www.smartfins.nl/
self-adjusting camber on the fins? might be a revolutionary product
really?!?haven't fully read how it works! but i guess it's flexi enough in the upper portion to adjust to pressure..nah am not a fin techie
Pretty nifty if it works, they must have got the middle section to flex through rather than have the trailing edge flex off. Yes? it has to be like the sails pop through for the asymetry to be the right way. But it should be one pop rather than progressive flex. Remember those click clack beetles you used to get in the bottom of your showbag 45 yrs ago? You'd probably get a good old click clack going as you pumped onto the plane.
I think it's smart..
I'd do it with a stiff leading and trailing edge section each mounted in a pivot/bearing in the base, and a flexible (maybe some kind of mouldable rubber/plastic) middle section.. The more you pushed against it, the greater camber it would develop, and you'd still get the tip twisting away.
The immediate problem I can see (besides building the thing!) is oscillation - at speed, there'd tend to be a pulsing of load against the fin, and a corresponding pulsing of the camber - which would run the risk of getting out of sync with the rider, and causing 'fishtailing'.. You'd need different 'stiffness' of the flex-core for different speed and load ranges.
If this is important to you for speed just run an asymmetrical fin. I would have thought a decent folding or break-away fin system would be more valuable to those who want to avoid injury. Especially the speed sailors. I suppose you could ask people like Bertie whether they'd like their health back or to go 2 knots faster...
As a typical cynic I say great if it works, but what is the cost and how reliable is it going to be? I suppose that doesn't matter if your speed sailing as a fin probably won't last long anyway.
I'll probably get flamed for this, but you asked for opinions...
As Hardie alluded to, Decrep and I have tried to make a prototype with variable camber.
It's TRICKY!!!
The main problem is making the damn thing strong enough. Making something with camber that pops over isn't difficult, but think about the loading on a fin...
The benefits would be enormous -- you only have to sail next to someone with an asymmetrical fin to see the huge difference that it makes.
We haven't gotten past the proof of concept stage. The smartfins group have been promising this for a while, it seems that they're still not available through the website yet.
Nebs was sailing with me, he had a symmetric fin I had an assy. The difference in our pointing abilities in each direction was amazing. It was as if we were sailing in different winds, our natural runs were about 15deg different.
If my fin's camber had been able to swap sides, I would have been able to outpoint Nebs by almost 10deg in both directions.
But as Neb's says, strength is the issue, the front and rear "posts" or whatever is used, is under all the load that is normally taken by the whole fin.
so this supposedly 'smart' fin is fairly new! and you oz guys have tried tinkering with the idea..great for the sport this might be the one to break all existing speed records with ease..now i'll try ringing up a dealer friend and shock him with this new invention let's see how his all-rounder knowledge of the best fins stack up to this onehe didn't even know about choco fins that i learned thru you mates till he saw it in the Cobra factory and was a bit amazed
he didn't even know about choco fins that i learned thru you mates till he saw it in the Cobra factory and was a bit amazed
Some big yachts like America's Cup boats have assymetric keels, although in their case the assymetry is created by a trim tab on the trailing edge. However, all the America's Cup designers and aeros say that you don't actually improve pointing; effectively they just allow the hull to be rotated bow-down while the keel makes the same leeway angle.
I remember hearing about a Thunderbird yacht (26') in South Australia about 30 years ago had an assymetrical tacking keel - I think it was set up as suggested here with pins in front and back sections and the mid section moving to windward due to the side pressure. Fantastic in its day and really performed in certain conditions - I think the problem was not being able to adjust the depth of the camber whilst sailing, and huge maintenance issues.
WS Fins - So with a variable camber - the more pressure the greater the camber induced? Is this the best solution - so more camber when pumping up onto plane/upwind etc, but less when fully powered downwind and lighter back foot pressure?
gets me thinking what is the holy grail component of a windsurfing rig to get past the 60kt. mark..people might be looking at the wrong part all along and discover that all that had to be changed was the mast trackposition like the olden day short boards way up front
maybe something like this could work
you still have the two goal post, but the base of the fin is supported by a 'finbox', which is shaped so that it can accommodate the fin on both tacks. Might also help maintain a bit of stability in the fin profile.
Doesn't fit on existing boards without a bit of surgery thou hehe.
