tail.

  2. They don’t want to think about fin placement or fin design. They’d rather rely upon sorting through dozens of free boards their shapers give them until they find their magic board.

IMHO

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Hi Tom,

you raised some very good points,

I have been closely involved in pro surfing and noticed the trend you have mentioned.

i think the reason that pro’s also have resorted to glass-ons over the last few years is because of:

  1. fin systems were failing in general (due to poor installations and manufacturer’s cutting corners)

  2. poor fin system choices

  3. poor fin system quality, allowing the fins to “wobble”, so whilst allowing quick and easy fitting of fins actually created negative performance for the boards.

  4. overtightening of the grub crews (as the systems allowed) created an even bigger recess for the fin to “wobble” even more, increasing drift and turbulance.

This thread has been inetresting because it actually highlights how important adjustability is. All shapers around the worlkd know that replicating that “magic” board for their team-riders is almost impossible (but that is starting to improve now, given the better knowledge shapers have of the process that impact on performance).

As a shaper myself, i know there have been many times when the boards have come out perfect, and yet never felt as good as they were expected to go, until adjusting the fins transformed that good board into a magic one!

Don’t get me wrong, you can’t make a dud board magic, but by adjusting your fins, i know you can make a good board into that magic board to suit the surfer who’s surfing it!

adding rovings or fillets will increase drag, and has provided a more secure platform for the pros out there, however as Tom as referred to, the newer fin system technologies present today provide much more strength and versatility than glass-ons.

This is something the industry can learn to embrace, it can only benefit surfing, and it’s performance, and allow those boards to be used efficiently before being discarded, something right now we need to start looking at doing, so that we can minimize our impact on the environment etc etc…

Lastly, as noted by our lokbox competitors, guys like taylor who are now riding lokbox fin systems and Shaun “Gozzy” Gossman (top 10 wqs) who’s riding 4 ways, are both performing on newer tehnology fins sytems at present!

that is testament to those systems out there that are becoming far superior to the more well-know and established ones, and that’s something the industry can start learning from and start providing surfers with better product that’s out there…

Loved the thread, keep it going!

Regards

Deano

The World’s Leading Adjustable fin system!

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Will there be an 4WFS install video any time soon? Pictures speak several thousand words as they say.

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we do have an istallation video, be it a little outdated, but it essentially covers most points, however we are in the process of producing an updated version with comments from our pro riders etc…

Regards

Deano