Mermaid fin vs. conventional flipper

[Andrew Buren]

This is just something I was thinking about...
would it be better to design a scuba flipper that has only one up and one down stoke for every cycle instead of the scissor kick? If so (or not) what would be the advantages and disadvantages?

 

[Mech_Engineer]

If you've ever scuba-dived and tried "mermaid kicking" with both fins together, you quickly realize it is a less efficient use of your gloriously separate legs. You will get tired more quickly and your drag through the water is somewhat increased because your whole body has to get into the act.

 

[Andrew Buren]

Yes I do dive. However, could it be posible that you think it less efficient because we are used to the conventional way?

 

[Danger]

I can't swim any more, and only used fins for snorkeling anyhow, but my impression is that a 'mermaid' kick would soon cause painful stress to your lower back muscles.

 

[LURCH]

Actually, with the right bit of kit, the dolphin-kick can be much more efficient than the scissors-kick. DARPA has developed http://www.popularmechanics.com/technology/military_law/4223354.html" for exactly that reason. They claim that while swim fins are about 15% efficient and turning muscle power into propulsion, this device approaches 80%. In trials, it has doubled the sustainable speed at which SEALS can travel underwater without a vehicle.

http://gizmodo.com/gadgets/military/darpas-powerswim-brings-out-the-aquaman-in-you-318195.php" that has a video of the device in action. I see that the guys who actually came up with the winning design are the same folks who invented the Seque^TM