Mike: Thank you for your input. That is a great read.
Split Fin Physics
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Mike: Thank you for your input. That is a great read.
Mike Boswell
Contributor
Mike: the USN, USAF, USMC and USCG use a variety of fins. Here are some comments from some military divers:
“I am a US Navy SEAL and have been in the military for 12 years. I use fins in many different applications such as jumping from helicopters, airplanes, long surface swims, and extensive combat diver operations. I have tested the Bio-Fin in all types of profiles and environments and have found it to be superior in all respects to any other fin I have used.
The tests have been surface swimming on side, stomach, and back; against current, with current, 90 degrees to current; navigation dives with open circuit and closed circuit, [and] deep dives with open circuit. Other applications have been static line parachute jumps, military free fall night water RAMS parachute jump, and closed circuit scuba exhaustion dive. The Bio-Fins did better in all applications in areas of speed, comfort, ease of swimming, gas consumption (V02 max), deep dives and heavy current. I used different personnel from the military Special Forces community; SEAL, PJ, CCT, SF, RANGER, to accomplish these tests.”
- Tim Core MM1(SEAL/SW) United States Navy
“I am a U.S. Army Ranger and have been in the military for 8 years. I have used numerous types and styles of fins in various applications and I have been impressed with the performance of the Bio-Fin. I have tested it in different types of profiles and environments and I strongly recommend the Bio-Fin to all swimmers and divers, civilian and military.”
- David A Bucknam SSG USA, U.S. Army Rangers
The Executive Officer of the Special Forces Underwater Operations School stated “I have been extremely pleased and impressed with the performance of the Bio-Fin. I have tested it in all types of profiles and environments and have found it to be superior in all respects to any other fin I have tried. Normally to obtain optimal performance I have to switch fin types depending on whether I’m diving or surface swimming. The Bio-Fins deliver superior propulsion in both profiles and in heavy current. Most importantly to the combat swimmer, increased efficiency means less gas consumption, giving the operator more subsurface infiltration/exfiltration time, and so increasing the chances for mission accomplishment.”
- Joseph Diekemper LT United States Navy
I well remember a call from a salty Master Chief after we had sent them a size run of our first shipment of bio-fins so they could evaluate the fins: "Well, I've got some good f-cking news for ya, and some bad f-cking news." I asked for the bad news first. The Master chief said he had taken the fins out of testing. The good news was "They work and until they all have them I can't have people trying to keep up with those who don't. These are SEALS, they won't quit until they cramp and can't move."
We are not the only fin used by our armed forces but we do sell quite a few to those who care not about brand name or marketing. They simply want what works for their mission.
“I am a US Navy SEAL and have been in the military for 12 years. I use fins in many different applications such as jumping from helicopters, airplanes, long surface swims, and extensive combat diver operations. I have tested the Bio-Fin in all types of profiles and environments and have found it to be superior in all respects to any other fin I have used.
The tests have been surface swimming on side, stomach, and back; against current, with current, 90 degrees to current; navigation dives with open circuit and closed circuit, [and] deep dives with open circuit. Other applications have been static line parachute jumps, military free fall night water RAMS parachute jump, and closed circuit scuba exhaustion dive. The Bio-Fins did better in all applications in areas of speed, comfort, ease of swimming, gas consumption (V02 max), deep dives and heavy current. I used different personnel from the military Special Forces community; SEAL, PJ, CCT, SF, RANGER, to accomplish these tests.”
- Tim Core MM1(SEAL/SW) United States Navy
“I am a U.S. Army Ranger and have been in the military for 8 years. I have used numerous types and styles of fins in various applications and I have been impressed with the performance of the Bio-Fin. I have tested it in different types of profiles and environments and I strongly recommend the Bio-Fin to all swimmers and divers, civilian and military.”
- David A Bucknam SSG USA, U.S. Army Rangers
The Executive Officer of the Special Forces Underwater Operations School stated “I have been extremely pleased and impressed with the performance of the Bio-Fin. I have tested it in all types of profiles and environments and have found it to be superior in all respects to any other fin I have tried. Normally to obtain optimal performance I have to switch fin types depending on whether I’m diving or surface swimming. The Bio-Fins deliver superior propulsion in both profiles and in heavy current. Most importantly to the combat swimmer, increased efficiency means less gas consumption, giving the operator more subsurface infiltration/exfiltration time, and so increasing the chances for mission accomplishment.”
- Joseph Diekemper LT United States Navy
I well remember a call from a salty Master Chief after we had sent them a size run of our first shipment of bio-fins so they could evaluate the fins: "Well, I've got some good f-cking news for ya, and some bad f-cking news." I asked for the bad news first. The Master chief said he had taken the fins out of testing. The good news was "They work and until they all have them I can't have people trying to keep up with those who don't. These are SEALS, they won't quit until they cramp and can't move."
We are not the only fin used by our armed forces but we do sell quite a few to those who care not about brand name or marketing. They simply want what works for their mission.
fnfalman
Contributor
I'd like to think that I can afford better gears for myself than Uncle Sam equipping GIs with gears purchased from the lowest bidders.
fnfalman
Contributor
You're right. Hmmm...what about because of the split, the water being channeled back as an expanding vortex - a sort of controlled eddies? That would explain why big kicks don't do anything but wasting energy but small kicks with fast cycles really drives the split fins?
Bubbletrubble
Contributor
@lmorin: I agree in principle with what you're saying. However, from a fin manufacturer's perspective, why even bother with doing any real R&D studies when one can effectively market the product by using testimonials from Navy Seals or other military special operation forces? By and large, the consumer public is stupid. People think: "If it's used by elite military forces, then it must be the best gear in its class and it's probably worth the additional cost." Navy seals have different goals when selecting a dive fin than the average recreational diver. They also have a different level of fitness and may have different kicking form. It's also unclear whether the military folks were somehow compensated (money or free fins) for their endorsement.Also, a critical part of any swimming efficiency analysis is the amount of drag created by the fin in question. It seems to me that any fin with a split would have more drag than one that without, simply because of the small currents/eddies coming from the two edges of the split in the fin. Most fins have little devices on them that, in all likelihood, increase drag rather than decrease it, despite what the manufacturers say. This includes buckles, water guidance channels or little fins, and especially the rather large empty space around the foot pocket on the underside of most open-heel fins. If someone/company actually wanted to corner the fin market, they'd test all available fins with an artificial foot and leg under standard laboratory conditions and end all this "discussion" once and for all. Right?
Military testimonials. Gotta love 'em (from a marketing perspective).
Bublletrubble:
No compensation at all to any military personnel for any comments or endorsements. Mike asked a question about military testing and I provided a response. We have never used these comments in any of our advertising, catalogs etc. That is not what we do. What I am attempting to do here is to answer legitimate questions.
No compensation at all to any military personnel for any comments or endorsements. Mike asked a question about military testing and I provided a response. We have never used these comments in any of our advertising, catalogs etc. That is not what we do. What I am attempting to do here is to answer legitimate questions.
Bubbletrubble
Contributor
@mdb: To clarify, your company did not give "free" fins, discounts, money, or any special "consideration" to military personnel or any U.S. government entity in exchange for being able to use the testimonials that you reference and that are posted on the following website, right? I realize that the website is run by Nature's Wing who holds the patent license to your fin design and you probably have limited input (if any at all) into its website content.
I'm not criticizing you for obtaining direct or indirect military endorsements at all. I'm just pointing out that it's effective marketing. Force Fin does it. APS Mantaray has a Navy Seal endorsement on its website, too.
Excerpted from the Apollo Biofin (Europe) website: : : Apollo Europe : :
hypersonic
Contributor
If the Bio-Fins are right for the Seals and Rangers then they are probably not right for me since I have neither the strength or endurance of a Seal or Ranger.
FWIW, I am a graduate aero engineer and don't believe any of the gibberish or the diagrams the marketing types put forth regarding thrust or lift or comparisons to a propeller. Fin's aren't wings and while they propel, they are not screws. The unsupported use of technical terms to hawk their product is a real turn off. And I consider Bob Evans with his line of Force Fins featuring vortex generators and winglets and after-burners (well he is working on the AB, probably shouldn't have mentioned it) to be just another snake oil salesman.
This is not saying Bio-Fins or Force Fins don't work but rather don't work for the reasons they claim.
What is important IMHO are the basics...the area of the fin, the ratio of width to length and the stiffness. Find a fin that is right for you based on your strength/endurance, the conditions you dive, filter out the hype and enjoy your diving.
FWIW, I am a graduate aero engineer and don't believe any of the gibberish or the diagrams the marketing types put forth regarding thrust or lift or comparisons to a propeller. Fin's aren't wings and while they propel, they are not screws. The unsupported use of technical terms to hawk their product is a real turn off. And I consider Bob Evans with his line of Force Fins featuring vortex generators and winglets and after-burners (well he is working on the AB, probably shouldn't have mentioned it) to be just another snake oil salesman.
This is not saying Bio-Fins or Force Fins don't work but rather don't work for the reasons they claim.
What is important IMHO are the basics...the area of the fin, the ratio of width to length and the stiffness. Find a fin that is right for you based on your strength/endurance, the conditions you dive, filter out the hype and enjoy your diving.
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