A FEW (RELAXED) CONSIDERATIONS ABOUT FINS

Speaking about fins my first consideration is... before thinking about which fins style and shape better adapts to you, train on the development of proper kick techniques, learn how to maximize (but also control) propulsion while minimizing physical exertion and consequently air consuption, focus on trim and buoyancy. At this point, the shape of your fins will be just a secondary problem.

During our Open Water course we realized that there are basically two macro tipologies of scuba fins (here I am not even talking about light open heel fins to be used barefoot as I consider them snorkeling fins not suitable for scuba activity):

1. foot pocket fins;
2. open heel fins with strap, to be used with neoprene boots.

The first category can be worn also bare foot and may seem a good solution for hot tropical environments, also because they are generally lighter and easy to pack in the luggage. All of us did use them at least once in our life, in the swimming pool or by doing snorkeling.

Nevertheless, if you are seriously into scuba diving I suggest to leave this kind of fins to snorkelers and always go for open heel fins and neoprene boots. You will soon recognize the advantages of this solution:

1. the rubber sole of the boots offer extra stiffness to your kick, transmitting the energy in a more direct way to the blade, thus maximizing the propulsion;
2. boots seat better in the foot pocket, tightly secured by the strap, and you do not risk to lose the fins as it may happen with lighter foot pocket fins when you kick too hard;
3. boots protect your feet from excoriation caused by the contact of your bare foot with the rubber foot pocket;
4. neoprene boots can be used as normal shoes and offer protection while walking on the boat or on the shore;
5. boots guarantee extra thermal isolation.

One word about the strap: open heel fins are distributed with a large variety of straps. By choosing your fins, you are also choosing your strap: make sure that the strap is of the right size of your foot, opt for one piece rubber bands or better iron springs, avoid adjustable or expanding plastic clip buckles that are often fragile and soon or late will break as well as bungee cords that are more likely to wear out by the use in salt water.

Finally speaking about fin design, in the mega expanded universe of market offer it is possible to identify main 5 categories, based on the blade shape.

Paddle fins: generally optimized for flutter kick, they represent the simplest design and basically display a blade directly attached to the foot pocket. Most models are mono or bi-material (plastic + rubber). Paddle fins often have different inclinations between foot and blade for optimized kicking angle. Many bi-material blades are designed with two or more channels that funnel the water flow along the whole blade length, improving propulsion.

Jet fins: technical fins by definition, optimized for frog kick technique. With the exeption of very few models they are prevalently made out a single rubber mold (thus very heavy) and display vents on the blades that have the purpose of minimizing the mechanic resistance of the water in the kick loading phase.

Split fins: thought and designed to make flutter kick less exhausting, split fins offer the same propulsion of paddle fins but with less strain. Basically the split, when you kick, creates an open angle in the blade that causes a pressure disbalance which “sucks” the water along the whole blade length, minimizing the effort but keeping the propulsion constant. Basically useless if used with frog kick technique.

Hinge fins: Recent design concept, the blade is connected to the foot pocket by a hinge. Developed in aquadynamic flume, this fin has been thought to reduce stress and strain in the foot ankle while mantaining good propulsion. In my – personal – opinion this is more a marketing claim rather than real and concrete measurable advantage.

Force fins: niche product, designed to imitate the tail of marine animals, used with flutter kick they offer a very good propulsion. Very good fins for walking on the boat. Not performing with frog kick and ridiculously expensive.

📸 Stefano Festini

Now that we learned something about the market offer, it is time to choose the right fins. Here some food for thought:

• choose the fins according to your personal kicking technique: if you practice only flutter kick, jetfins will not be performing and as anticipated, split fins will be almost useless if you try to do an helicopter turn;
• consider the kind of exposure suit you will use: many drysuit divers prefer to use very heavy jetfins in order to balance the slightly positive buoyancy of their legs given by the drysuit. On the contrary, using heavy jetfins with a 2 mm shorty could lead to feet down or dropped knees trim;
• this leads to the next suggestion: always consider the weight of your fins and its impact on your buoyancy. You may find very similar fins models and shapes distributed by different brands with very different weights;
• remember that wearing the wrong fins causes more strain and possibly cramps, so it is worth to invest some time and trial dives to find the right fins.

Conclusions:

• always choose a combination of open heel fins + neoprene boots;
• learn different kick techniques and try different kinds of fins;
• fins play an essential role on your trim. Study your position and your weight; distribution, choose a fin that helps you mantaining an horizontal position.

If you still do not have clear ideas, I suggest to opt for the simplest bimaterial paddle style channel fin with high and stiff sidebars that you can find. This solution offers a good compromise between propulsion and comfort and allows very good control also in case of frog / back kick and helicopter turn.

One last word about freediving fins: although some scuba divers use them, I suggest to avoid long blade freediving fins. They are specialty fins, and their long flexible blade offers high propulsion and minimizes physical exertion only in combination with the proper kicking technique. Moreover in our OW course we learned that in the water we want to move as less as possible so manoeuvrability, and not propulsion, must be our primary focus. In fact, using freediving fins in bigger groups may result clumsy and their long blades could lift lots of sediments. Eventually, long blades use a lot of space on the boat and are most likely to damage by giant stride entry.

And you? Which fins do you use, and why?