What are the most buoyant fins

[wetb4igetinthewater]

Hi,

I have heavy legs and after just doing a peak buoyancy course the instructor says I need the most buoyant fins I can find (may still have to change weight position but thats for another day), I have found some old threads but wondered if there are any new fins that are more buoyant.
Is there a buoyancy rating for fins?
If I email manufacturers will they have a better idea?
I am starting to learn frog kick so ideally I want them to be good for that as well.

I am advanced open water and rarely go below 30m if that makes any difference

Thanks

What is your exposure protection? Full length 3 mil? Do I understand that correctly?

How much weight do you use also? Trim pockets on the upper cylinder strap can help. Get rid of your cheap BCD. Consider a BP/w.

It really is about weight distribution. You will only find slightly positive fins, like the Deep 6 Eddy fins and a few others.

 

[Robert H. Diver]

I would seriously question the knowledge of your instructor... That doesn't exist a diver which needs some extra buoyancy in the legs...

In scuba you need to shift your weight down as much as you physically can. Becomes even more critical in drysuit.

Anyway to explain it simply, the reason you are angled backward and have your legs low (part of it is posture) is that your weight is too high. And it's very easy to prove it to you: try to get flat if you raise your legs and try to be flat, you will have a sensation that you flip forward. So the natural reaction is to stay backward.
It's counter intuitive but try to picture a pencil in balance. If it's stable not flat it means there's too much weight on the high side.

Look up
Contract your glutes
Shift your weight down

And change your instructor

@boat sju CC

Why would you want to shift weight back down towards his legs instead of towards his head on some cam band trim pouches? That doesn’t make any sense.

 

[FishWatcher747]

Anyway to explain it simply

Please explain it not simply.

 

[TheScubaPanda]

What?

Let me try to illustrate.
If you are stable and not flat/horizontal. The side "under" is the lighter side. If you were to force it horizontal. The pen would flip on the heavy side (green).
The same happen to you under water. Force yourself underwater to be flat for one sec, you will feel yourself flipping head down.

 

[TheScubaPanda]

Let me try to illustrate.
If you are stable and not flat/horizontal. The side "under" is the lighter side. If you were to force it horizontal. The pen would flip on the heavy side (green).
The same happen to you under water. Force yourself underwater to be flat for one sec, you will feel yourself flipping head down.

View attachment 710861

Don't get me wrong part of the job to reduce your angle is : head up and body tension and body posture.

But there is no chance you manage with more weight on your head. The more you add equipment to your upper body : twinset, stages, etc. Or buoyancy close to your feet (aka. Drysuit), the more shifting your weight down becomes critical.

I don't want you to believe me / trust me blindly : do the test. See for yourself.

1. Try to force yourself horizontal, you will feel you flip your head down.

2. Try to lower your weight, this will allow you to decrease the angle more before this feeling of "flipping forward" occurs.

It's the same for everybody. Unless you have a very very odd body shape. I've never encountered a single diver that needs more weight on his shoulders or extreme buoyant fins.

In wetsuit you need fins "not too much negative". That would create too much of a weight lever: no jet fins.
But there is a whole range of fins neutral or lightly negative that you can use from recreational to tec oriented (Apeks RK3 non HD for example)

 

[rongoodman]

It’s pretty obvious with doubles, which is why tail weights can be helpful.

 

[boat sju]

Let me try to illustrate.
If you are stable and not flat/horizontal. The side "under" is the lighter side. If you were to force it horizontal. The pen would flip on the heavy side (green).
The same happen to you under water. Force yourself underwater to be flat for one sec, you will feel yourself flipping head down.

View attachment 710861

If the pink is your head, the fulcrum of the pencil is your hips, and the dark end represents your feet, add weight to the pink tip and what happens?

 

[rongoodman]

In his illustration the dark(heavy)end is your head. The only way to keep from flipping forward is to shorten the lever arm, AKA, assume more of an upright posture. Adding more weight there is only going to force you more upright.

 

[TheScubaPanda]

If the pink is your head, the fulcrum of the pencil is your hips, and the dark end represents your feet, add weight to the pink tip and what happens?

In his illustration the dark end is your head. The only way to keep from flipping forward is to shorten the lever arm, AKA, assume more of an upright posture.

Correct, diver's head is dark green. I've never seen a diver with feet in the air STABLE.
Don't forget that to draw any conclusion you must be stable (meaning you can hold the position for 20min, without your feet & head moving up or down, and it doesn't require a significant effort to do so) => In short: it's your natural resting position.

If everytime your feet keep going up => you're not stable => you're flipping forward => too heavy on your head.

It's counter intuitive "my feet are down low, I need more weight on my feet". Though if you think a little bit of the physics behind it or the pencil in equilibrium proxy you can get a very good understanding of why.

And again, please please don't trust me. Try for yourself.
The first time a competent instructor told me "John your weights are way too high", I absolutely reacted "whaaaat? but my feet are already way too heavy, that makes no sense". Long story short I was horribly wrong and I understand why now

 

[TheScubaPanda]

If the pink is your head, the fulcrum of the pencil is your hips, and the dark end represents your feet, add weight to the pink tip and what happens?

If for whatever reason you ended up with your head low stable, aka your head is the pink side of the pencil.

1. I'm seriously intrigued by your body shape / equipment, I've never seen this in my life. Would you mind giving some details ?

2. Same logic => you need to add weight to your upper body part. That would be the correct move.

But again, I have never ever seen a diver in this situation.