Fins and manoeuvrability

[Eric Sedletzky]

REVAN beat me to it, but I thought the same thing about the illustration that Sea Rat posted.
The device doesn't measure the drag caused by different gear and how that affects fin performance at all different speeds.
What I thought would be a good test of drag would be to use one of those swimming tread mills that's basically a swimming pool that has moving water flowing through and you swim in place. I'm sure everyone here knows what I mean.

I would load up a diver with the latest biggest fattest puffiest poodle jacket and have them in a prone position as if they diving and travelling forward, but don't have them do any finning at this time. I would hook a cable or line to them somewhere up front and run it to a meter similar to a fish weighing scale so that when the water started to move the diver would just be laying there underwater breathing and the drag could be read as poundage on the meter at different water speeds.
Then take the same diver, except strip off the poodle jacket, totally minimize and clean up the configuration and redo the test at all the same water speeds and see what the difference is as far as resistance.

With this drag test knowledge, a fin test could then be performed in the same tread mill pool without a cable. The diver would have to fin in place with all the same gear configurations at all different speeds with all different style of fins. This could be done over several days using the same diver, making sure the diver ate the exact same meal everyday at the same time, the test was done at the same time each day, the diver got the same amount of sleep each night, etc. This would set a data point as accurately as possible. After a certain time frame in the pool (lets say 1/2 hour of finning at a certain speed), the gas usage could be measured along with all other data gathered to come up with what fin works best for this diver with what gear at what speed. But then this date would only be good for the one diver, other divers may have entirely different results, but doing this test over time with as many test divers as possible would begin to set a pattern which could then also be tracked.
The beauty of a water tread mill is that the flow rate could be set and would be the most accurate way to measure water speed. The only thing the diver needs to do is make sure to stay moving in the middle of the pool.

I would bet that at very slow speeds (the average tropical looky-loo just having fun slow cruising) the gear configuration would make almost no difference with several or most fins. As the speed increased many fins would simply drop out of the test because they would not have enough power or thrust to go beyond a certain speed, especially with a high drag configuration. With the minimalist configuration more of the low end fins would get a little higher on the scale but would soon not be able to keep up and drop out of the test. As speed increased up to high performance levels this is where the dramatic differences in high drag to low drag configurations would be most apparent. With the highest performing fins a high drag configuration would be very hard on the diver and I doubt they could maintain a high speed for long. Take that same fin at the same speed with the same diver with an absolute minimal configuration and I'll bet they would last a lot longer and use way less gas.

 

[Johanan]

..Force Fins do not have any "heft" on the up-kick at all. ... The frog kick, which I tried in two ways, had mixed results. If I kicked the traditional breaststroker's frog kick, with the bottom of my feet, the Force Fins collapsed and provided very little kick force."

Well, this is exactly what I thought when reading about the FF's design which "eliminates" the up-kick.

 

[danvolker]

Well, this is exactly what I thought when reading about the FF's design which "eliminates" the up-kick.

Actually, it is some "specific models" of FF that eliminate this. Their Excellerating Force fin, lessens the power required for up kick, and does deliver some thrust on upkick, particularly with dolphin kick.

I believe the thinking of Bob Evans( creator of FF) was that the biomechanics for humans is that most divers would have strong quads and "relatively" weak hamstrings.....think about the muscles used in walking....the quads hold the whole body up, where as the hamstrings only pull slightly against a weightless leg as it suspending mid-gate. Particularly with the Original Force fin, Evans wanted to make fins for divers that do not train like competitive athletes--people that could kick far more effectively, if the fins used the power that they had already trained every day of their life ( walking).
The specialty fins like the excellerator, are made for different people than the Original FF's were made for..people with different conditioning of leg muscles.

 

[Eric Sedletzky]

If somebody wants to train and build specific muscles for more advanced fins I would recommend doing hamstring curls, hyper extensions, and calf raises. Some leg extensions (quads) and squats would also be beneficial.
Then of course cardio.
Most people who dabble in diving won't do this, all they do is complain that certain fins hurt their legs or feet and give then cramps, so they continue to downgrade the power until it doesn't hurt anymore, instead of getting in shape and getting used to better fins.

 

[John C. Ratliff]

If somebody wants to train and build specific muscles for more advanced fins I would recommend doing hamstring curls, hyper extensions, and calf raises. Some leg extensions (quads) and squats would also be beneficial.
Then of course cardio.
Most people who dabble in diving won't do this, all they do is complain that certain fins hurt their legs or feet and give then cramps, so they continue to downgrade the power until it doesn't hurt anymore, instead of getting in shape and getting used to better fins.

Agreed, but what about simply putting in time with the fins in the pool? Finswimming is both a competitive sport, and a means of fitness. I have for decades swam in the pool for exercise, and have used full-foot fins as a part of that. That way, your legs are ready for using fins in the open water. You can practice with both a flutter kick and the dolphin kick, and start to understand the difference between the two kick styles. The frog kick is also available in the pool. Underwater swimming can be accomplished too, for a set distance (say 25 yards/meters) so that SWB is not a factor. I also have a "training" monofin, one that is not so wide, that I have used for many years. But whichever way you do it, good diving experiences does require a diver who is fit.

One thing about fins that some have not yet discussed is ankle flexibility. Fins are designed with certain parameters in mind, and some are relatively "straight" (without an angle to the foot pocket), while others have an angle to the foot pocket. People with good ankle flexibility can use straight fins, and that's where people who dove in the 1950-1970s were; many were former competitive swimmers with great ankle flexibility. You can see this with this diver from the 1950s, using the straight Duck Foot fins:



Note that the line from his tibia (lower leg) and ankle are a straight line. If I point my toes, I can actually get a negative angle, which gives fins a better "bite" to the water. You can also see this in this photo I took of a diver in Alexander Springs State Park, Florida in 1967:



The original Force Fins actually have an "up" angle, so that even when the toes are pointed, they are not horizontal with the shin bones of the lower leg. But this is by design, as they have tremendous elasticity. This necessitates the hard-downstroke, which bends the Force Fins back almost to vertical and provides their propulsion. This upward bend also allows walking forward with these fins on land. But until the diver really understands the biomechanics of the Force Fins, and modifies what Dan calls the "kick shape" (s)he will not get the results that these fins are capable of delivering.

SeaRat

 

[dmaziuk]

Agreed, but what about simply putting in time with the fins in the pool?

Requires easy access to a pool. I wonder how many people actually have that.

Ankle flexibility is one thing you won't get from doing leg curls. The other one is lateral stability: the part where fin blade tries to twist your foot off as you kick, the splits' big selling point. Controlling the roll works small muscles in the foot and I think outside of the calf as well. I'm not sure what exercise would condition those, but if you don't you get cramps.

(I happen to believe there's ultimately only one kind of fin that provides power, control, and manoeuvrability, and it's called "swimming laps in the pool".)

 

[danvolker]

As most here know, I like cycling as the primary training for fin swimming....it is easy for many people to get access to a bike and a road they can train on....if not, then the pool starts to look pretty good

For cycling though, it can't be just riding a beach cruiser....It needs to be using clip-in pedals so that you can push the pedal forward on the top half of the rotation, and with the other leg "pulling" the pedal backward, like you are trying to scrape sh*t off the bottom of your shoe.
Also, the ideal pedal shape for diving, has the toe pointing downward at the bottom of the pedal stroke...meaning a high seat position...You don't want to pedal flat footed. This provides training to all the muscles we use in fin swimming, with the ideal flexibility and core strength for the movements.

Take a look at the kind of cycling most ideal...Velodrome or Track racing. The take-away, is not that you need a velodrome, just that you need clip in pedals ( or bear traps), and you do intervals of explosive sprints, followed by long intervals of easy riding. This interval approach is what track racers do, as well as crit racers ( though criterium racers do far more total miles per day than track racers). Since Divers will practically never need more than 4 minutes of high power kicking, the track sprint concepts are most ideal....and the muscles created from this, allow ease with the biggest and stiffest fins, to the point that the biggest and stiffest fins, feel like noodles.
When this track trained diver is diving at normal or slow diver speeds, his/her muscles are barely firing, and heart rate/breathing rate are at the lowest they can be. And even the most aggressive fins, feel like easy kicking fins, regardless of what this diver is doing.
See the example of the motion and muscles used in a track sprint :
[video=youtube;Ulj5x3wZqeQ]https://www.youtube.com/watch?v=Ulj5x3wZqeQ&[/video]

 

[John C. Ratliff]

Dan,

First, thanks for the video on the velodrome cycling. It was fun to watch. I am a bicyclist too, and will be headed out in about half an hour to the Health and Science High School for same AVID tutoring. I get about 1,000 miles a year in cycling.

But saying that, I don't think cycling is the ideal exercise for diving, although it is accessible to just about everyone. Finswimming is that exercise. Cycling, even at the competitive level (my son competes in velodromes) does not promote the ankle flexibility needed for efficient finning. I just looked in the magazine, Dive Training, and fully half of the divers in the photos cannot point their toes to horizontal with their shins. Here's a video on finswimming which illustrates why I feel this is the ideal exercise (even if not on the competitive level, or with the monofin):

[video=youtube;brrEpkdAscE]https://www.youtube.com/watch?v=brrEpkdAscE[/video]

Stop this video in the underwater scenes, and look at the angle of the top of the finswimmer's feet to the shin--there is no angle, as the line is continuous. This is important to good finning technique (or as Duckbill would say, flippering technique--"fins are for fish, mammals have flippers").

Here is a monofin tutorial:
[video=youtube;7-5q2Hb0zJo]https://www.youtube.com/watch?v=7-5q2Hb0zJo[/video]

I'm curious, now, as to whether the frog kick is now promoted for all diving (not just technical wreck/cave diving, where it is necessary) because of the limitation of today's new diver's ankle flexibility?

SeaRat

 

[scjoe]

I agree that cycling is not the ideal exercise for finning. The movement patterns are quite different. Cycling is not commonly used by swimmers to train. There is probably a reason for this.

 

[OldNSalty]

I feel bad for the OP.....