Bought some new swim/bodysurf fins after the old ones died of finrot, but the short fins lack power Vs the original longer ones. I’m not buying another set so I figure to revise the design.
Basically add more area but minimal length.
The power is in the down kick / stroke so the added area is on top of the current blade because it’s upside down when used.
It should have more blade area than the original large fin and the proximity if the twin blades should give it some real squirt !
Jrandy, yes that the plan, here’s the top view and the end view.
The spacers I’m guessing only need to be about an inch high and the additional blade area is about an extra 30 sq inches.
the side spacers should act like up turned wingtips concentrating and holding the flow between the blades rather than letting the water spill off the sides.
The red is the original fin and the black is the side spacers and new blade.
Made the Aluminium brackets, inch high, but they’re not going to look so chunky as they do now. I was going to make the whole thing out of glass but this way I can do the Aluminium brackets in 30 minutes and then vacbag panels and swap them around.
Your swim fin looks like a combination of your foils & tunnel fin concepts, plus your penchant for aluminium added to a pair of swim fins. Drop-ins shouldn’t be a problem.
I thought of that too Dave, but the side panels didn’t have any noticeable effect.
Today was a freakin gale with torrential downpour so I didn’t leave the house much less get in the surf but I’ll test the new version ASAP. On the good side I spent all day in The Shed making stuff.
Bob, I wondered if I might cut a leg off with the aluminium but no chance.
When I saw the set up, I was wondering how it would affect fin flex.
Can you add/use flexible spacers? Maybe rubber rubber rods/cylinders or rubber hose/tubes for spacers? With flexible tubes/hose you could vary wall thickness to adjust flex – play with diameter too.
Still experimenting with fin/ flipper design as well as many other things.
A fin needs to have area, stiffness and a solid connection with your feet to allow the instant transfer of energy from hip-leg-knee-ankle-foot-toes then flipper to water.
The last version with a split level setup had propulsion but it wasn’t smooth like the big Voit Duck Feet on the left. They’re the best at getting forward movement, IMHO.
The middle ones are highly regarded but don’t have the area or stiffness for instant giddy up when you really need it. They can twist on my foot because the pockets not rigid enough or maybe I have little girls feet.
so I’m back to the modifications, but this time the addition is on the same plane as the flipper blade. The 2 on the right are the top and bottom view of the latest creativity.
The push from a kick seems to be mainly on the down stroke with the up stroke being more or a reset stroke so I’ve attached the additional blade to the top of the original blade so it’s strongest on the down stroke.
It’s just 5 mm ply with paint to waterproof it for testing.
Greg, the creativity covers a wide field, Including building my own backyard pool, a few medical items, shaping shed, house extension, decks, underwater breathing system, dining table, fishing lures, child’s safety swing seat, handplanes, a wheelchair, pram slide for steps, and a ton of things I’ve forgotten.
So I trimmed 3/4 in of the end width and they’re easier to use, too wide and they hit each other when youre kicking.
Another thing I dislike in flippers is not enough toe room.
Ive got Schrek Feet and when there’s not enough toe room my nails get ripped apart.
im thinking that the most comfortable flippers would have open toes and while some commercial flippers do and don’t have open toes, it’s probably more about their method of manufacture than comfort. You can see how many different companies are made in the same factory by the samples behind the woman in the video below.
Interesting you’re adding on to fins. I’d just get those long diving flippers and practise slow kicking. Holes and bolts in fins always seems to lead to tears.
I know wave catching requires quick bursts of speed from fast kicks, but I’m not convinced that bigger/stiffer fins are that much help. I’m 59 and have been kneeboarrding over 45 years.
Personally I gave up on Churchills, Voits, etc. years ago. I get the cheapo swim fins, cut out the heel, add a loop of string for fin tethers and trim the blade curved at the front and grind the edges down. I’ll post pics.
I’d like to see what you do to the flippers please.
From my experiments I’ve found bigger area and more stiffness creates lot of resistance to the downward kick, the upward kick is more of a Reset than a useful stroke, especially if you’re only able to kick from the knee and not the hip.
The Voit Duck Feet were the best so far with a larger blade than most, all the smaller ones were less effective. The soft silicone ones had all the fancy side flanges to stiffen the blade but theyre still too sloppy.
The foot pockets were where the designs make a difference, they all have a lot of room for your toes and any pocket that touches your toes tends to wear and you naturally cramp your toes to push if your toes can touch the pocket. The heel straps are all about the same design with a bigger cutaway under your foot than on top.
Your foot is held in the pocket by the top and bottom of the pocket, on the DaFin the top is quite thin and I felt the fin wasn’t delivering the kick I was giving. Even with the rubber flippersbeing stiffer most had side panels along the fins for more control and to hold the water during each stroke.
The design of current flippers is due to the manufacturing process and materials so I working on making a glass version that should give me the ability to control the flex and a comfort fit.
I’d be interested to see your pics + the tethers. I have experimented with different cords and knots a bit.
Brett,
Flippers are such a personal thing. I also come back to Churchills but the fit is terrible and the rubber much harder. The stiffer duck feet are also heavier - great for the conditioned legs but agony if out of shape. How do you find adding to the fins - ever hit bottom or anything else, with them. I have plenty of reef and rock scrapes.