Info What is the "best" fin?

[tursiops]

There are flutter efficiency tests with different fins here.

Testing — Truefin

Only thrust was measured, not oxygen consumption. Rather different kind of test.

 

[tursiops]

That is where I think the greatest opportunity for net efficiency lies for more frequent, low amplitude kicks and fins that best match that style. At least for average humans.

This is the conclusion of the studies I referenced, with the caveat that leg muscles seem to prefer a kick frequency around 1 Hz.

 

[drrich2]

I have noticed a STRONG marketing-effort for FF on ScubaBoard.

Which leads to the question of why they haven't gone more mainstream. I thought maybe it was cost, but considering how many people on ScubaBoard advocate for Shearwater's popular A.I. products (e.g.: Perdix 2, Teric), as opposed to, oh, say, pushing Oceanic Worldwide Geo (whatever version they're on) - though the Geo is reputable and gets some praise, it seems if the product is premium in function divers will tolerate a premium price (but the value proposition has to be there - Atomic Aquatic's expensive BCDs don't seem to've persuaded people here as well, and debates over their most expensive regulators' value come up fairly often).

Force fins are not bad fins, the best use in my opinion is where you have distance to travel and don’t want to be tired out or cramping when you get there, the military like them for that and they are compact.

All fins require different techniques and it takes some water time to find what works for you. The FF works for frog kicks but not very well, the frog kick uses the opposite of its design parameters so they can function that way but best used in a more limited fashion.

Good to hear. My questions would be:

1.) How good is it for the average diver flutter kicking at a leisurely pace on a typical guide-led Caribbean reef tour dive? Or a Bonaire shore dive?

2.) How good is it for flutter kicking into mild to moderate current? Again, assume the average diver, not an athlete with strong legs and excellent cardio.

 

[tursiops]

My questions would be:

1.) How good is it for the average diver flutter kicking at a leisurely pace on a typical guide-led Caribbean reef tour dive? Or a Bonaire shore dive?

2.) How good is it for flutter kicking into mild to moderate current? Again, assume the average diver, not an athlete with strong legs and excellent cardio.

The research I quoted and summarized is pretty clear:
(1) What fin you choose is irrelevant for using less O2, if you are putering around with a flutter kick; they all perform about the same. What might be different is how they feel, not how they perform.
(2) Flutter kicking into a current -- or equivalently, trying to go fast -- the smaller-blade, more flexible fins are better for weak legs, the larger blade and stiffer fins are better for stronger legs. You just need to kick faster with the smaller fin, which is easier to do since it is not as stiff.

 

[lexvil]

Which leads to the question of why they haven't gone more mainstream. I thought maybe it was cost, but considering how many people on ScubaBoard advocate for Shearwater's popular A.I. products (e.g.: Perdix 2, Teric), as opposed to, oh, say, pushing Oceanic Worldwide Geo (whatever version they're on) - though the Geo is reputable and gets some praise, it seems if the product is premium in function divers will tolerate a premium price (but the value proposition has to be there - Atomic Aquatic's expensive BCDs don't seem to've persuaded people here as well, and debates over their most expensive regulators' value come up fairly often).

Good to hear. My questions would be:

1.) How good is it for the average diver flutter kicking at a leisurely pace on a typical guide-led Caribbean reef tour dive? Or a Bonaire shore dive?

2.) How good is it for flutter kicking into mild to moderate current? Again, assume the average diver, not an athlete with strong legs and excellent cardio.

I would say they would be good for that once you have you kick method down for whichever style you choose, there are a lot of variations in force fins.

 

[tursiops]

There are flutter efficiency tests with different fins here.

Testing — Truefin

Is there a reason the TrueFin website does NOT link to this testing information?

 

[tursiops]

If you think military-contracts and studies are unbiased, I have a multi-billion-dollar arms contract to sell you.

FYI, the studies linked in the OP, funded by the Office of Naval Research, were grants, not contracts, and performed with the legal understanding that the results would be made publically available, peer-reviewed, and openly published. That is how grants work.

 

[GDHLEWIS]

Everyone's got it all wrong, these are the best fins and I will hear no more of it. Sell all your fins and buy these. Techy fin with a boot all in one and stylish...what more is there to want

 

[Truefin]

Only thrust was measured, not oxygen consumption. Rather different kind of test.

There are actually two sets of graphs. You are correct that the first set only measures thrust as a function of kicking frequency, but the second set of graphs measures thrust as a function of the toque delivered to a kicking leg (simulating muscle exertion) that is generating the thrust. It seems reasonable to assume that VO2 consumption would be proportional to muscle exertion.

As stated at Efficiency & Geometry — Truefin
<Testing VdotO2 is rather involved, and as Pendergast noted, VdotO2 may be effected by divers "consciously or unconsciously" altering "their ventilation independently of their VdotO2". For this reason, the Truefin machine tests correlating input power with both kicking frequency and fin thrust may be considered objective tests while omitting human interaction.>

From:
https://www.researchgate.net/publication/10677199_Evaluation_of_fins_used_in_underwater_swimming

< The physics of underwater swimming with fins is complicated, as demonstrated by the
data from the present study showing fins with very different designs can have similar energy
costs of swimming (Attack vs Apollo). Some fin comparisons are reported for swimming at
slow speeds with measurements of air consumption, however due to the low ventilation, the
diver can consciously or unconsciously alter their ventilation independently of their VdotO2.
This invalidates these types of studies. This point was emphasized in this study as the reliability
of ventilation and velocity was very low (r = 0.54), while the reliability of VdotO2 and velocity
was very high (r = 0.94). Fins designed on the basis of physical principles for airfoils or
propellers do no necessarily lower the energy cost of swimming (Apollo vs Appolo taped). This
demonstrates that, based on our current understanding of the physics of underwater swimming
with fins, theoretical models have to be evaluated empirically as was done in this study. >

One thing I am not clear on though is that in the Pendergast paper, the O2 and CO2 fractions in the expired gas were determined using a calibrated mass spectrometer, so why does it matter if the diver alters their ventilation, they are still measuring O2 consumption. But evidently at slow speeds VO2 tests are unreliable.

Joe Maresh

 

[Truefin]

Is there a reason the TrueFin website does NOT link to this testing information?

Thanks for your interest. What happened is while the fin was being developed a public web site was created with technical and engineering information for different people to track the product and background as it evolved over several years. That content became rather large, and after the fin production started the sales people didn't want to clutter up the commerce site, so they took truefin.com,, and the technical and engineering information was moved to a new site - truefintechical.com,,, so the testing information was omitted from truefin.com. There is a link at truefin.com that takes you to the home page of truefintechical.com, but you then have to go to the drop down menu to find the testing information at truefintechical. It's kind of awkward to access the engineering info and in the future we may have to try to streamline the browsing experience.