This is a post by Sanne Buurma.

Sanne swimming with the Leaderfins Flyer mono-fin.

…or actually how we think we should choose a mono-fin. As Jorg  and I were training last week, we tested a few different kinds of mono-fins. We wanted to see the difference between the fins in areas like;

• if they were comfortable
• how they performed
• what the efficiency is
• how the balance is using the mono-fin

The tested mono-fins were three kinds, two were from Leaderfins and one was from Special fins.

1. Leaderfins Freediving Sport
2. Special fins ‘Dolphin‘
3. Leader fins Flyer

Comfort

The first thing to notice when putting on a mono-fin is the difference in foot-pockets. All three mono-fins, differ very much in how comfortable they are when you put them on.

1. The least expensive one form Leaderfins, wasn’t all that tight around the feet. Supposedly making it a good to wear fin as it goes easy on the feet, but the thing to note here is that your feet are in direct contact with the foot pocket – although so it feels.
2. The special fins mono-fin was already a bit more comfortable as the foot pockets are surrounding the feet with a layer of rubber. They have a somewhat tighter fit and in this part of the test they feel they nicest to wear.
3. The Leaderfins Flyer mono-fin has extra tight foot pockets to improve the efficiency when bringing the freedivers power to the water to propel. This is also what you immediately notice when putting them on your feet. They are as tight as you can expect them to be. In the beginning I could only wear them for 20 minutes or less. Over time this seems to be a thing you can get used to, but this is a process we’re still going through.

Performance

Specialfins - Dolphin

Testing the performance comes down to how we feel and see each other perform a good technique with the fin.

1. For me personally the Leaderfins Freediving Sport was the lesser one of the three, because I could totally not feel that any the effort I put in, was going anywhere… In my experience this fin was just dangling from my feet and making me all unbalanced and Jorg’s feedback on the technique was even worse. The other way around Jorg could say the same and I spotted the same lack of technique in Jorg’s runs.
2. This mono-fin already has a way better feel and with proper training it is feasible to improve your technique and thus your performance. For me personally I think I still better of with a slightly harder blade, Jorg could already find a good balance and technique with this fin.
3. The weight in the arch of this mono-fin -about 5 kilograms – makes it easier to control the performance, because once the proper motion is executed the weight is behaving somewhat like a damped movement. Not that the amplitude is dampened, but actually no real peaks and no excessive movements. As if you’re movement is filtered.  Once the fin is set into motion, it feels as if your guided into your next stroke either up or down.

Efficiency
When it comes down to how much force you put in compared to the output that the blade delivers we’re talking about efficiency to see where the least amount of energy is lost into things like footpocket clearance, blade surface, stiffness of blade and rubber.

1. As I mentioned above in the comfort, this mono-fin has a minimal layer between your feet and the blade. Furthermore the rubber used on this fin is supple and the blade is soft. For me these factors are not ideal and proved to be making it hard for me to effectively make a full mono-fin movement. Overall it felt like having to really put all the energy into the blade through the tip of my toes. Which made my feet and ankles hurt after only 4 lanes. Jorg could make easy movements with these fins, but had to agree that you have to put energy into the fin with your toes.
2. The footpockets on this mono-fin are already a big improvement compared to the first one we tested. You feel that more power and energy is put into the blade, but for me the stiffness of the blade is slightly on the soft side. We tested different kinds of techniques on this one; kick-glide & constant kick. Overall Jorg and I both have a good impression about this mono-fin, but the somewhat loose foot pockets and supple rubber still makes us believe that not all of our power was transformed into propulsion.
3. With the 2 preceding mono-fins we’ve experienced foot-movement and supple rubber and soft blades, but this type of mono-fin really excels on the area of efficiency. The arch with added weight, keeps the motion going. The foot pockets are really a tight fit, which makes it feel like all energy put into it is transformed into propulsion. The rubber used for the pockets and arch are pretty rigid, combined with a stiff blade makes this feel like you’re being efficient when executing the mono-fin movement.

Balance

Leaderfins - Freediving Sports

Swimming with a mono-fin is particularly difficult when it affects your balance, Jorg and I witnessed this effect with Sandi Bitenc’s world record attempt last week.

1. In my experience with this mono-fin the balance was very hard to find, because of the toes having to put in all effort. The thing I spotted when Jorg was doing his test runs with this one, the movements to the side were very much present, not looking like a controlled motion at all. This also influenced the position of the upper body making it tilt and roll during the test runs.
2. For me the balance with this fin comes down to putting more exercise into the technique. I dislike the somewhat soft blade, which makes it less controllable for me. But this can also mean a lack of experience in mono-fin swimming from my side. Jorg seems to get away with this mono-fin easily and makes the movement look controlled and balanced.
3. For me this mono-fin was first up in the test runs, making my previous judgments very clear and pointing out that I really have the need for a rigid mono-fin and a stiff blade. From the start this mono-fin makes a normal movement and does not tilt me or roll me over when applying force. After exchanging thoughts, Jorg’s experience after he tested the other two fins was almost the same as I had felt it. Of course we have to put more time and effort into our technique, but this goes for all the mono-fins.

Concluding

Leaderfins - Flyer

To conclude our small test with these types of mono-fins, is that we’re now continuing with the Leaderfins Flyer mono-fin. Not because of the comfort, but of excelling in all other test areas that really matter when doing a distance performance in the pool. Our conclusion on the test areas we picked is that we’ve setup a pretty good test method to find a fin to continue our training. Having tested the different mono-fins, makes us realize that technique is everything with freediving with a mono-fin, not because we’ve just started using the mono-fin, but because efficiency is really all that matters and makes a mono-fin excel the bi-fins for most freedivers.

Next review/test

Leaderfins - Hyper

We’re very keen on testing a mono-fin which features the foot pockets that are placed on the mono-fin blade more, like the Leaderfins Hyper. As we refer to them as rocket-pockets ;). These are more likely to have a better angle for your feet  and the fit should be better, but still in the efficiency area. All these are assumptions are based on feedback we received from the freedivers who already wear them. This will be a topic for the next test/review we do in our quest into choosing a mono-fin for the pool.

Besides the fact that Jorg was on a roll yesterday during training, we tested my new gadget; the Go Pro Helmet Hero Wide-angle camera . This all started with a nice video (click here) we’d seen from our fellow dutch freedivers from OVH. The video images looked so super cool, I just couldn’t resist to get one myself…

Not only does it feature possibilities to mount it on multiple stands and thus on almost any location, but even better it features a small underwatercasing with a specification to a depth of 30 meters. One might think that such a camera must be quite big, but I was very surprised how small this camera is, even within it’s casing.

I ordered the Helmet version from their website, which comes included with a wide variety of mount-stands and straps/bands to wear the camera on a helmet or directly on your head. The only thing I did not order from America were the batteries and the 2GB SD card. As these are also easily bought here in the Netherlands conforming my own battery charger.

The test
While Jorg was doing his static schedule I just mounted the Go Pro Hero camera on the head-band and adjusted it to where I thought it would focus on about 2 meter in front of me. I went down to the 5m deep bottom in the Tongelreep along side Jorg a few times to test a few different techniques. As the outcome isn’t reviewable instantly I did not vary the parameters too much.

After the depth stuff, I did some filming of Jorg’s dynamics with and without fins. Seeing in a result that my arms stroke is getting in the picture like a first person shooter kind of perspective. So adjusting this parameter by freediving with my legs kick only proved to be giving the desired result. Then it was my turn to do some freediving training and Jorg proposed to me that I wear the camera head-band backwards to be filming my leg stroke. Adjusting the camera angle turned out to be tricky and needs some testing to find the proper angle to make a good shot for filming the leg stroke.

I compiled a video clip, featuring the different stuff we recorded during our freediving session last night.

Click here to view the embedded video.

And Saturday we’re going for the Bosmolenplas in Panheel again and I’ll certainly take the camera with me to see how it works in the outdoor environment.

Concluding
This is a great camera which will certainly bring you some fantastic wide-angle shots of anything you want to film. The picture quality is somewhat lower then the standards these days, but then again what more do you expect from a camera that size and all it’s capabilities. The 2 GB SD, which is the maximum size it will allow, is more than enough to do your filming. In our way of using the camera, we’re unlikely to get the SD card full, as that is good for 56 minutes of filming. I didn’t even mention the other capabilities, but read the specs on the website and you’ll know this is a camera you want to add to your inventory, as the price is good compared to all it’s possibilities.

Check out this small video clip in HD ;)

httpvhd://www.youtube.com/watch?v=fLQQQ5fKww8

This is just a short impression clip we shot during the last 2 training sessions (The last run of 1m 30s static schedule of Indoor & Outdoor freediving in Bosmolenplas, Panheel), so far I think the FLip Mino HD can bring us that extra footage we can use in our video clips » enriching the freediving experience like we do in the moment.

Now all we need is a underwater casing for this small and mobile HD recorder, as they only feature an underwater casing for the Flip Ultra.