Towards a full-foot fin length classification system

[DRW]

I haven't posted in a while, so I thought I'd begin with a new thread. One of the perks of retirement is that there's a little more time to ponder the more ethereal issues in life, and one research question that caught my attention was where long freediving and spearfishing fins belonged on the spectrum of closed-heel fins from the shortest swim workout fins to the longest giant-bladed fins.

When considering this issue, I did a search of the Deeper Blue forums and found the short thread entitled "Blade Length" at
http://forums.deeperblue.com/threads/blade-length.85465/#post-795537
useful. I agree that fin length is only one variable in fin selection and probably not the most important one, but for the general public it remains one of the most obvious characteristics of any fin.

When I began the research, I found that Far Eastern sources were much more forthcoming with fin length measurements than Western ones, hence the examples below. The overall length of fins were also given more frequently than blade lengths. Then there was the problem of the considerable difference between the overall length of the smallest foot size in a particular model of fin and the overall length of the largest size in the same fin model. The problem was compounded by the fact that some fins come in a huge range of foot sizes, while others are available in a a very narrow range of sizes. I resolved to compare overall fin lengths based on European size 44. This is what I've come up with so far:

Length 1: Short-blade training fins (ST): 0-340 mm (size 44)
Example: 89A

Overall length: 335 mm

Length 2: Medium-blade training fins (MT): 340-400 mm (size 44)
Example: AFF08

Overall length: 360 mm

Length 3: Long-blade training fins (LT) / Short-blade diving fins (SD): 400-500 mm (size 44)
Example: Dolphin

Overall length: 490 mm

Length 4: Medium-blade diving fins (MD): 500-650 mm (size 44)
Example: Supermew

Overall length: 615 mm

Length 5: Long-blade diving fins (LD): 650 mm and over (size 44)
Example: Barracuda

Overall length: 780 mm

So that's as far as I've got. Do you think that there ought to be a "Length 6", perhaps starting with a EU 44 fin length of 800 mm, or even more fin length classes, when taking into consideration the freediving/spearfishing bifins currently on the market? I'd be interested to hear anybody's constructive views.

 

[vali]

I don't know if my post is constructive or not, but I can tell you that are bifins longer than 800mm
for example my bi-fins are Seacsub Shout 900 and each blade has 900mm in length

If I misunderstood your thread purpose, please forgive me!

 

[DRW]

I don't know if my post is constructive or not, but I can tell you that are bifins longer than 800mm
for example my bi-fins are Seacsub Shout 900 and each blade has 900mm in length

If I misunderstood your thread purpose, please forgive me!

Very constructive indeed, Vali. Thank you. I just wanted to know how very long freediving fins might fit in to the system I outlined. Sounds like I might indeed need a "Length 6" if the blade alone, without the foot pocket, is 900 mm! So would the example I gave, the Barracuda pocket + blade, at 780 mm be considered a relatively short freediving fin?

 

[vali]

Well, my fins are 900mm - foot pocket included!
But there are fins [seac sub shout S1000] who have 1000mm length [footpocket included]
And I definitely saw bi-fins longer than 1000 mm!
Generally you can find this sort of things by searching the well-known brand, because they give also the length in the tehnical specs...
[cressi; mares; leaderfins; specialfins; seacsub, etc]
And yes! the Barracuda at 780mm is a relatively short freediving fin

 

[vali]

I want to tell you, however, that looking at the Barracuda posted above by you: it looks like they are [only] rubber based fins
So perhaps for that kind of technology there are not so short...but this kind of fins are obsolete for obvious reasons
The rubber fins are very heavy comparing to those in fiberglass or carbon based, so I guess, make them to long was not an option at the time...
I dove with free-diving rubber fins in my early age and I can feel even now theyr heaviness

 

[DRW]

Thanks, Vali, that's a big help. I'm a bit of a traditionalist when it comes to fins and the Baracuda fin seems to be a favourite with Japanese freedivers and snorkellers, not least because it's manufactured in Japan by Gull, which just makes rubber fins. Despite the material, Barracudas are very expensive fins, priced at hundreds of US dollars...

It's a valuable point you made about other materials opening up the possibility of even longer blades. Looks like I have some more research to do, to find the longest bladed freediving fin and to see whether most or all long modern freediving fins come in the 800 mm plus group.

 

[vali]

I am not a specialist concerning bi or mono-fins suited for free-diving, but the goal is to achieve better results in horizontal or vertical distances in apneea. Those can be achieved with minimum of energy loss, so some heavy fins don't do any good. I saw however rubber fins used in training by free-divers. but never in competitions or in trying to do personal best.
There is yet another reason why the new blades are coming in dual materials: if the blade break, you can replace it with a new one; also if the foot-pocket broke, you can purchase another one and repair the fin. Not all of them can be disassembled.
My previous fins [Seac sub Genesis] wich are shown bellow, has a very simple system and can be disassembled very easy in case that some of the two pieces is broken. The bad issue with rubber fins is that, if the fissure appear in the rubber, they will expand and they finally broke without the possibility of repair...

 

[Bill McIntyre]

I'm not so sure I understand the value of classifying fins into length groups. What is important to me is to know the length of a particular fin compared to some other than I might own or be considering.

But anyway, it it will add to your database, I just measured my Moana carbon fiber fins in a size 44-46 Pathos foot pocket. Total length is 39.5" (1003.3 mm). http://moanawaterman.com

I was previously using Edge fiberglass blades in Picasso pockets, and I had to get a longer gear bag for the Moanas.

 

[DRW]

Thank you Bill. At the moment, I'm just trying to think aloud, looking for patterns between form and function that emerge when fin blade length is regarded as a continuum, with the shortest swim training fins such as Zoomers at one extremity, the longest freediving fins at the other and snorkelling/scuba fins somewhere in between. I'm not expecting this hazy concept to have any immediate purpose or utility, I'm just following an idea to see where it leads, and like a lot of investigations, it all may end up just stating the obvious, but that's the nature of the beast that is personal research.

Thank you too for the specifications of your own fins. I'll take those into consideration as, when and if I develop the length classification system further.