coldwaterlloyd
Contributor
Wow , way to go Arak .
Looks like we have a new "Bob Evans"
Keep it up man , LL
Looks like we have a new "Bob Evans"
Keep it up man , LL
My 'Pretty Fin' Patent
- Thread starter Arak Lea
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Not nessary, at the basic level of t
Yes, I built one set, and performed a kick-count test. I tested that against 8 other fins, including a Jet-Fin and a long fin.
Everyone's objections and noted challenges definitely were represented in the first fin.
Heavy? Check
Complex? Check
Excess load to the toes? Check
Likely expensive? Check
But...on the other hand...
Work at all? Check
Performed well? Conditional Check
Can the design be improved for all the issues noted above? Yes.
Expensive to do so? Double-Check
Worth the effort? Mostly likely still Check.
Frankly, the objection about cost is dumb. Scuba is all about high-end sports equipment, a cheap price is not the norm.
The 'Long Fins' niche I tested with, those are typically $250 to $350 fins.
If these fins are better in some way, someone will buy them, no problem. Higher the cost, the fewer will do so, generally.
The kick count test was a 40ft pool, how many kicks to go up and back. The prototype fins counted at 38, and 43.
Another prototype from a friend, John Ratliff (vintage scuba forum), these were 43, the other 7 ranged from 43 to 60.
But my prototype, it became very obvious that the loading was painful, if not harmful, and need to be from half to as much as 10 times less stiff. This would both move the loading closer to the foot, reduce the actual load and be more efficient as well.
I do not mind everyone's critique and objections. You want all that up front. These are the things to address that will make you succeed should you solve them. SO I thank you all for the input. Whom ever follows up on the concept (likely not me, unless I were hired for the purpose, hint hint) thanks you too.
Here is the first build ...
Ahh, Ratliff's scoop fin?
I've never understood the value of kick count tests. Your prototype looks relatively long and stiff. Longer and stiffer will move a lot of water regardless of any shape advantages, but at the expense of discomfort and difficulty in control, which appears to be what you experienced.
What you really want to know in a basic test is expended energy per given distance. The easiest way to approximate this is with speed runs, both at a diver's perceived moderate effort and max effort. The idea is that you'll have a somewhat consistent wattage either way, with the time telling you relative efficiency. The quickest way to know if your hypothesis has merit would be to run these tests swapping out the variable kicking surface on your prototype for a fixed surface with the same area and shape as your prototype when unloaded. And perhaps a fixed surface with the same area but the shape optimized for the downstroke.
I've never understood the value of kick count tests. Your prototype looks relatively long and stiff. Longer and stiffer will move a lot of water regardless of any shape advantages, but at the expense of discomfort and difficulty in control, which appears to be what you experienced.
What you really want to know in a basic test is expended energy per given distance. The easiest way to approximate this is with speed runs, both at a diver's perceived moderate effort and max effort. The idea is that you'll have a somewhat consistent wattage either way, with the time telling you relative efficiency. The quickest way to know if your hypothesis has merit would be to run these tests swapping out the variable kicking surface on your prototype for a fixed surface with the same area and shape as your prototype when unloaded. And perhaps a fixed surface with the same area but the shape optimized for the downstroke.
I guess I should make a few more comments.
Simulation and wind tunnel testing?
You are right that this fin has so many variables, such things are likely to come into to play, if there is any advantage to such improvements. But at this turn in the development, it's too basic. The concept needs to work at a base level, then the concept can be honed to perfection.
I have done some actual automotive wind-tunnel work in the past, and you can investigate lot before doing that work.
Fin specialization:
In this case a marathon use fin may require a lot of difference to a sprint fin. For my self I used a very different fin for water-polo vs scuba vs snorkel diving. In some cases you want a general fin that can do everything poorly but OK, and otherwise maybe a specialized fin that does one thing very well. Most fins are of the general nature. (most fins could use some flow-tunnel testing)
These fins are probably in the special category, but they also might provide the opportunity to be widely adjustable.
Those farallon fins I modified. Unmodified, they actually forced a person to bicycle in their kick, speaking of which, I hate that kick. It's inefficient for moving any distance. It mostly makes you feel like you are doing something, but aren't. But after my mod, bicycling was not easy to do.
SO about inefficientcy. You need to take seriously the difference between an aircraft wing that is stalled and one that is laminar (un-stalled)
The stalled one will drop a plane out of the sky unless to has double the power, practically at VTOL levels.
Normal fins are operating in a stalled condition normally. My intent is to operate fins in full laminar flow.
So yes, it's possible they may double the performance. (but with the foot still in the picture, maybe 1.25% ??)
That may mean that a half-sized 'Pretty Fin' will perform like a full sized regular fin. This would fix all the issues of loading and weight, maybe even cost. (but not complexity).
I will also note, there were 7 'Embodyments' in the patent. I chose to make one of the more complex ones.
I had to add this: Yes I don't like the kick test over something with power and loading metrics and control. But the kick test only requires a pool and fins to compare against. It only served to indicate if the concept is worth the next step.
Not for my budget, but maybe for someone else's. Should I have kept it secret?
Simulation and wind tunnel testing?
You are right that this fin has so many variables, such things are likely to come into to play, if there is any advantage to such improvements. But at this turn in the development, it's too basic. The concept needs to work at a base level, then the concept can be honed to perfection.
I have done some actual automotive wind-tunnel work in the past, and you can investigate lot before doing that work.
Fin specialization:
In this case a marathon use fin may require a lot of difference to a sprint fin. For my self I used a very different fin for water-polo vs scuba vs snorkel diving. In some cases you want a general fin that can do everything poorly but OK, and otherwise maybe a specialized fin that does one thing very well. Most fins are of the general nature. (most fins could use some flow-tunnel testing)
These fins are probably in the special category, but they also might provide the opportunity to be widely adjustable.
Those farallon fins I modified. Unmodified, they actually forced a person to bicycle in their kick, speaking of which, I hate that kick. It's inefficient for moving any distance. It mostly makes you feel like you are doing something, but aren't. But after my mod, bicycling was not easy to do.
SO about inefficientcy. You need to take seriously the difference between an aircraft wing that is stalled and one that is laminar (un-stalled)
The stalled one will drop a plane out of the sky unless to has double the power, practically at VTOL levels.
Normal fins are operating in a stalled condition normally. My intent is to operate fins in full laminar flow.
So yes, it's possible they may double the performance. (but with the foot still in the picture, maybe 1.25% ??)
That may mean that a half-sized 'Pretty Fin' will perform like a full sized regular fin. This would fix all the issues of loading and weight, maybe even cost. (but not complexity).
I will also note, there were 7 'Embodyments' in the patent. I chose to make one of the more complex ones.
I had to add this: Yes I don't like the kick test over something with power and loading metrics and control. But the kick test only requires a pool and fins to compare against. It only served to indicate if the concept is worth the next step.
Not for my budget, but maybe for someone else's. Should I have kept it secret?
This is the dumbest comment ever. We will call that comment #1. The rest was sensible enough.
In the past...
Comment #1 then comes, we don't need to swim, we have boats.
#1, followed by we don't need wheels we have feet.
#1 then we don't need fins, we have hands if you would only learn to use them.
#1, we don't need spoons, we have hands for that too.
#1, god never intended people to fly, where do you need to go where you can't ride a horse or float a boat?
#1, there is nothing in space useful to us, why go?
It is the go-to comment, until the thing exists and the usefulness becomes obvious.
Comment #1 would have us eating ants and bananas, if it had it's way.
When you look at the pressures around an air foil, most of the lift is in the front half, provided it is laminar flow.
The implication for fins, if that dynamic holds up, the loading center for the foil would be closer to the foot than the regular fin.
However, in my concept, the blade is held at a distance from the foot. If for the same power, the foil were smaller, then the location of the loading (the total average, or the center of pressure as it's called) will be again moved closer to the foot.
About the different positions in each kick cycle, the concept blade is sprung with elastic materials, as is the same for the regular fin.
The concept fin will exhibit a different profile in each point of the cycle, as does the regular fin.
I have not found a notable problem with that, but it is an area of possible improvement for both fin types, certainly more so for the concept fin.
PS, I am currently daring myself to show you the mono-fin concept and the water-tractor, and the octopus adaptation fin. Yes, all fairly half-baked, hence the dare is not working up to now.
Throwing technology at something is not a risk factor for me... it's a hobby
OK, what is wrong with existing fin designs that a new high-tech design will substantially improve without introducing new drawbacks or cost implications? What is the point of a design that makes finning 5% more efficient when the novices this is aimed at will still have poor technique and trim which would easily count for 50% more effort required than an experienced diver?
It's like bicycles; staggeringly efficient design that's "improved" by tinkering around the edges. A modern racing bicycle is just as difficult as a 50 year old racing bicycle to pedal up Alpe d'Huez. Agreed that the modern one will stop better!
The point being that there's some diving tech that needs innovation. There's a lot of diving tech that doesn't as it's reached the peak of development (masks, fins, snorkels, regulators, wet & dry suits, dive cylinders, etc.). Examples of recent dive tech innovation includes computers (praise be for Shearwater), rebreathers (now not sold with their own shovel), DPVs (much cheaper), dive lights (LEDs rock!), undersuits (modern fabrics), drygloves.
There's whole new areas that could well do with innovation such as underwater comms and direction finding, portable sonar (imagine using it to find the next piece of the wreck, automatic buoyancy devices (for novices), automatic weight checking, buddy locator...
Too early to judge, people. Who knows what benefits may come from the OP's efforts. May not be for scuba, may be for something else. Who knows? Let's not pee in his cornflakes.
I think you don't know where you are right now. This is not normal space where you are comparing the value of two or more existing options.
This is the high risk area of the unknown. (just this one thread) This is where you try to ferret out what is possible or not. Here you do not assume it is not possible. You assume it might be. And yes, often there is nothing of benefit found, hence the high risk.
If you don't like the risk, you shouldn't play. So the question for me is, why are you playing in this sand box, if you don't like the game?
We are not risking covid here. Just some intellectual energy. -mike drop-
For everyone else,
I greatly appreciate your encouragement. But honestly, I'm abandoning the idea here.
I'm simply putting it where an interested party can find it. And I'm answering any questions they need answered.
I do think it has merit, otherwise I would not post it here. I'm giving it up to unknown persons who want to take up the fight. Throw some technology at it!
It may well inspire some other ideas that do indeed change the world.
Similar threads
