How do the vents actually work?

[Rick Murchison]

So far as I know, every machine study (where the fins were put on a machine that attempted to duplicate the human kick) that measures thrust and effort has concluded that vents and splits are just so much window dressing.
On the other hand, study after study using actual humans conclude that vents and splits do influence fin performance.
Whatever trips your trigger.
My personal favorite is the Cressi Frog. I own and use Jets for caving and wrecking as they are a little shorter than my frogs and so give me a little tighter profile in confined spaces, but my opinion is that the vents do no good (and no harm) for me.
S

 

[SangP]

Hi WD,

It cost a lot to make a mold and why change it if the performance is roughly that of the orginal jet fins?

The way I see it is that companies are reluctant to use the same design due to pride in their own product, what would customers say when the fins they bought a couple of months ago are now replaced by a design exactly the same as the competitor's fin?

Another reason why I don't think vents and splits are measurable on machines is because the machines kick exactly the same each time making very little error in using the fins and water spillage is reduced.

Also I'm not sure how they measure power used and unless you can measure exactly the power/water displacement/most effective kicking style for each and every fin, most tests are not really accurate. We adapt our kicking styles to the fin used and can maximise the effectiveness of the fins, machines cannot do so.

We don't kick the same always and we make mistakes when we kick we may feel that vents/channels/splits work because these designs may help overcome our mistakes and help channel water better... ?

Whatever the case is, if you are confident of the fins you are using, then why change it? I personally know of a diving instructor who would challenge anyone to use any fins agains his jets and seem to always win in speed tests... go figure.

SangP