The RK3 standard and the RK3 HD's are both exactly the same fin. The HD is not "tech" any more than the standard RK3's are. They are exactly the same fin. The difference between the two is the density of the rubber. The standard fins are "less dense" than the HD fins (high density). This means the standard fins have more flex, and are positively buoyant, while the HD fins are stiffer and negatively buoyant. Otherwise, they are exactly the same fin. The term "RK3" comes from "Rocket 3". The RK3's are the THIRD generation of the classic US Diver's Rocket Fin, developed originally for the US Navy, and still issued to this day both Aviation and Surface Rescue Swimmers. The Jet fin was created by ScubaPro for US Navy use by divers, and it's design is made intentionally for that purpose--diving underwater. While the Rocket fin was intentionally designed specifically for swimming on the surface. Rocket fins are traditionally shorter, stiffer, feature a central rail for added reinforcement, do not feature the hole line along the edge of the blade vents, and the blade is pointed, opposed to the Jet fins. In 2005-ish, Aqualung came out with the Rocket 2's (aka, the Super Rockets), which became the standard issue Rescue Swimmer fins after that, while the REAL, actual Made-In-America, ScubaPro Jet fins are still issued to this day to divers (rubber strap and all, no spring straps, those are made in Taiwan). A few years later, both the US DOD and British MOD opened competition for a fin design to meet newer demands by combat divers. Apeks developed a fin based on their stated demands, and the new fin became extremely popular. When Aqualung bought out Apeks, they wanted Apeks to become their "premium" line. The fin was rebranded as the Rocket 3 (third generation rocket fin), and released to the public for sale, and thus, the "RK3" was born.
Looking forward to the rest of the series. As a fellow quattro/power plana user I think I'll be able to relate to your experiences. I was kind of hoping to see the Zeagle Recon in there, any chance of adding it? It seems like an illegitimate lovechild of the quattro and the power plana in that the shape is very quattroesque, but the material and dimensions resemble more the PP.
I’m hoping to get back out that way in early July. I’ll keep you posted. I can’t wait. I’ve been keeping an eye on your weather conditions report. I’ll be seeing you soon my friend.