Tuesday, August 5, 2008

Fins are Fins are Fins ! Or are they ?

Yes I know… an entire blog on fins ???? Am I finally losing it ? Perhaps, but then again fins seem to be cropping up in my conversations these days. You see I am a fan of the Scubapro split fins… and Gerhard (active technical instructor and firm believer in Hogarthian that he is) believes in the more traditional jet fins. Now as you may have come to realize, I tend to view all dogmatic idealogy (especially in diving ) with circumspection, so I get totally suspicious when I get told that there is only one fin for technical diving. The burning question is, is there really a fin that is superior when it comes to technical diving ?
It seems that most instructors and die hard hogarthian (and dare I say it, DIR) divers prefer the jet fin. Owning a pair I have to say it can not be a preference based on pure appearance because they look bulky, uncomfortable, heavy and squat. It is basic, basic, basic with a lack of flexibility in the foot pocket that simply screams sore feet. They are also limited when it comes to colour choice coming in black, black or black (seriously, must all technical diving be done in black ? Can we not get a little more adventurous and maybe try something in navy ? Or heaven forbid yellow, green or even yes..,wait for it… pink ?).
The jet fin boasts a design that is at least 30 years old and a philosophy of sticking to the basics and keeping it simple. Being manufactured out of negatively buoyant rubber they are heavy, which is not a bad thing if you are in a dry suit as it eliminates annoying floating feet and ankle weights. Their manufacture also ensures that they are stiffer than most other fins which makes them feel like you are wearing a pair of planks but having said that this rigidity does mean you have far better control underwater. They are almost designed for modified flutter and frog kicks (which as you no doubt know are essential anti-silting techniques). Because they are extra stiff they are much better suited to high current diving (not really an issue for us South Africans) not to mention propelling heavy and bulky (read drag prone) gear through water both of which are a definite plus.
The jet fin also has one other element of design which proponents wax lyrical about, the straps. One of the first lessons I learnt as a technical diver was to tape up my fin straps to avoid them getting caught on lines etc. The irony of which did not escape me when I found myself with one fin caught mysteriously on the line at 152 meters. Truly the last thing I excepted to go wrong on that dive was getting trapped on the line and I ended up with the choice to either cut the line (which I was not happy to do being as I was in a confined space in a silt out… yes, I could use the walls and positive buoyancy to get out but the risk of getting further entangled in loose line was not appealing) or I could leave the find behind. Which I did. I still do not know what it trapped me…but one of these days I will go back and retrieve that errant fin and hopefully find out what.
Which brings me back to straps. The jet fins come with the most primitive straps you can imagine. In fact they remind me more of Sean Connery James Bond diving gear than the gear we are familiar with these days. Firstly there are no convenient plastic clips for getting in and out (which incidentally is how I got out of my stuck fin. I shudder to think of trying to remove that fin without convenient buckle to release). Instead, the strap connections are moulded into the fin. This means that there is no leading edge groove to catch on line. The straps are also arranged in such a way so that the ends are on the INSIDE of the rest of the strap. This presents a perfectly smooth surface on the outside of the strap and clip area so entanglement is virtually impossible. The down side is that they are a pain in the but to adjust, but then again I think I would rather have that problem then be stuck.
To summarise, the benefits of jet fins (the preferred technical fin) are?
- They are negatively buoyant which is ideal for dry suit divers
- They do not have plastic clips so you avoid the situation where you can’t dive cos you have broken a piece of plastic
- The entire strap is designed to present a smooth surface and so avoid catching on anything
- The blade is firm allowing for better speed and less silting using technical finning techniques
The cons are :
- They are heavy and so more work than something like a split fin
- They come in black, black or black (admittedly not a serious con, but still)
- They do not have an easy to release clip which means getting into them and out of them when dressed in layer on layer of warm stuff is a problem, especially in a dry suit that does not have a telescopic torso.

So what are the alternatives ? My favorite fins are the SCUBAPRO SPLIT FINS. Firstly, they are light so you do not have the feeling that your feet have suddenly turned to lead. Secondly, on a straight scissor kick they are fast and effortless (I was seriously surprised when I tried mine out…spent my first dive checking that the fins were still there and being amazed at the turn of speed I could muster). Oh, and they come in something other than black (a nice neon green for starters). They are modeled on nature (specifically the tail fin of a Humpback whale) which is capable of shifting tons of water with a single stroke. And they are fast being designed for speed and minimal effort (features inclide a patented split fin propulsion system; patented drag reducing vents that reduce drag on both the up and down strokes and an extended sole plate to increase leverage and power output). Simply put a split fin is designed to produce more forward motion with less effort using a scissor kick, which is where the problem comes in.
The last finning technique I find myself using in a cave is the scissor kick because whilst it generates speed, it also has too much downward force and so it generates silt and silt is every technical divers demon. I have been using my split fins for a while and so manage to avoid silt… but at the cost of speed which is an issue, especially when you want to do a long exploration and are on a time line. The problem with the split fin is that the lightness and effortlessness comes from a blade that is just too flexible. This flexibility makes for comfort but makes it more work to move heavy bulky gear through the water.

In a nutshell, split fins are :
- Lighter with a more flexible blade which is a negative for technical diving as it makes floating feet worse and means more silt and less speed when navigating heavy kit around narrow tunnels.
- They do have easy release clips (which I am still a fan of) and do come in a variety of colours (yes, colour is important but perhaps not that important J)

The sad thing is that whilst I love my split fins I have moved back to the traditional jet fin simply because of their superior performance with regard to anti-silting and speed. Do I like them ? Nope, not much… yet! But I am sure after a couple of months I will no longer remember the light and pleasant split fins and instead be comfortable with what feels like two small planks that remarkably have the ability (against all appearances) to enable me to turn on a tickey and dive in a silt free world. The good news is that Scubapro makes both, so at least I have that.