Diving Performance - Beyond Drag (article Series And Discussion)

[fjpatrum]

I did, but it was a while ago, back before I started designing Revision 1. Seeing as how my goal was to attempt to make the scuba kit a hydrodynamic ghost (i.e. - get as close to the drag of a freediver as possible), I don't see how comparing against the freediver baseline is being disingenuous.

Because you're trying to make people believe there's a big difference between existing scuba equipment and the designs you've come up with but you're showing a difference between scuba and freediving. In the videos I see a half-knot difference between your first gen scuba setup and a free diver. I, as an engineer, see that as not a valid comparison because it doesn't show any improvement to me over the existing scuba configuration. I.e., what I use. I'm not a free diver; I don't expect (or want) free-diver performance. You show me a half-knot difference between your kit and mine and you'll officially have my attention. Do you not see the difference?

If you want to get people interested, you have to market (even if you're just marketing ideas) to what they care about. Freedivers don't give a damn about scuba efficiency. Similarly, scuba divers, for the most part, don't care about being as fast as a freediver. You market your product (in this case information) to your demographic.

This is not a marketing video. This video is a record of my testing, and just the very first in-water test at that. I had not worked out any bugs at that point. Not that it was totally bad, but I did need to make modifications to the harness design to get the tank to sit in the proper position on my back. No doubt, the misalignment had a small impact, but probably not anything significant or that is likely to show a difference in kick counts. If you want to know how much drag a scuba kit has, why take my word for it? Strap on your kit and count kicks over a set distance. Then do the same without, and see for yourself. I get the feeling you don't really trust me anyway.

I thought it was a fine test and at least answers some of the questions you got in the other threads about your "test setup" and "test methods".

That said, the whole paper is a "marketing video". The product may be the information, but it's still a product. Hell, at the end you ask people interested in financially supporting the actual product contact you for more details. There's nothing wrong with that, but you can't have a statement like that and then say this isn't for marketing purposes. The whole thing is written as a white paper, which purpose is entirely to secure funding for something. Sure, that particular video isn't a "marketing video" but it's imbedded within something designed to be a marketing "campaign", of sorts.

I trust you just fine, I just disagree with you about the "need" for such improvements, and I see this as a business proposal more than an information piece. I find what you're doing incredibly interesting just for the "think about it" factor, if nothing else. But you have to convince people like me (an actual person who thinks change is good--not just a naysayer) to be on your side before you convince people that think you're full of hot air. I'm the fence sitter, the "independent" you want to court so you can get the critical mass to affect change.

Please, keep in mind this is not a product. I'm not trying to sell you anything here except information and ideas, and the only thing I am charging you is a little of your time to try to get the point across. If a lot of people get really excited about this project, I can come back to it and not leave everyone just hanging. However, now that the article has been published, I'm expecting to be done with this project. I have already moved on to my next project. The article is the terminus (except that I will personally continue to use my new experimental kit when I scuba dive).

I built all of this prototype equipment using moldless construction techniques. I have no production capability unless I go back to the beginning and build molds for production.

If you want people to believe your efforts are purely informational, though, you have to give them something that relates to their interests, not just yours, and you have to write the articles as informative, not as marketing. I suspect you have a lot more experience writing the latter, rather than the former, being a businessman. There's nothing wrong with that, I'm just pointing it out to you.

I like the look of the 2nd??? gen unit that had the black end caps. It looks like a more polished design and I suspect you probably could sell some if you were interested. I don't think it would get enough foothold to make it worth your effort to go back and build a production mold though.

Like I said, thanks for sharing the whole thing. It really is quite interesting and I hope to see more of your projects in the future.

 

[fjpatrum]

For production, it would either need an access panel, or extend the valve out through the side of the fairing. The fairing cannot not fill with air and drag you to the surface if that is your concern. A malfunctioning BC can do that, but a malfunction with this cannot.

Wouldn't extending the valve out of the fairing negate the point of the fairing?

I'm curious why you think this can't fill with air. What about it makes it not able to fill with air? Or do you mean it just doesn't have enough empty space to put enough air in to "carry me away"?

 

[REVAN]

I don't think it can hold enough air to displace more than a pound of water. There are a lot of places for this air to leak out. If you are anywhere near vertical (like you would be in an emergency ascent), It can't really hold any air.

Wouldn't extending the valve out of the fairing negate the point of the fairing?

A little. The most refined solution would be a spring loaded access panel.

 

[ronscuba]

Another SB member named Erik did some experiments and found diving without a wing made a bigger difference than the tank. He theorized the water channeled around the tank causing minimal drag, but a wing was a different story.

I would be interested in speed tests comparing uninflated, partially inflated, fully inflated wing. You mentioned you have your wing bungied to your Transpac plate. Curious to see how much difference the bungie makes. Maybe also compare an 18 lb wing vs. a 30 lb.

I think this is the kind of test that would interest scuba divers. I also think divers that regularly do drift or current dives, are definitely interested in going faster and being more efficient. Maybe not fanatical about it, but interested enough to change fins and modify gear configuration. In my experiences, it is a topic divers on the boat are discussing.

 

[REVAN]

Hell, at the end you ask people interested in financially supporting the actual product contact you for more details. There's nothing wrong with that, but you can't have a statement like that and then say this isn't for marketing purposes. The whole thing is written as a white paper, which purpose is entirely to secure funding for something.

It makes sense to leave the door open if I find a lot of people want in. There is not much reason for me to take the time to write the article if I am unwilling to get the technology out. But to me, this project is just a stepping stone. However, if folks like it, I could develop it further. I would just assume have someone else make and mass produce it. Going into production is a lot of work and I don't like selling diving gear. I'm an engineer, not a sales and marketing man. I'd rather go on to make the next cool thing than spend the next 5 years manufacturing and selling these.

 

[REVAN]

In the videos I see a half-knot difference between your first gen scuba setup and a free diver. I, as an engineer, see that as not a valid comparison because it doesn't show any improvement to me over the existing scuba configuration. I.e., what I use.

BTW: I measured a 0.1 knot difference, not a 0.5 knot difference. That was made pretty clear in the video. That's a difference on only 5% for adding scuba equipment that is about 20% the size of the diver. Pretty good I think.
You are amplifying the amount of the slowing effect of the scuba kit by 500%. I think doing that is being disingenuous.

 

[fjpatrum]

BTW: I measured a 0.1 knot difference, not a 0.5 knot difference. That was made pretty clear in the video. That's a difference on only 5% for adding scuba equipment that is about 20% the size of the diver. Pretty good I think.
You are amplifying the amount of the slowing effect of the scuba kit by 500%. I think doing that is being disingenuous.

Not disingenuous. An honest mistake going from memory while I was typing at work and not able to view the video. I still stand behind my point- show me a comparison of the difference between your scuba rig and mine if you want me to believe it will matter at all. At 0.1 knot difference between a free diver and your rig I don't see it likely to be any kind of factor at all. Especially when I don't know the difference between a free diver and a scuba kit without your rig.

 

[Monofin]

@REVAN Watching your test videos in part 3 I have some questions.

First, did you do any "baseline speed tests" with the scuba gear and no fairing? A baseline test of freediving versus scuba with the fairing doesn't make much sense if you're trying to convince people you're making a big improvement over existing scuba configurations. It also smacks of the disingenuousness I spoke of before. You're not comparing apples to apples and most people see through those kinds of arguments relatively quickly.
........

Now that all four parts are available, I would like to condense and share some thoughts.

From Part 1 under Normalization of Deviance “Today we can expect a strong diver with a typical recreational scuba kit to be able to maintain 1 knot and sprint at about 1.5 knots. This is a long way from my recommended minimum performance requirements of 3 knots sustained and 5 knots sprint.”

From Part 3 under Achieved Performance “In pool testing, I was able to cruise efficiently at sustainable speeds of about 2 knots. That is double the speeds that are typically sustainable for recreational scuba diving.”

The way I read the above is that this preliminary attempt achieved an improvement from 1 knot to 2 knots and is twice the half knot improvement that fjpatrum stated in post 51 would be needed to get his attention. I question the additional comment in post 51 about free diving being half a knot faster than the improved scuba. The video of part 3 shows free diving speeds of 2.0 knots (up to 2.3 knots only by streamlining with arms overhead) and scuba speeds of 1.5 to 2.5 knots depending on the kick cadence of the swimmer. I assume fjpatrum is using the low speeds in each case for his comparison. However, the cadence for 2 knot freediving and 1.5 knot scuba is not specified as being equal, nor does it look be equal. The 1.5 knot case looks like a very slow and relaxed swim by comparison.

As I see it, the speed for freediving without taking on a streamline arms overhead was consistent at 2 knots. The same kick cadence with the scuba kit produced 1.9 knots. Adding one extra kick per 20m distance got right back to 2 knots. In my view, that extra kick could have as much to do with accelerating the additional mass of the scuba equipment as it does with overcoming extra drag.

Part 1 made the general assumption that the typical scuba diver could maintain an average speed of 1 knot and a top speed of 1.5 knots. Obviously these are crude numbers as diving equipment and individuals have many variables. Your numbers may vary. But the assumptions made here are in very good agreement with this source: PowerSwim - Wikipedia, the free encyclopedia. Translating the speeds from the Aqueon paragraph reveals the referenced tests produced 1.85 knots over 1500 yards with the Aqueon and the fastest speed achieved by the same diver with fins over the same swimming course was 1.0 knots.

In part 1 revan states “As an engineer, I would recommend that any system we design to operate independently in the open ocean needs to be able to cruise at sustained speeds of at least 3 knots and be capable of non-sustained periods of speeds at 5 or more knots. Some people may want argue about these particular values for a diver speed requirement. Some will say this is faster than needed, that they have dived for many years with much lower capability. Others may say this has too little margin and the required swimming speeds need to be higher. ” Now that all the sections are available it may be appropriate to discuss these requirements, particularly since it has been shown that those numbers are not achievable with any state of the art equipment presently available.

From post 37 “I … ask fjpatrum why he bothers with fins at all when scuba diving. Many free divers dive without fins. The fact that he and virtually all other scuba divers use diving fins should make it obvious that propulsion and propulsive efficiency is important.” That question has not been answered by fjpatrum or any others that comment how speed when diving with scuba equipment is not an issue.

There are really several questions that should be answered. How fast do you go? How fast can you go? How fast would you like to go? How fast can you go with the effort you are willing and able to exert? Would you like to go faster with less effort? Would you like to go the same speed with less effort? Would you like to go faster with the same effort?

The answers to all of these relative questions are easy. (That is the questions that have a yes or no answer as opposed to those that require a numeric value answer.) The obvious answer is a resounding Yes! Would anyone want to argue that? Revan has shown how we can do this. That does not indicate that we should do it as there may be other penalities. That subject is open for discussion.

The answers to the numeric questions are more difficult, especially the part about effort. It is very difficult and subjective to measure effort. It is relatively easy to measure speed. Therefore, much of the emphasis of this article has to do with speed metrics when effort or efficiency is perhaps the real goal. Many of the negative comments have to do with a lack of a “need for speed”. That's debatable; but does anybody really think there is a lack of a need for efficiency.

There is not an investigation of how much of the performance increase comes from the fins revan has made versus how much comes from the scuba kit. However, the overall results of the equipment combination are impressive.

For now I would just like to say that I think revan has demonstrated a worthy achievement and if the above is correct fjpatrum may agree even though in post 45 he lists seven other tasks that need to be addressed. It looks like there is much more work to be done. The remaining question is will anyone take on this job, and if so who?

I'm an engineer, not a sales and marketing man. I'd rather go on to make the next cool thing than spend the next 5 years manufacturing and selling these.

It sounds to me like revan is not intending to continue development but is offering the technology if someone else is willing to carry the ball or at least offer encouragement. This forum has the ability to steer the direction this technology will take.

 

[REVAN]

In part 1 revan states “As an engineer, I would recommend that any system we design to operate independently in the open ocean needs to be able to cruise at sustained speeds of at least 3 knots and be capable of non-sustained periods of speeds at 5 or more knots. Some people may want argue about these particular values for a diver speed requirement. Some will say this is faster than needed, that they have dived for many years with much lower capability. Others may say this has too little margin and the required swimming speeds need to be higher. ” Now that all the sections are available it may be appropriate to discuss these requirements, particularly since it has been shown that those numbers are not achievable with any state of the art equipment presently available.

I'd like to point out that even at these speeds that I have recommended, a diver would still be slower than just about all other nektons in the ocean. Sea turtles usually lumber about fairly slowly, but when they want to move, even they are pretty quick. According to Sea World, loggerhead sea turtles have been recorded swimming at 5 knots. That may or may not be an actual sprint speed.

The bottom line is, I think my numbers are reasonable and not excessive when comparing to what nature deems necessary for mobility in the ocean. I think a turtle is a fair analog to use for a diver, and I'm proposing that we copy their mobility specifications. Do you want to act like you belong in the ocean, or act like a tourist?

https://seaworld.org/en/animal-info/animal-infobooks/sea-turtles/adaptations

 

[wetb4igetinthewater]

Do you want to act like you belong in the ocean, or act like a tourist?

Now, now, that's not being very nice.

OP, you certainly have some interesting ideas, something that I'd like to experiment with WHEN I want to dive THAT way.

But most of the time, I want a super slow dive, filming or taking pictures of something where I stay in one area for possibly up to half an hour. Reducing drag won't help me much. If you have a camera with a full frame sensor, you are not going to be traveling all that fast. Nor would you want to typically. You want to slow down and smell the roses.

People dive in very different ways for different reasons. Some are definitely on board. Some, like myself, are curious. And some have no interest in what you are doing at all. That doesn't mean they act like tourists. They can be one with the ocean as well, soaking it all in as they drift slowly along.