Why don't split fins work so well in current?

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

Joining is quick and easy. Log in or Register now!

On scubaboard the dogma is that you must frogkick and you must use paddle fins.

If you are in mid column with no reference you would have no idea if you were in current or not. Only until there is a fixed reference do you notice suddenly there is a current. If the current is traveling faster than your muscles and aerobic capability and the efficiency of the fins you have chosen can convert that input into forward thrust, then you will go backwards in relation to the fixed object. Simple.

All this ducking and covering and eddying and swirling and twirling, oh hum bug. If you are trying to make way straight into a current, it is you (the engine) and your fins. Some fins do better than others, it has been shown repeatedly that certain split fins are very fast and that others are not, sorta like some paddle fins essentially suck and others are superb. As well, some people do better than others, physical fitness trumps finology within reason.

A world champion cyclist could near a bout whup tail on a K Mart Schwinn against some noodle on a 5,000 dollars carbon machine, at some point, it is you, the underwater swimmer. If the engine ain't got no go, you ain't gonna go and you are the engine, not the fins.

Please note line three of my sig.

N
 
On scubaboard the dogma is that you must frogkick and you must use paddle fins.
I think you'll find more people who use splits here than paddle fins. But this is about getting the most out of your dive experience, so it's no wonder that the best techniques are talked about frequently.

All this ducking and covering and eddying and swirling and twirling, oh hum bug.
If all you can do is a flutter kick, then you simply can't duck low enough or behind objects to effectively escape currents. Why? Flutter kicking pushes water up, down and back. If you get too close to the reef or bottom, then all you'll do is silt the place up and this is doubly true if your trim puts you feet downward. On the other hand, a non-silting technique, such as a frog kick, combined with great trim allows you to swim within an inch of the bottom keeping out of the main current. It's obvious to many who use these techniques that if this is "hum bug" to you, then you're simply doing it wrong. Yeah, I know that no one likes to hear this, but it's true. The world champion cyclist uses their world class technique just as much as their stamina to win the race. Don't swim harder: swim smarter. Don't fight the current, dodge it.

I wonder how many people begin their dive INTO the current. I asked this of the young lady I was guiding yesterday, and she really had no idea why this is important. It took her a bit, as she wasn't used to currents, but as soon as she got the idea that staying low meant easy diving, she quickly adapted and had a wonderful time. At the half way point of the first dive, I simply surfaced for a moment, took a bearing on the boat with my compass and made sure that I led the current. We were back under the boat in no time, so we finished the last few minutes of our dive exploring the reef directly under the boat. We did our safety stop on the mooring buoy line and then floated to the ladder. That 11 year old, handled the currents just fine with her generic paddle fins.

On the second dive, our awesome Captain (Troy from Horizon Divers), planted us on the stern of the Benwood which was down current of the wreck. Again, we kept low and patiently worked our way to the bow. The ride back was again pretty easy and we still ducked out of the current to slow our transit back. My diver noticed that many of the fish were way low on the lee side of the wreck. On the surface she asked why, and I related it back to what we were doing: escaping the current. Heck, even fish see the benefit of ducking, covering and finding eddies. Maybe divers should learn a bit from our fishy friends?
 
On scubaboard the dogma is that you must frogkick and you must use paddle fins.

If you are in mid column with no reference you would have no idea if you were in current or not. Only until there is a fixed reference do you notice suddenly there is a current. If the current is traveling faster than your muscles and aerobic capability and the efficiency of the fins you have chosen can convert that input into forward thrust, then you will go backwards in relation to the fixed object. Simple.

All this ducking and covering and eddying and swirling and twirling, oh hum bug. If you are trying to make way straight into a current, it is you (the engine) and your fins. Some fins do better than others, it has been shown repeatedly that certain split fins are very fast and that others are not, sorta like some paddle fins essentially suck and others are superb. As well, some people do better than others, physical fitness trumps finology within reason.

A world champion cyclist could near a bout whup tail on a K Mart Schwinn against some noodle on a 5,000 dollars carbon machine, at some point, it is you, the underwater swimmer. If the engine ain't got no go, you ain't gonna go and you are the engine, not the fins.

Please note line three of my sig.

N

Sure you are right that there are divers that won't be able to push fins that other divers could easily push, and this is one reason currents are non-issues for some, and not for others....
But there is a large group that could have a much easier large current dive experience....this group needs to read and use bottom structure, and this group will benefit from using the right fins for currents.

In Palm Beach, where you know we do have good strong currents on some days, the boats that typically run to the sites with the highest currents ( also tend to cater to the more advanced divers), tend to have divemeaster and dive guides wearing freedive fins..... On diveboat Narcosis yesterday, there were at least 4 divemasters with freedive fins, and at least 7 divers with freedive fins, out of a trip of 26 divers. This skews the stats the dive industry would use to discuss right fins to use in larger currents.
 
A good way to think of it is to think of split fins being 1st gear on your 10 speed bike. It is easier to pedal, but you don't go as far with each cycle of the pedals.
This was pretty much what came to my mind.
 
.
But there is a large group that could have a much easier large current dive experience....this group needs to read and use bottom structure, and this group will benefit from using the right fins for currents.


Well, yeah, but you have to get to the bottom first.

N
 
Well, yeah, but you have to get to the bottom first.

N
Agreed. A good boat...any boat I would consider using( any Captain I would use), will provide an upcurrent drop....the captain needs to know the descent speeds of his divers, and estimate the distance upcurrent to drop the divers....When we reach bottom, it is a leasurely drift into the wreck or reef...If it is a wreck, once you are approaching, it becomes your job to know how and where to approach to use the currents to your advantage. With the right captain, even a 280 foot deep wreck in a 5 mph current is relatively easy to get into.

Lazy ass captains that choose to anchor in strong currents need to be avoided like split fins :)
 
Agreed. A good boat...any boat I would consider using( any Captain I would use), will provide an upcurrent drop....the captain needs to know the descent speeds of his divers, and estimate the distance upcurrent to drop the divers....When we reach bottom, it is a leasurely drift into the wreck or reef...If it is a wreck, once you are approaching, it becomes your job to know how and where to approach to use the currents to your advantage. With the right captain, even a 280 foot deep wreck in a 5 mph current is relatively easy to get into.

Lazy ass captains that choose to anchor in strong currents need to be avoided like split fins :)

:), not all high current dives are done on the drift. I know it is the general thing in WPB and SFla but drift diving is not the practice in many places. I have done many dives as I am sure you have as well where the boat is anchored over the site, Spiegal, Grove, Oriskany, Vandenberg, Flower Gardens Banks drops and many other places. The dive often requires a long swim/transit down an anchor rode which even set at a 4:1 scope, in 100 feet of water, that is a 400 foot swim, up current. Sure, once on the bottom or to the wreck one can use the structure to provide relief from the current as Net Doc suggests, good plan, as you make your dive up current to your turn point and then drift back. As well, I have encountered strong down currents in Coz, Caymans and a few other places.

:wink:, I think I had one of those lazy a** captains recently in WPB, I got blown off the line, my excuse, I do not trust my 4,000 plus dollar camera to my lanyard which limited my ability to hand over hand down the rode as the captain suggested.

But on topic I have used the Atomic Smoke fins as a try out a couple of years ago for several days. I found them at least as fast against current, in fact faster in my opinion, than my Jets for a given effort. They also frog kicked quite well but the Jet is still champ there. Yep, I need to get me some of those free diver fins to try out, will start studying on them.

N
 
All I can say is I have no problems with splits in high currents. I dive a lot in PNG and Indonesia in extreme current situations. I often keep up and pass people in paddle fins with a lot less effort. If you are having problems in current....look at you technique before blaming the fins.
Its all about stroke rate and frequency, you can get a stiff blade and waste energy doing short strokes or splits doing long strokes- in current short strokes win due to drag profile/streamline.................................opposite to what has been augmented in this thread the physics rule supreme!

---------- Post Merged at 04:12 PM ---------- Previous Post was at 03:58 PM ----------

Pendergast, DR; Mollendorf, J; Logue, C; Samimy, S (2003). "Evaluation of fins used in underwater swimming". Undersea Hyperbaric Medicine (Undersea and Hyperbaric Medical Society

This study showed that when the split fin designs were fused at the split, there was no degredation in efficiency, and will improve efficiency in some types of kicks. Divers with moderate to high levels of conditioning are better served using a stiffer, paddle style fin. Split fins will be easier for a poorly conditioned diver to kick, but will not be more efficient in current, and will need more kick cycles per unit of forwrd motion. A good way to think of it is to think of split fins being 1st gear on your 10 speed bike. It is easier to pedal, but you don't go as far with each cycle of the pedals.


Close but no cigar dude!
It's horses for courses and nobody here has given the full goods(typical amricons)...YET! intellectual property rights/benifit; I guess is holding this back(watch the nubs squirm), the failure of capitalism, with a repug that pays 14% on a "declared" 12million dollar year income(what a bunch of thieving mofo's they are at the top!).......
There is no multi-geared or length fin YET! THE AQUALUNG SLINGSHOT IS THE BEST ATTEMPT YET(like a chevy aquaglide 2spd autotranny!)- BUT it breaks!and isn't as good as splits or short rigid fins up current!
Hooooo Wahhhhhhhh'
Damo'
 
:), not all high current dives are done on the drift. I know it is the general thing in WPB and SFla but drift diving is not the practice in many places. I have done many dives as I am sure you have as well where the boat is anchored over the site, Spiegal, Grove, Oriskany, Vandenberg, Flower Gardens Banks drops and many other places. The dive often requires a long swim/transit down an anchor rode which even set at a 4:1 scope, in 100 feet of water, that is a 400 foot swim, up current. Sure, once on the bottom or to the wreck one can use the structure to provide relief from the current as Net Doc suggests, good plan, as you make your dive up current to your turn point and then drift back. As well, I have encountered strong down currents in Coz, Caymans and a few other places.
Nemrod, this is kind of what I am going for with this comment....Like you, I have dived in many places outside of Palm Beach with real currents. Whether here, or in places like Fiji, I have found there are "certain things" that don't change, like the immutable laws of physics....One of these, is that if you really have a big current, then the BEST way to do the dive is from a Drift Dive boat ( non-anchored). My assumption is that the habitual anchor operators that do this with strong current areas, do it so they can run multiple groups at the same time, with no attempt to match bottom times or descent rates. It takes far less crew, it takes far less captaining skill, and it allows one boat to put EVERYONE on a shipwreck with no thought to much by the captain.


In contrast, a Palm Beach operator will need to make sure that all going down on a wreck dive on a day with a big current, descend at roughly the "normal" descent rate for divers....they need to know if there are any slow descenders( with ear issues), and if so, create a separate drop for them with a much longer lead upcurrent. Also, the captain needs to create some form of bottom time plan, IF there are any divers in the group that are using rebreathers or doubles, who might otherwise stay down 2 or more times as long as all other divers....meaning pickup will be affected by where these guys will drift to with long floating deco....this also involves their having their own float they can hook off, and then unhook and float with while doing deco.

None of this planning is hard, but it has to be done. The upcurrent dropping though, is a great skill--one where huge differences can exist between captains. One of the most amazing in Palm Beach is Lynn Simmons, captain of Splashdown...She got the reputation in the mid nineties, of having a near magical ability to drop any diver exactly on anything. She could estimate each divers descent speed, and figure top current, mid currents, and bottom currents, and know when to drop divers to get them right where they would want to be....Even before GPS, I remember Lynne telling me once when we were 2 miles from shore...."Dan, when I tell you to dive, jump in annd swim straght down fast, when you hit bottom look stright to the left( south), and you will see a cave with a huge jewfish....this was 90 feet deep, with a 2 mph current...And I did look left and see the Jewfish in the cave :)


Lynne was also famous for tech drops. One of the hardest was/is the Skycliffe...While only 225 feet deep, it gets more gulfstream intrusion than the deeper wrecks, and far more eddy effects....Lynne would ask George Irvine, Bill Mee and myself, where on the ship we would like to land...she knew exactly how fast we would descend, and could drop us right on a wheelhouse if that is what we wanted. All of us found this amazing.
Since all the boats in Palm Beach do these current drops every day, all good captains stay...all bad captains are short lived....bad ones will need to move to still water dive location areas.

I see this boat and captain selection issue just like I see "gear selection" and buddy selection for a dive.

When Sandra and I dove in Fiji in big currents, I could not get them to learn drift diving boat operation just for me...so we adjusted our diving accordingly....it was incredibly fun diving, and certainly not taxing for either Sandra or me to anchor dive in the large currents--but we knew there was a much better way that the dives could be run. If we "moved there", we would work with a boat untill they drifted these sites the way they should.

In the Keys or other areas, choosing the boats SHOULD BE a big issue in how you handle currents in a smart way. The more currents bother you, the more you want a captain skilled in drift techniques. However, the better you are in high current diving, the more you will be pissed about a captain with the defective anchoring practices.
:wink:, I think I had one of those lazy a** captains recently in WPB, I got blown off the line, my excuse, I do not trust my 4,000 plus dollar camera to my lanyard which limited my ability to hand over hand down the rode as the captain suggested.
I know of no boats in Palm Beach that anchor without specific demands to do this by a group unwilling to do a drift....Please either tell me the name of this boat here, or PM it to me. I use all the major boats in Palm Beach, and am shocked to hear something like this....

But on topic I have used the Atomic Smoke fins as a try out a couple of years ago for several days. I found them at least as fast against current, in fact faster in my opinion, than my Jets for a given effort. They also frog kicked quite well but the Jet is still champ there. Yep, I need to get me some of those free diver fins to try out, will start studying on them.

N
I would not disagree at all...Jets are great at slow to medium flutter kick, and for all frog kicks, and great at reverse kicks, helicopters, etc. Jets get to be very inefficient at high speeds, even for an elite athlete they are the wrong tool for high speed flutter kicking. For this, in a scuba length fin, I have found Excellerating Force Fins to be the most efficient by a huge margin....For open water reef diving, where huge long blades will not interfere with a tight overhead penetration, then I like the carbin fiber hybrid , very long bladed DiveR freediving fins the most, though the excellerating Force fins are a close second even here. Unlike the DiveR's, the Excellerators can be used by a diver that is not an elite level athlete, as they utilize muscles everyone uses, and dont require as much brute strength as the big stiffer carbon fiber freedive fins will.
 

Back
Top Bottom