How do the vents actually work?

[willydiver]

I've owned several pairs of vented fins including the SP Jets I've been diving for a couple of years. I've never questioned the "performance enhancing" properties of the vents in fins that the companies claim, but how do they actually work? They supposedly relieve the leg muscles on the kick return, but how? I'm under the assumption that the quadraceps(sp?) are the strongest, least tiring, muscles used in the kicking motion. The return kick, using your butt muscles, seems to be the weakest portion on a kick cycle. The way the vents are facing, and assuming forward momentum in the water, they seem backwards on the SP Jets of what they should be.

I just don't see how the water is actually routed through the vents and at what point. How does this really help the process of kicking?

Thanks,
WD

 

[Kestrell]

http://www.atomicaquatics.com

Click on "Split Fins". There is a good explanation of how these type of fins work.

 

[Charlie99]

Kestrell, I'm pretty sure that Willydiver is asking about the older Jetfins, not the new twin jet split fins.

"Considered the standard for power and durability since 1965. " and "Proven vented design
Decreases drag on the upstroke; enhances thrust on the downstroke."

As to the question of how those fancy vented fins work ... they are just a gimmick. They'll never last. One should use big flat board fins. (sound vaguely like what many now say about splits????)

 

[edwinh]

They don't.

 

[kazinvan]

Split fins don't work??? Mine seem to work just fine. I get the same power that my dive buddies do andI have less fatigue than I did before I used split fins (Oceanic V12's).

 

[Nemrod]

They don't work, it is all show and no go. Simply a styling exercise like tail fins and fake hood scoops on cars. In fact, they may well detract from performance. N

 

[raposarose]

This thread is not about split fins.

 

[freediver]

The idea behind vents, ribs, channels, etc..is to "channel" the water behind you so this will translate into forward and efficient propulsion. With no channeling ability, the fin will tend to "sideslip" upon engaging the water, thereby losing its forward thrust.

 

[Allison Finch]

Nemrod, you, obviously, know nothing about split fins.

Willydiver,
The SP jet fin vents work by eliminating the turbulance caused by the fin on the downstroke. You kick the fin down....water is forced through the vents which are angled just right to have the current push toward the tip of the fin....as water goes over the tip edge of the fin, it creates a pocket of turbulance behind the blade....turbulance=drag.... the current forced through the vents is strong enough to push this turbulance pocket beyond the edge of the fin.....the drag no longer "pulls" or effects the fin....you don't expend energy fighting this drag.
US Divers copied the jets with their Rocket fins. Unfortunately, SP patented the angle of the vents and USD could not use the same angle. Their vents pushed water at an angle that provided little benefit, hence a much less efficient design.

Does that answer your question??
WHEW!! I hope so....

 

[Nemrod]

Allison, obviously you do not realize ---A) we not talking about split fins and B) Jetfins are not split fins and C) you have no proof that fins exactly like the Jetfins minus the vents would not in fact work better so then D) I say baloney macaronni. N