SP pro fin

[duckbill]

I am curious about your fins (and those linked by David) as the holes are above the vents and not below as mine are. Seems like quite a design change. Plus yours have all those patents for various countries. I was told that the lightnings were a later model (newer) so I wonder if, in fact, yours are older than previously suspected. Or maybe that was a change specific to the pro models? Your toe pockets also look different (flat and boxy) when compared to mine.

Dale, did you notice his vents are completely opposite those of standard Jets? (flowing bottom to top, instead of top to bottom)

 

[DaleC]

Why yes I did! So are the ones in the photo David linked.
That is a major difference. The vents on mine (for lack of a better term) allow flow on the down kick (power stroke) while their's allows flow on the up kick (recovery stroke). I wonder what the rationale was?

 

[David Wilson]

Why yes I did! So are the ones in the photo David linked.
That is a major difference. The vents on mine (for lack of a better term) allow flow on the down kick (power stroke) while their's allows flow on the up kick (recovery stroke). I wonder what the rationale was?

The 1975 Swedish-language Scubapro catalogue at

www.sukellusmuseo.fi

I mentioned in an earlier message acknowledges the "channelling" difference between Jet fins and Pro fins. The caption reads: Pro-Fin är en modernisering av den äldre Jet-Fin. Kanalerna är nu "rätt vända" för att ge SLIPSTREAM-effekt, which translates as Pro-Fin is a modernisation of the older Jet Fin. The channels are now "turned round" to give the slipstream effect. So the reversal of the vent directions in the Pros seems to be all about "modernising" the original Jet Fin design, originally conceived by Beuchat of Marseilles, France, and generating the "slipstream effect". I'll leave it to the physicists to explain what the "slipstream effect" is all about.

 

[Luis H]

If I recall correctly, WhiteStag also had a very similar fin with the vents in the reverse direction as the standard Jet Fins. The vents shape looked just like the Pro-Jets. When I first saw the WhiteStag fins, we thought for sure they were like that just to by-pass the patent on the Jet.

I saw the WhiteStag fis before I ever saw the Scubapro Pro-Jets. Actually, now I even wonder if I only saw the WhiteStags or if they just look so similar that I am confusing them now.

 

[duckbill]

......... which translates as Pro-Fin is a modernisation of the older Jet Fin. The channels are now "turned round" to give the slipstream effect. So the reversal of the vent directions in the Pros seems to be all about "modernising" the original Jet Fin design

Ah, yes, modern water is different than when the Jets were first designed. LOL!

 

[DaleC]

I can only imagine this but... with the ordinary Jets the venting allows some of the water resistance to bleed off on the down stroke (generated mainly by the quadriceps). To me this would reduce some of the effort (stress) that pushing those big fins requires.
With the Pros, the venting allows some of the water resistance to bleed off on the up stroke (generated by the hamstrings) thus allowing faster recovery time for the next power stroke.
With the ordinary Jets the venting eases the effort of the quadriceps and with the Pros, the venting reduces the effort of the hamstrings. Perhaps a designer thought a professional diver who was in the water all day might need to rest his hams more than his quads (which are the bigger and more powerful muscle group).
Just a guess, but now I want a pair of those fins for my collection.