Freediving fins: bi-fins, the monofin, hyperfin, Lunocet and DOL-fin monofins

Freediving fins: bi-fins, the monofin, hyperfin, Lunocet and DOL-fin monofins

Maybe you used ancient scuba fins (short bi-fins like in the above photo) when you did your first dive, or maybe you bought a cheap pair of bi-fins. When you start going down longer, deeper, and start feeling your legs burn on the way up it may be time to rethink your propulsion and get a proper pair of freediving fins. There are many options, from plastic bi-fins to carbon monofins to aluminum DOL-fins. Here are some of the things to consider when you buy a new fin, or pair of fins.

What are you using your fin for and where are you using it?

If you are spearfishing, you are going to have very different requirements from a fin than if you are purely doing competitive depth dives. Depth divers do not need the agility that spearfishers need, and are fine if they can just go up and down in a straight line. Spearfishers (and harvesters) need to be able to navigate kelp forests, reefs, occasional overhead environments and therefore need different gear. You will not commonly see a spearfisher with a monofin, although I have heard of one with an Orca Dol-fin. Spearfishers and recreational divers nearly always have a pair of bi-fins.

Also think of the water temperature when you are buying fins. In Canada, we dive with at least a three millimeter neoprene sock, more often with a 5 mm. This will mean you need to get a different size. In the tropics, you might be fine without neoprene socks.

Monofins and hyperfins are good for depth diving. A hyperfin is a monofin with a blade that is angled with respect to the foot pockets, and usually with reinforced edges (so not merely a triangular plastic, composite, or carbon flap). Consider a hyperfin an upgraded version of a monofin. Hyperfins and monofins are more efficient than bi-fins and require an all-body motion in order to get a good kick. They work optimally under a very narrow range of kicking amplitude, and are not great for surface swimming. Again, not a problem if you are a depth diver, but it may be problematic when spearing or sub-optimal when doing recreational dives. Another important difference with bi-fins is that you will not be as good of a buddy in a monofin. Helping an unconscious person in the water is much easier with bi-fins

Recreational divers are in between the demands of a depth diver and a spearfisher. They like to navigate rock reefs and overhead environments, so need more agility than a depth diver. However, they do not need to be worried about entanglement the way a spearfisher does. Recreational divers can use any type of fin but most commonly use bi-fins.

The safety diver in the foreground uses bi-fins, the diver uses a hyperfin. Photo from Jahyem, CC BY
The safety diver in the foreground uses bi-fins, the diver uses a hyperfin. Photo from Jahyem, CC BY

 

Freediving fin materials

Fins come in different materials. The cheapest and sturdiest is plastic. It is unfortunately very inefficient. Composite or fiberglass is one step up, and is a bit lighter and more expensive. Then comes carbon. A good fin is carbon and you should be able to buy it with different blade strengths. The blade should not bend more than about 45 degrees at normal kicking strength (with any material), so make sure you buy a blade stiffness that is adequate for your leg strength. If your fin bends too much or too little it loses its force and you will lose efficiency. If you are fairly light and have not got a lot of strength in your legs get a light blade. If you are heavy and muscular, get a stiff blade.

Hydrofoils: the future is here

[Edited in light of new information in December 2015] A foil is a wing shaped object, and a hydrofoil is a wing shaped object to be used underwater. Hydrofoils like DOL-Fin monofins and the Lunocet do not bend themselves (though I think the flukes of a lunocet do), a large difference from bi-fins and mono-fins. Rather, they depend on a suspension system that allows the blade to change angles. Both the DOL-Fin monofins and the Lunocet can be disassembled in order to make them easy to transport.

DOL-fin monofins

The foil of the DOL-Fin is aluminum. The DOL-Fin Orca model has a foot binding strap system and fairing to streamline your feet for better swimming performance. It also has added buoyancy, which will keep you horizontal during your breathe-ups. The DOL-fin X-20 and Pilot are used with biking shoes, and this may be a good option for those with difficult feet (like me). The creator of the Orca DOL-fin (Ron Smith, see below) is working on different sizes. I know a few owners of the DOL-fin Orca and they are very happy with not only the product, but also the customer service. Unfortunately all DOL-fins have been taken out of production.

The Orca Mk 1 and its proud creator.

The Orca Mk 1 and its proud creator.

 

And the improved version; the Orca Mk 2
And the improved version; the Orca Mk 2

The Lunocet

The Lunocet is the first biometric monofin available, modeled after a dolphins’ tail. The Lunocet is used with biking shoes and has a sophisticated suspension system that can be set to three different resistances. It can be disassembled to a smaller package than DOL-fin monofins (which have one long hydrofoil) because of the two separate flukes. It is competitively priced at 399 USD. This price is similar to that of carbon-blade bi-fins and monofins.

When I initially did my research for the Lunocet and asked around in Facebook Groups and forums it seemed like the customer service was not up to standard. I heard stories of backorders and orders that were not fulfilled. After speaking with the current distributor of the Lunocet, Jeff Watson, I found out that the distribution of the Lunocet changed hands in November 2014. Jeff understands that the manufacturer still has some of his own back-orders to fulfill from before November 2014, when Ted Camillio (the designer of the Lunocet) fulfilled his own orders directly. However, from November 2014 onwards Lunocets have been delivered worldwide and in a timely fashion, according to testimonials on www.ultimateswimfin.com, the new distribution channel. The testimonials are sourced from social media and some testimonials are from verified reviewers meaning that these are real people, with real social media accounts)

lunocet

The Lunocet

Pros and cons of different fin types

Bi-fins (80 – 200 USD for plastic or composite, 200 – 600 USD for carbon). Pros: versatile, agility, ease of transport. Cons: not as efficient as other options. Brand options: Mares, Cressi and Omer are sold in many online stores.

Monofins and Hyperfins, 150 – 300 USD for plastic, composite and fiberglass. 200 – 800 USD for carbon blade. Pros: Cheapest option specific for depth diving. Hyperfins are upgraded monofins with footpockets angled w.r.t. the blade. Cons: not good for surface swimming, only one amplitude. Brand options: Leaderfins, Waterway, and many more.

DOL-fin monofins (599 – 1200 USD). Pros: Extremely efficient, good for both depth and recreational diving. There are three types available. Indestructible compared to other fins. Can be disassembled. Cons: Heavy, not very good for penetration or kelp forests, expensive. No longer available.

Lunocet (399 USD). Pros & cons? Please leave a comment!

personal experience

I used Cressi short bi-fins (scuba fins) for the first year that I dove. I did my first 30+ m with these, but after a while did want a better fin. I opted for Cressi Gara Professional bi-fins, made of plastic. They were better, but not as much of an improvement as I hoped (they were also the cheapest I could find: 80 USD). I did my first 40 m dive with these fins, but would get burning legs on any deep dive. I have only used monofins for pool practice, and never liked them very much. Then I switched to an Orca DOL-Fin Mk 1. A second hand modded with extra buoyancy, this fin was a project fin when I bought it and made me feel like a drowning caterpillar the first time I used it. After some additional mods and some practice it boosted my diving like nothing else. My bottom time has increased and my average operating depth has increased. I have not had burning legs coming up after any dive, while diving repeatedly to 30 meters. An additional advantage is that the Orca has added buoyancy, making for an extremely relaxed breathe-up. However, I am not as fast as a buddy and I have been a bit stuck in a kelp forest once. I have entered overhead spaces and as long as they are wide enough, it works well. For spearfishing around reefs, harvesting, and tight spaces I would not use the Orca but revert to bi-fins.

My only personal recommendation: spend as little as you can on your first pair of fins. Find out what you want in a year or two of diving and then go all out.

Freedivewire.com is not affiliated with any of the products listed on this page at the time of writing.

 

Jaap

Jaap is a geologist by trade and a freediver by passion. Jaap wrote the book Longer and Deeper in 2018. His book teaches how to train for freediving and spearfishing on land.

This Post Has 4 Comments

  1. Fondueset

    I’d like to make a couple of small corrections – First, in general, soft blades are the rule for endurance and most recreational diving.
    Hard (also known as ‘sprint’) blades are for depth. Of course you also tune your blade stiffness to body mass and diving conditions – but in general you’ll want to start a soft blade in order to not burn too much energy.
    Also – a good custom hyperfin – with fiberglass blades – will run around $600us with shipping.
    Carbon fiber adds about $100.
    The biggest challenge with a custom hyperfin is fit. These fins were originally made for fin swimming competitions and, for that activity (as well as depth competition) force transmission trumps comfort. For recreational free diving, comfort is more important – you want a fin you can wear for more than fifteen minutes without your feet bleeding – this takes some research.

    1. Jaap

      Hi Fondueset, thank you for your comment. Regarding the softer/stiffer blades, I think that the efficiency of a blade is the first priority, and this is dependent on the angle of attack. A perfect angle of attack can only be attained if the blade stiffness is chosen appropriately for the kick strength. If you are using a softer blade purely to conserve energy, you will only be able to use it efficiently (the same perfect angle of attack) with a softer kick. And that simply means that you won’t go down as fast.

      1. John

        Hi Jaap,

        Thank you for this great article. Very informative and easy to read.
        I’m just starting out so like you mentioned – I will be starting with scuba fins as well.

        All the best,
        John

        1. Jaap

          Hi John, I’m happy to hear you found it useful. Enjoy your time in the water!

          best,
          Jaap

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