Fin Evolution

[Lehmann108]

I've got a question regarding freediving fins. I'm an old goat of 52 and when I started snorkeling at 9 the only fins I had were short, rock-hard, paddles. Twenty years later the fins had evolved to hard, black rubber, US divers toe-busters. Basically they were just larger paddles. I've come back to snorkeling and freediving recently (I didn't know I was freediving as a kid!) and am amazed at the evolution of fins. They are much more efficient now. What I can't figure out is why the freediving fins have not taken advantage of this engineering advantage. Freediving fins are flat, flexible paddles. Why no split-fin; why no scoop-effect?

 

[trux]

Yes, I have very similar experience, and same opinion. I asked similar question, or expressed hopes for more efficient freediving fins in several threads (i.e. [thread=64238]here[/thread], [thread=65475]here[/thread], or [thread=65311]here[/thread]).

On my mind, there are two main reasons:

1. The market for freediving fins is way too small. Big part of it is covered by very small manufactures who do not have sufficient means for development and extensive testing that is definitely needed if you want to create a hi-tech fin. For the bigger manufacturers, the freediving products are far less important, so investing into the development there is also not a priority
   .
2. Freedivers and especially competitors are very conservative. Persuading a freediver to use a new type of fin that requires completely different style of kick is a challenging task.

As you can see from the other threads - many freedivers are extremely sceptical or even right-out hate splitfins.

For this reasons it will certainly take little bit more time before we start seeing more advanced and more efficient freediving fins, but unlike some others I share your opinion and do not think the current design is the optimal and final solution.

 

[Walrus]

The regular split fins are ok for shallow depths but aren't very good for normal freediving. The main reason is the scuba split fins are way too small, and would require a very high kick cycle, like a very low gear on a bike. Also for deeper depths you need to overcome negative buoyancy and long fins grab more water and you can put more power with a slower kick with them. What is efficient for a scuba diver doesn't mean it works for a freediver. Some of the bigger scuba fins can be quite ok for freediving. My favourite fin for recreational freediving is the mares quattro power - works really well with a dolphin kick, also easier surface swimming then long blade freediving fins.

If you look at carbon fibre or fibre glass freediving fins they are really efficient, you can't really compare them to plastic fins. Perhaps if you had very large split fins they may work better for freediving. Having said that, if you look at the majority of the top competition freedivers are now using monofins. They are the fastest fin you could get, and you can utilise more muscle groups then just your legs. If someone with split fins were to enter in a monofin race they would be left behind a long way. If you talk pure 'efficiency' as in power in power out it is more complicated then that for freediving. You actually want to use Anaerobic stores in the muscles during the dive, and this doesn't cost you your lung O2 stores so this is 'free' power, well sort of.

P.S. I have done heaps of scuba diving and freediving, and I have owned and tried all types of fins, split fins, 'scoop' fins, carbon freediving fins, monofins etc

Cheers,
Wal

 

[kmo]

I started out freediving with short bodyboarding fins, then bought some split fins when I did my scuba ticket, then moved onto some long freediving fins about 2 weeks ago as I've started to get into deeper water.

I found the split fins were a huge step up from the bodyboarding fins, and other scuba fins I'd used, and certainly helped me to progress to the next stage of freediving. I'll keep using them for scuba too, as they are very comfortable, are good for manouevrability and if you are in no hurry are good for conserving air.

I'd done most of my free diving alone or with other novices until recently, and some very experienced people I went out with noticed that I was having to kick very fast to get to the surface in my split fins.

Having now tried the long fins a couple of times, I can definitely appreciate the difference in the top speed you can reach and the number of "revs" you have to do to get there.

I'm certainly not gonna say that there aren't going to be more efficient ways to kick around than what we are using though, fish still seem to be moving a lot faster than me I haven't tried a monofin myself, they aren't too common amongst spearfishermen.

I think that from a hydrodynamic point of view, most of the channels and ridges in fins would do very little (if anything) to help, and would probably increase wetted surface area, and cause form drag as the water was moved around corners. I think that they offer more in a structural sense, and freediving fins have moved towards more rigid materials rather than shapes to achieve this strength without drag.

Thats my two cents, I'm pretty new to taking freediving seriously but I'm a naval architect by trade and have been using fins bodyboarding for the last 15years.

 

[AlexF]

I have been diving for a long time and have 2 brothers and several cousins that have been diving with me for close to 30 years, so I have been able to test a lot of fins (we usually like different stuff).

Most of my diving was with scuba, so at the beggining, my equipment was focused at scuba. Freediving was done in between scuba dives.

A little over 20 years ago I tried the Scubapro JetFin fins and they were great fins, compared to my old ones, and used them for a long time until they got lost in a ship wreackage. Then I started testing different fins, that was a little over 10 years ago. I tried almost every brand, from Tusa, Mares, Scubapro and so on. My younger brother got a pair of split fins and at the end I ended up purchasing Scuba Pro Gorilla fins.

Comparing the Gorillas to the split fins, the first ones were much stiffer and swimming in the surface was a little harder, the split fins were a joke. They are so soft they don't take you anywhere. As other posts say, they conserve air, but that is because there is very little resistance to the water.

About a year ago I decided to start freediving (spearing) in blue water and M. Labbocetta convinced me that the freediving fins (Omer Bat) were great fins and that there was no comparison with the scuba fins. I was a bit skeptical and couldn't understand the price difference of the top of the line ScubaPro ($180.00) to the Omers (close to $300.00), but went on and purchased them.

My first trip was with my brothers and I did several tests to compare both fins, and as Mark told me, they are two different animals, and you get what you pay for.

On a single breath, swimming at 15 to 20 feet deep I would get 50 to 60 feet ahead of my brother using regular scuba fins, and using scuba tanks, all of the split fin divers could just not catch up with me, even though I was swimming at normal pace. At the end of the dive I had over 1,000psi over what the rest of the other divers had. While on scuba, the fins don't play a big role, if you have bad fins you might consume more air and you might not get to see the whole reef, but it's no big deal.

Now freediving fins are extremely important and if you don't have to kick as strong to get moving, so you can spare more oxygen and get deeper or stay longer, which is a BIG thing.

I haven't tried the carbon blades yet, but will be getting them next friday, but I'm told they are much better than the fiberglass.

 

[cdavis]

Lehmann,
Longfins approach efficiency differently from split fins or short fins, in a way that is more suitable for freediving. The longfin concept represents as much a breakthrough design as split fins. Watch a diver using short fins, scoops or not, think about where the fin is pushing water. Much of it is going either up or down, not back, and not contributing to propulsion. Watch a longfin user, particularly one using soft blades with rails. There is a lot of bend to the blade and as it straightens out, a far larger percentage of water is being moved back, ie, a greater percentage of the divers effort is translated into propulsion. Split fins do it a different way, but, so far, nobody has designed a split fin that suits freediving. It may or may not be possible.

Connor

 

[hteas]

Another way to look at the differrence in fins is in what you want out of them. Freediving fins serve two very good purposes
They allow you to kick more slowly. This is good if you are spearfishing
The allow you to put a lot more power into them when its time to head up
Smaller fins work like a road bicycle. Faster cycle rate to conserve energy in aerobic conditions. The German Navy Seal that holds the SCUBA distance record used Force Fins. They are easy on your legs and are efficient in terms of O2 consumption. But when you are a long way down that is not what you want!!
As for the other designs: Jacque Mayol (in Big Blue) at one point was using blades with vents to aleviate the vacuum that forms on the back side of a blade as it moves through the water, and Enzo used vented blades when he went into the wrecked ship (no, I don't pretend that either knew what he was doing, but rather that the technology has been tried). Walrus experimented with splitting the blades on his freediving fins a couple of years ago and decided it wasn't worth it. So, they have been tried, and didn't catch on.
Fiberglass and carbon fiber blades are technological improvements that really does seem to work. I definitely like my SpecialFins glass blades, and a lot of others don't seem eager to back to plastic either. I went with medium stiffness and stiff foot pockets (Picasso) since I do a lot of surface swimming. Along with the blades, I use a modified kick on the surface. Its more of a push kick that pushes the water back. You start with a bent knee and push straight back. It gets rid of the standard problem with any big fins. Instead of lifting your butt up by pushing down, you are pushing yourself foreward through the water. Big improvement.
FYI I started snorkeling in '53 and have gone through a lot of equipment and fads. Using Duckfeet UDTs and Aqualung Professionals was responsible for my trashed ankles. Too heavy, too long, and too stiff. The new stuff really is worth it.
Howard

 

[Haydn]

OK, so what are the fastest bi fins suitable for long distance surface finning (longer than 10 hours)?

 

[hteas]

If you have the testosterone to keep going for 10 hours, I'd go with SpecialFins in soft or medium hardness (assuming you can afford them).
Other choices are Matrix fins and LeaderFins. Go soft to medium for looooong days. I've been to 39 m with my medium fins and had no trouble getting back up. The longest I've used them continuously is 8 hr, with only minimal cramping.
The best are soft C-4 carbon fins (pricy and fragile)
In a plastic fins, Sporasub Dessault HD, Picasso Start, or Omer Winter or Bat 25. After that its personal preference.
The stiff blades many freedivers like so much will kill you on a long swim.
My personal preferences
Howard

 

[marginatus]

About the c4 fins... their pricy, no argue. But fragile?! i don't own any c4 fins but i'm thinking of buying ones and my question is: Who has broken c4 fins? And in what conditions that happened? I ear a lot about carbon fiber fins beeing fragile and i eard of some broken fins but any c4??

thanks for the help

 

[Bill]

I haven't been able to find anyone else that broke a C4. In my case, the side rails on the foot pocket came loose and when I made a clumsy turn the first kick broke the -40 blade at the bend. I saw a video of a dealer who hammered a C4 blade on a tow hitch without any damage. For me they are no more fragile than plastic blades.
Aloha
Bill
P.S. Maybe if I put the single blade on e-bay we could find out if anyone else broke one.

 

[Jon]

I've never brokenn a C4 blade, but I have broken a Sporasub Pure Carbon blade- twice!

I wouldn't be worried about the C4's, they are stronger than you think and OMER has a great warranty on them.

Jon

 

[AlexF]

The only problem I've had with the Falcon C4 is that they become loose from the foot pockets, and they tell me that is what breaks the fins. I tried using silicone, but it did not stick to the rubber.

I'm going to try using a different kind and more glue next time.

 

[Jon]

I used 3M 2500 Marine Selant on one pair and Aquaseal on another pair.

Jon

 

[cdavis]

Haydn,

10 hours eh, what in the world are you planning? I'll assume this is serious and throw out some ideas. I do a 1200 yard set, kick only with longfins, during my pool workouts, plus several middle distance sets free style with short (body surfing) fins Based on that and a fair amount of experimentation, the following thoughts.

I haven't found a freestyle form that works well with longfins. This might be a problem for you when combining arm and leg strokes.

For kick only, longfins are much more efficient than short or scuba fins. Haven't tried split fins.

Using longfins for extreme distance on the surface, get the softest blade you can find, preferably one with an angle. On soft blades, an angle is less important than on hard blades, but still makes a differance on the surface. Full side rails are best. I haven't tried carbons, they are probably better than what I use. For me, in this application, Waterway #2 are better than Specialfin Hybrids (hard).

Kick style for extreme distance is going to be very different from short distance. Finding the right combination will probably take some considerable experimentation. Kick style can greatly affect your choice of blades. I suspect that, once you perfect your stroke, having a set of blades custom made, just for this swim, would be a real plus. Just a guess, but extremely soft and slightly shorter than regular longfins might be the ticket.

Good luck with your project and the arrythmia.

Connor