Kicking

Once, when looking through a dive company’s catalog, I noticed the descriptions of the many fins they had for sale. One description said “triple vented for maximum power.” Another fin was described as “unvented for greatest force”, or something close to that. How can a fin with vents be maximum and one without be greatest? I decided to see what other catalogs said.

One fin claimed best optimization while in the same catalog a different fin was fully optimized for best results. Another manufacturer said that a particular fin was the world’s most popular (not quite sure how one establishes that). Yet another fin claimed, because of channeling, it worked on both up and down strokes. I have tried to get a fin efficient on the upstroke for years and it just is not even close to the power on the down. Try it sometime. The upstroke even has a tendency to slow you down!

Some companies have 7 or 8 fins in their catalog each claiming to be the best. Then there is the fin designed for the economical diver but still giving total performance without losing quality, and at only $ 49. Maybe that’s the price for just one fin. Why would I want to spend $149 if the $49 pair gives “total” performance and quality construction? Marketing!

Another fin was supposed to stop side slip, a most important thing underwater. Once when I was admittedly exceeding all underwater speed limits, I saw a coral head coming up very fast and tried to swerve hard to the left. The side slip sent me crashing head over heels into a bank. That side slip! I am really glad there were no underwater police who saw this. I didn’t file a report either. The fin also had maximum water displacement. Maximum compared to what?

I have always liked those tiny little inky binky fins called stabilizers on top and in some cases on the bottom of the blade. Cute little things but are they worth anything except a few dollars more to the cost? Maybe if they looked like a ’57 Chevy or how about a ’59 Caddy – night ID lights and all…! I have used fins without them, with them on top, bottom, top and bottom and have found absolutely no noticeable difference whatsoever. It is the person using the fin, not the fin. I didn’t spin in circles nor rock myself to sleep without them.

There used to be a pair of fins with 3 vents and little flaps that covered the vents so on the downstroke (the power stroke) the vents opened and on the useless upstroke they closed. There was some great engineering! Another company had covered channels, pipes so to speak, running the length of their fin blade. No idea what they were supposed to do but I am sure someone came up with an answer to market them. They also had those little fins on top and bottom. And what about triple battened, graphite reinforced Kevlar killer fins? Its still all in the user.

It seems fins are going the same way sneakers did many years ago. Remember when you just bought a pair of Converse All Stars or even a pair of Keds? Now there is a sneaker, I’m sorry, an athletic shoe, “designed” for anything anyone could hope to do. Whoever comes up the wildest looking pair with all kinds of different color inserts and doodads sells the best. There are now fins with movable pieces of plastic, weird shapes, slots and slits, holes and buttons and on and on. Yes marketing has certainly taken over practicality and what really works.

Perhaps the most interesting description was a fin with concave side ribs which controlled rocking motion (I guess we would all get seasick otherwise) by allowing the vector flow of channeled force to be displaced equally along a longitudinal cross margin of the resistant hydro-dynamic ratio, at least that is the way I understood it. If none of that makes sense, then the formula of how it is established obviously will. 4X(bc-3y)+2a+b+c=Force Area Kinetic Energy, known as FAKE in the professional circles. See it really is simple and I am sure your fin kicking has just improved dramatically.

At a dive show, one manufacturer had a tank of water with a really cool looking aluminum mechanical leg, lots of tubes and struts, which was powered by air or something. It hissed and moved up and down and water moved around and all kinds of great things, thus proving that particular fin to be the best there was. But was the user? I asked if I could have my legs replaced by two of those aluminum babies but they said it would cost too much. I really wanted to have the best fins on the best legs. Just think, no muscle cramps.

Now the latest marketing strategy says there is a fin that acts like a propeller on a boat. Sorry but there just isn’t any way the physics of a propeller can be remotely compared to that of a dive fin on a human being. These are two completely different things. An article in one of the outdoor type magazines proved how great these fins were by telling the story of 4 divers, one of which was an experienced diver and a green beret. All four saw a manta ray but only the three with the super fins could keep up while the green beret fell behind. Nothing was mentioned if the green beret was 75 years old and 200 pounds overweight. Don’t trust the word “experienced”either. If I have two dives and you have one than I am twice as experienced as you are. Marketing!

There is an advertisement for a super dooper fin which has something or other on it to end ankle torsion. What the heck is ankle torsion? Torsion is defined as the twisting or wrenching of a body by the exertion of forces tending to turn one end or part about a longitudinal axis while the other is held fast or turned in the opposite direction. So if you are wondering why you and every other diver, at the end of the dive, have your feet on backwards, this is why. Personally I can only walk backwards now because of years of ankle torsion while diving!! A 5000 horsepower dragster has torison as it tries to twist the frame in circles – but divers? Somehow I get the idea that we are all supposed to be able to swim at around 135 mph underwater or kick at 250 udpm (up down per minute).

Some companies try to market scuba fins and snorkeling fins as different things. For that reason many people new in the sport think fins with closed heels are for snorkeling and those with straps are for scuba only. I guess I have been snorkeling with a tank on my back at great depths now for a few decades. There just isn’t such a thing as a purely snorkeling or diving fin. (Same goes for masks.)

Seriously, the best fins I ever wore were the cheapest that one company sold. It wasn’t that the fin was far superior to any other fin. The main thing was I was used to them, wore them enough that I got to know exactly how to get the most efficiency from them. Eventually they tore from use and I went to a different fin, my old style no longer being made. I had to start all over again getting the best efficiency from the new fins. And they did require a slightly different kick.

Fin choice is very subjective. I had a diver come into my shop, pick up a pair of fins, gave them a once over and said they were way to flimsy in the blade. 30 minutes later an unrelated diver came in, picked up the same pair and said they were way too stiff! I always thought they were sort of in between!

For me, it isn’t as much the fin design as the person who is using them. The “best” fin in the world isn’t worth a nickel if the person using them can’t kick. I watched one diver, with knees bent nearly 90 degrees, fins back at another 90 degrees, push their legs back and forth, more or less using the thin leading edge of the blade as the area for propulsion. Cheap fins or $200 fins, that diver simply could not kick and no fin would improve it.

Think of a fin as a large paint brush. Like painting, only the end of the fin, let’s say maybe 5 inches or so, is where the most power comes from. Think of a barn door behind you and you want to get good coverage with the fin. Nice straight strokes up and down. Just like painting. The brush is always on the work. Don’t try to cover a 6 ft. stroke with each kick. Just a nice up and down motion. Keep experimenting. Maybe a slight flex in the knee. Maybe a different angle at the ankle. Maybe both. I now have my kick to where, under normal conditions, I just roll one ankle of one foot. I can move along as well as some who are kicking like a mad horse. It is all practice, trial and getting more efficiency. It is easy. You just have to give some thought as to what is happening at the end of your feet.

Although it is not possible to watch yourself kick, you could have someone video you and watch that. You can certainly watch all the other divers and see what they are doing. And you will see many different uses of fins. Some bad, some good. Look and learn. Squeak out just a tad more efficiency each time. Make sure when choosing a fin, marketing hasn’t outranked technology. No matter what a manufacturer claims, there is no machine which measures force, displacement, thrust, power, decrease in air consumption and so on and so on. Testing is done mostly by humans and therefore both highly subjective and variable.

Bruce Bowker

Share