blade stifness at depth?

[Ascendv6]

I have read that blade stiffness changes at depth, or perhaps, I have misunderstood what is being said. I am diving with Picasso Team Black fins now. I feel like they are really sloppy, from the surface to the bottom(37 feet deepest dive to date). I am not sure how fins can become more mushy, soft, flexible, sloppy at depths.
I am not asking for fin suggestions. I would just like to understand the dynamics involved. I have read through numerous other posts(search function), but they do not address my specific question.

Why do fins become sloppy at depths?

Thank you for your help.

Darren

[ryddragyn]

The thermoplastic fins properties change with temperature, so maybe they would actually get stiffer (slightly) at a really sharp, cold thermocline. But I really doubt it would be noticeable.

I think the depth/sloppiness issue is more to do with the greater water pressure you're fighting against at depth, and associated wetsuit compression, etc. Plus there are the psychological effects of diver fatigue and that sense of urgency to get to the surface. No such thing as soon enough when you REALLY need to take a breath.

Try a fin with side rails for water channeling and see if you detect the same "floppiness" with the non-railed Picassos. I experienced the same sensation with non-railed fins before (Esclapez). After switching to railed fiberglasses, I found the biggest difference to be rebound/elasticity.

Just my $0.02.

[cww180]

Originally Posted by Ascendv6

I have read that blade stiffness changes at depth, or perhaps, I have misunderstood what is being said. I am diving with Picasso Team Black fins now. I feel like they are really sloppy, from the surface to the bottom(37 feet deepest dive to date). I am not sure how fins can become more mushy, soft, flexible, sloppy at depths.
I am not asking for fin suggestions. I would just like to understand the dynamics involved. I have read through numerous other posts(search function), but they do not address my specific question.

Why do fins become sloppy at depths?

Thank you for your help.

Darren

If you feel like the Black Team blades are sloppy even on the surface then your are a beast! I thought they felt like 2 pieces of plywood.

[5869]

Originally Posted by Ascendv6

I have read that blade stiffness changes at depth, or perhaps, I have misunderstood what is being said. I am diving with Picasso Team Black fins now. I feel like they are really sloppy, from the surface to the bottom(37 feet deepest dive to date). I am not sure how fins can become more mushy, soft, flexible, sloppy at depths.
I am not asking for fin suggestions. I would just like to understand the dynamics involved. I have read through numerous other posts(search function), but they do not address my specific question.

Why do fins become sloppy at depths?

Thank you for your help.

Darren

Great question. I'd like to know the technical explanation for this if there is one. The only thing I can come up with would be that your booties could compress thereby allowing the energy to escape transmission from your foot to your fin. This of course is not the same as the fin itself becoming sloppy.

Originally Posted by ryddragyn

The thermoplastic fins properties change with temperature, so maybe they would actually get stiffer (slightly) at a really sharp, cold thermocline. But I really doubt it would be noticeable.

I think the depth/sloppiness issue is more to do with the greater water pressure you're fighting against at depth, and associated wetsuit compression, etc. Plus there are the psychological effects of diver fatigue and that sense of urgency to get to the surface. No such thing as soon enough when you REALLY need to take a breath.

Just my $0.02.

Alex: First off, Welcome to Spearboard.
Secondly, I thought about the temperature thing but this seems like it would make things work inverse to whats being proposed. I think cold water is generally deeper and would make the fins stiffer and as you suggested I would suspect that the change in temp is likely too brief and too minor. I don't understand the dynamics of water pressure enough so you may have it there.

[patrick]

well, i have not been too terribly deep, only to 100'. but i did notice it is a lot harder to get moving down there. but i was also about 12# negative by the time i got down there. fighting all that weight going up i think is what you mainly feel. i dont have any problems swimming laterally at depth, but trying to push my festively plump self back up to the breathin' air is a lot harder than when im in shallow...

as far as the black teams, i felt the same way in them, but mainly because the darn heel of the footpocket is so wide. and plastic blades are not the most responsive anyways...

[Adelito]

plastic fins tend to soften with time, especially in the heat/sun. I know I have a pair of black teams.thats why carbon blades are better, they offer a consistent amount of resistance, and they respond by opposing the force you put on them(why they snap back). rails allow the water to flow the length of the fin, reducing the weak point, which is roughly where the pocket rail ends. one thing to consider in the fit of the pocket, I know in Cali your socks may range from 5mm-2mm, a change in thickness of the sock may create loss off power. also the footpocket stiffness- h.dessault - hard, omer-med/hard.Spetton - med/soft. Picasso - soft.

hope this helps

[Ascendv6]

Well, thank you for the info. I just now purchased a pair of Spetton Fiber Glass 2's from Neptonics.

Hopefully next weekend the conditions will as good as they were today! Maybe someone is running out to do some paddy hopping or maybe down to the 'Nados and maybe they would like a paying anchor ho with new fins onboard?

Darren