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Author Weed Fins
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WA
77 Posts
Posted 07/08/2010, 4:30 pm        Report    
Awsome YoYo, I cannot believe how close it is... look great!! yeap, like I was saying, the Select are thin, thiner that most of fins, and pretty sure more that the Ka! Now I think we are in trouble It is great for Lao to have both, it give him some variations, be able to use the Ka with a bigger board.. I heard he bought one... cheapo I can just imagine people now will playing with their fins Thanks for sharing..
WA
1007 Posts
Posted 07/08/2010, 4:41 pm        Report    
A selection of weedies and rough measurements Top left elmo JP 40 something slalom to 29 470 143mm base 42mm widepoint 11-12mm width. Top speed 37 normal 34, lots of sessions, JP slalom II 84, 54 wide. Top right yoyo kinetic 36 to 27 450. 128, 45, 11-11.5. Top speed 36 a few sessions, cut down 270 to 245, 51cm wide slalom board Mid left elmo select lightning evo 35 to 24 450. 123, 42, 8-9. Top speed 42+ lots of sessions and close to 37 through chop, cut down 270 to 245, 51cm wide slalom board Mid right Flying objects 26 450. 130,38,11. Top speed 38 in perfect conditions, not good in chop spinsout 33 ish normal lots of sessions. JP FSW91, 60 wide Bottom left KA 23. 127,37,9. Top speed not tested. Bottom right 31 to 22.5. 116, 34, 7.5-8 400. Top speed 36 one session. cut down 270 to 245, 51cm wide slalom board Despite similar wide points 29% for all except the Kinetic and Evo at apprx 35% the thickness profile varies significantly. KA carries the thickness through to the tip more than the others. FO very thin in the trailing third.
VIC
1549 Posts
Posted 07/08/2010, 6:37 pm        Report    
Nice job and write up Sam,i just might rebox some Selects that i no longer use cos they were horrible.Not that we have much of a weed problem but could be good for an epic Swan bay session.
WA
5429 Posts
Posted 07/08/2010, 8:10 pm        Report    
samOZ said...
Greaaat job Mike, like always.. I love the shape and color mix, shame the carbon with cover it!! Your fin is what I am talking about not sure about the thickness of it? How thick? >>>>
You've seen this one Sam, but as you say it looks different with the carbon on it. It's the one in my big yellow board. It's 31cm deep 15cm wide at the base and 13mm thick, so that gives it a flow to thickness ratio of 8.7% It's not meant to be a speed fin, it's meant for light wind early planning. Ian Thickness of glass/carbon would be between 1.5mm and 2mm Here's the finished product, I took this photo, when documenting my weight loss attempts. The fin looks scratched, that's just my 80 grit sanding marks on the initial bog job, before the spray on filler undercoat, it's finished with 600 wet&dry, and is nice and smooth. The strap is one of keef's experiments, works well and very comfortable.
WA
77 Posts
Posted 07/08/2010, 8:32 pm        Report    
Mike! yes, I seen that fin close up! This is just manificiant work I say, you are such an artist I have to say I am not that thin in the job in comparaison? Buuut I have an escape way which I will explain soon... which is for me one of the key of rock stable speed weedfin!... some knows I am sure Your fin remind me my Lessecher Duo 28 light wind fin You could easy carry a 7.5, even a 8m on 110-20 board! I would be very happy to try it Mike if you let me to!? It make me want to make one too now.. something more performant that my Duo!
WA
1304 Posts
Posted 07/08/2010, 8:33 pm        Report    
cheers Sam!! the reworked drake(40) looks great!! The story behind this fin is, it came with my original iso 105 and felt like crap as an upright slalom fin. i decided to make a weedy out of it prob 4 years ago. i took to the leading edge with a flat bastard file and thinned it out to a point, touched it up with some 150grit and left it at that. Although it never felt fast, it did its job as a weedy and to this day it NEVER!! let go. Its great to see it being reworked by Sam. I have checked out a few of his fins and i have to say they all look great! he def has a great eye for it! cheers mate. The drake 34 that also came with the iso became my 22 weedy for my ca 40..at this stage it holds my 2 sec/10 sec/nmile and alpha pbs..it got the same finish as the bigger one. might look at getting Sam to look at this as well..only kidding mate!
WA
77 Posts
Posted 07/08/2010, 8:50 pm        Report    
No worries Snides The problem I have to work better that if its was mine The fin will be perfect for your 54 board with a 6.5.. speed, I am guessing around 35, 37 maybe with a 5.5.. just guessing! With the rake given @ 38-40 and 25.5, I would not venture too much in hards run with it unless a good tide
WA
313 Posts
Posted 07/08/2010, 9:01 pm        Report    
The simple way for a quick weedy is to take a 32cm Flying objects weedy, cut the bottom off so it is 23cm and file the rough bits, then after you hit a rock file a bit more off, this fin is good for 40 and rock solid
WA
5429 Posts
Posted 07/08/2010, 9:45 pm        Report    
nebbian said...
decrepit said... . I've had it just over 30kts with a 6.0 sail, in just over 15kts
Wow! I want one!
Well we measured 15 on the beach, was probably a stronger gust that got my 30.
WA
77 Posts
Posted 07/08/2010, 10:38 pm        Report    
Thank you Kato, this is such an important subject I think.. I try, we try our best! I think experiences and knowledge have to be shared... Lao, nice to see all your weed weapons , I have no chance to pass you now, not like I did.. that cool to me Your display is perfect, that will save me some photos for one of the most important part of what work and what not in matter of the design of the speed weedy! The information I give here is like all the rest before, it is by what I found when testing, for my weight, my gear.. but pretty sure that will fit 80% of the people It is for everyone, mainly for people that don't know about weedies! That will save you time and money (not like me, I learned the hard way!). Test made on choppy water, flat is more forgiven!! We talked about the lenght, width base, the thickness, the surface area.. now I would like to talk about the shape of the area! Lot of us would have guessed already! I will use 0 for STRAIGHT, - for IN, and + for OUT, this is for the lenght of the fin.. remembe we are talking high speed weedy, 35+ and stability ps: when I say 0/+ I mean straight for the first 3/4 of the leading edge, then 1/4 + curve closing!! I know my explainations sound a bit.. sorry * 0 leading edge & 0 trailing edge WORKS, limited in high speed and spins >> 35+ kts like the JP above (had one in my early tests) * 0 leading edge & - trailing edge WORKS, very limited in high speed and spins >> 33+ (amazed Lao you had 36 with the Kinetic!) * -/0 leading edge & -/0 trailing edge WORKS, good high speed >> 40 tested stable with my special, can go higher.. don't laugh I ll explain later..similarity to the Flying object * + curve leading edge & - curve trailing edge BIG NO, very very limited, 30-32 and spins * + curve leading edge & + curve trailing edge WORKS, very limited in high speed and spins >> 33+ * 0 leading edge & + curve trailing edge, WORKS, good high speed, one of the best like the LAOs lighting >> for me around 36+, Lao 42+, was on flat was it? * 0/+ leading edge & + cuve trailing edge, WORKS, good high wind, the best in my book.. like the LAOs Ka and Select >> 38+ with my SS ultra, can go higher. the Lao's select raked @ 35-37 given his thickness! would definitly be a killer Dam Lao, you are a trouble maker!! I will carry on tomorrow with some photos of few of my fins, some explainations, and the key of a rock stable speed weedfin nooh we not finished yet
WA
3675 Posts
Posted 08/08/2010, 7:59 am        Report    
mY 2 CENTS (I'll make it short) Weed fins = Control Why = More rake Cost = less lift Who will benefit most = Average to sub-elite sailors & and people that sail in v shallow, grassy or weedy areas
NSW
1272 Posts
Posted 08/08/2010, 9:39 am        Report    
Starting to see your point Hardie. Through the years I'd noticed the odd sailor choosing to use weed wins in clear water. Very odd? Now I fear I'm turning into one myself. Lake Illawarra forced me to use one and now I'm not bothering to change the fin when I go seaside. I think you notice the advantage when the nose of the board gets pitched up. A vertical fin goes into that point-first jousting orientation. Feels sketchy. So what are the tricks to moulding new bases? What sort of brew do you pour in?
WA
1007 Posts
Posted 08/08/2010, 10:05 am        Report    
hardie said...
mY 2 CENTS (I'll make it short) Weed fins = Control Why = More rake Cost = less lift Who will benefit most = Average to sub-elite sailors & and people that sail in v shallow, grassy or weedy areas
"Average to sub-elite sailors" I feel so proud to be one!.
WA
77 Posts
Posted 08/08/2010, 1:46 pm        Report    
hardie said...
mY 2 CENTS (I'll make it short) Weed fins = Control Why = More rake Cost = less lift Who will benefit most = Average to sub-elite sailors & and people that sail in v shallow, grassy or weedy areas
Good point Joe , you loose the lift and that is why people don't like them!! More you had rake, more you loose the real drive of it because it flat everything! This is why also I try to keep mine between 35-40 / rake so I have the best of it. I never had a chance to try my fins on real flat water (like S.P).. I do have speed fins too which never get used. Ian K: Very odd? Now I fear I'm turning into one myself. Lake Illawarra forced me to use one and now I'm not bothering to change the fin when I go seaside. I have to admit with the years sailing on weedy has reduced dramaticaly my sailing skills on normal upright fins.. I notice that heavier people can drive thicker fins further.. like Adam with is FO cut off 23 or Elmo with his brochetta of JPs I am sure somewhere we are not far off a good mixture for a great speedweedy.. I wonder if there is out there some people with some ideas!?
WA
77 Posts
Posted 08/08/2010, 7:50 pm        Report    
Surprised nobody has answered to Ian!! Ian K: So what are the tricks to moulding new bases? What sort of brew do you pour in? This is the way I do it.. make sure you add some fibre meshing!! not like me too many times The self leveling boxing mould is made of silicone, and peels off sooo easy .. I just black marker the base when finished.. (you can use colors to mix) Some people have some more fancy ways..
WA
762 Posts
Posted 08/08/2010, 9:19 pm        Report    
Some people use the powdered mesh with a chopped strand matt reinforcement, but around the barrel nut it's important that IT breaks if you hit something and not rip out the fin screw through the board. just found my card reader Sammy!
WA
762 Posts
Posted 08/08/2010, 11:05 pm        Report    
The first image shows the rig and split mould this next image shows a lessacher duo weedie reboxed at 38 degrees with a refinished surface and swept up trailing edge. next is the reboxed choco 40 cm at 38 degrees with the same sweep at the trailing edge but the chord has been moved to 35 percent . now for the last one, I've shifted the chord back about 5 percent on an mfc that was'nt doing so well, making it about 40, cut a bevel in the lower trailing edge (so if you hit something the fin does'nt cut a neat groove in your brand new board) and taken a nasty bend out of the fin itself. It's now ready for tomorrow
WA
77 Posts
Posted 09/08/2010, 5:17 am        Report    
Great stuff Paul, it look great.. first time I see your jig!! Is it the same way that Elmo did his? I was trying to visualise his and could not quite! He was talking about a back board with angles on it.. must be similar is it? You made a little anti-spin noch on your fin I see For the people that still don't know the answer for "rock stable home made weedy @ 40" (I did give a hint early!) here it is: Nooh it is not putting more rake to the fin! Add a concave the long of your trailing edge on both side "symetrical". This is Claude's 40kts+ SS_WING 230/30, one of my early good fin made almost 2 years ago. I did exagerated a little the concaves, you don't have too! I have not try on normal slalom fins under 30/rake. Some people going to say aaah I knew that, some will say why I haven't thought about it before!! What I noticed is most of the slalom fins out of the shell does not have it!! They all have a nice long curve from leading to trailing, sometime so hard to see, it look almost flat. I realised this about 2 years ago when playing with this chocking fin originaly not working more that 30 knts. Anyway this is a Wo Duo, double-assy, it is when fixing it and playing with the concaves that I had the light! Even the fin was bad (you can see all the work I put in!), it would not spin! This fin now is rock solid and drives @ 36, the force apply each side will force the fin to drive straight. I only finished it 6 months ago!! Because it's 11mm tickness I cannot go higher in speed.. I may have to get it tested by a big boy in the team To finish my bla bla in this topic I am only going to show you parts of my SS_Special experimentation which took me to 40kts and explain the idea behind.. sort of!! we don't laugh please... Here some mesurements so we have an idea: 225/40, 117mm wide at the base starting @ 10mm thick to 3mm @ 30mm from tip (my thinner so far) I took the idea from my Tectonic "Gold Wing" 34, nooo I could not just rake it, I would loose the angles, the area, too thick at the base (11mm), etc.. So I modified the angles to make it fit to my fin!! This is my 3 speeds fin.. Actually, YoYo and Lao was not far of with the Kinetic (I want to apologise guys.. I was thinking about - curve, you have -/0 followed by + curve) Some will think it is like the FO.. well, not at all, the FO has - curves then + on the trailing edge (I don't like - curve), also it has a + curve on leading edge (which work for some, definitly not for me), and it is too thick anyway.. With the wide base & 10mm thickness & 20% of concave, the fin goes upwind like a charm even with his 40% high point! You can see how smoove is the entry point.. When travelling and accelereting, the fin pass from the first part | / of the fin to the 2nd part / /, as you accelereting more and going down hill you pass to the 3rd part | / Between the 1st & 2nd part we have eliminated some area, the fin can go faster.. between the 2nd & 3rd the fin become thinner and we add some + almost square to the fin which helps to drive the fin on the tip.. I like so much that fin that I made a 245/38 version.. not full tested yet I want to wish good fun and experimentation to all , I have the feeling that we going to see more weedies around this summer
NSW
1272 Posts
Posted 09/08/2010, 9:23 am        Report    
Thanks for the insights into the art of weed fin construction. Silicon moulds for the bases! Which got me thinking. How would you incorporate a bit of rubber into the fin base to allow it to flex right at the root of the fin? The physics is overwhelming. 90 degrees ( talking in the across beam direction now not fore and aft) is not the optimum angle for sailing on a starboard tack. It'll be something less. Though 90 degrees is a good compromise if you also want to sail on port tack, so it makes sense that that is the usual setting.
WA
762 Posts
Posted 09/08/2010, 10:36 am        Report    
Ian K said...
Thanks for the insights into the art of weed fin construction. Silicon moulds for the bases! Which got me thinking. How would you incorporate a bit of rubber into the fin base to allow it to flex right at the root of the fin? The trouble would be getting something to adhere to the rubber. Silicone box maybe?? Don't know how it would perform under load or how long it would last. I think there's enough flex in the fins anyway. Have a look at peconic puffin (fin flex)
NSW
1508 Posts
Posted 09/08/2010, 12:13 pm        Report    
samOZ said...
Surprised nobody has answered to Ian!! Ian K: So what are the tricks to moulding new bases? What sort of brew do you pour in? This is the way I do it.. make sure you add some fibre meshing!! not like me too many times The self leveling boxing mould is made of silicone, and peels off sooo easy .. I just black marker the base when finished.. (you can use colors to mix) Some people have some more fancy ways..
that looks easy samOZ, do you have problems with air bubbles in the brew when its cureing, if so how do you get rid of them it seems to be when moulding the bigger the brew the bigger the air bubbles
WA
77 Posts
Posted 09/08/2010, 12:57 pm        Report    
Keff: do you have problems with air bubbles in the brew ? I do get the ocassionals ones, usually near the blade! When finished the mix, wait 5-10 mins (you will see them forming,coming up), you have time.. pouring only takes few minutes. Try to don't mix too hard! If still appear after.. take a needle and pop them out
QLD
New Zealand
113 Posts
Posted 09/08/2010, 1:12 pm        Report    
Ian K said...
Thanks for the insights into the art of weed fin construction. Silicon moulds for the bases! Which got me thinking. How would you incorporate a bit of rubber into the fin base to allow it to flex right at the root of the fin? The physics is overwhelming. 90 degrees ( talking in the across beam direction now not fore and aft) is not the optimum angle for sailing on a starboard tack. It'll be something less. Though 90 degrees is a good compromise if you also want to sail on port tack, so it makes sense that that is the usual setting.
The toughen rubberized epoxy resin that we use for our Fin Bases has certain amount of give, this toughen rubberised epoxy resin could be modified to allow more flex. From engineering point of view the toughen rubberised epoxy resin is great for fin bases as the stress load at the base of the fin is spread to absorb the shock.
WA
1787 Posts
Posted 09/08/2010, 1:52 pm        Report    
To get rid of any bubbles just use a small blow torch.( what chefs use) This pops the air bubbles really well and give you a nice smooth finish.
WA
762 Posts
Posted 09/08/2010, 1:56 pm        Report    
samOZ said...
Keff: do you have problems with air bubbles in the brew ? I do get the ocassionals ones, usually near the blade! When finished the mix, wait 5-10 mins (you will see them forming,coming up), you have time.. pouring only takes few minutes. Try to don't mix too hard! If still appear after.. take a needle and pop them out
Leaving the brew to rest before pouring usually sorts them out, the ones that come to the surface after pouring can be (gently) wafted away with a mini butane torch. Note that if you're using white pigment it will turn brown if the torch isn't wafted over the surface quick enough, so you can imagine what is happening with the brew itself. Still, it's the quickest way around those surface bubbles and lends a good sheen to the job.
NSW
1508 Posts
Posted 09/08/2010, 2:25 pm        Report    
has anyone tryed this
NSW
1272 Posts
Posted 09/08/2010, 3:30 pm        Report    
pepe47 said...
Ian K said...
I think there's enough flex in the fins anyway. Have a look at peconic puffin (fin flex)
But the flex is distributed, most at the tip, not much at the root. Wouldn't it be better to work out the optimum direction of lift and then have all the fin work in that direction? Which is related to the fundamental problem.. There are 3 forces on the windsurfer system. Gravity Aerodynamic forces Hydrodynamic forces. Gravity all acts in the one direction, no mucking about, straight down. Aerodynamic forces aren't too bad. Normal to the sail - apart from a little twist - all acting together in the one direction. Then we split the hydrodynamic force into 2 orthogonal components - vertical and lateral , a bit of a " What the?" don't you think. Be much more efficient if we could do it in one hit, as do kite surfers( if you ignore the mini fins on a kite board which can't do much) So bending a fin windward helps reduce that 90 degree angle between board and fin action. Shifting the gravity countering component off the board onto the more efficient fin is also a win. Why do we rail the board to leeward when going for max efficiency? It's the fin that is working better not the hull. If we could keep the board flat while doing this it'd be even better. We could mount a treadle under the front footstrap to control fin angle. If it all got a bit flighty drop the heel to bring the fin back to 90 and it'd all settle down. Macquarie Innovation had fin angles adjustable with a lever mechanism. It turned out they used 90 degrees for fear of the hull getting too light on the water. There was another speed machine which also attempted to concentrate its hydrodynamic forces underwater with the one optimally angled foil. Car suspensions are all mounted in rubber bushes, it's got to be possible.
WA
77 Posts
Posted 09/08/2010, 5:40 pm        Report    
Thanks Bendy, so simple never thought of it.. I will try Great stuff Keef , thats a good idea.. I did actually found with all the moulds I made that you get more bubbles with the silicone, and they come later.. Just have to build a vacuum chamber now, that will help with the epoxy... cool Ian K , I like the idea of the epoxy- rubber, I have been thinking about it for a while... since I saw Chris.L fins.. it look like he is using something similar!! Is it stable when it drys? I means it does not shrink! I would not mind having a crack at it.. Anything to add a mini knot to your speed is good Maybe silly question but, I have not understood yet how you put the inserts in... you don't see them! Do you drill the blade and put them before? Anyone could explain?
WA
Austria
1299 Posts
Posted 10/08/2010, 8:29 am        Report    
I think Chris is using a sort of urethane. It goes off pretty quick though ~10-12 min. Used to get a fair few bubbles but I think he has it sorted now. Boogie used to use a rubberized epoxy on his custom fins years ago and they were the cleanest bases you'd see.
New Zealand
195 Posts
Posted 10/08/2010, 6:32 pm        Report    
Here's an easy to make vac chamber for de-gassing your epoxy after mixing Its a length of 150mm drain pipe (5mm wall thickness) with 15mm acrylic end plates and foam rubber gaskets to seal the plates. An 8mm tube bolt threaded into the acrylic serves as the spigot for the vac hose I have another made from 300mm pipe which takes my gel-coated molds to de-gas them before doing the layup. Got the lengths of pipe from drainlayers on a nearby building site. I use the toughened rubberised epoxy mentioned by ice surf for my fin heads. It's called HPR5 and is available from Adhesive Technologies in Auckland NZ. They may have an Aussie agent? Its great stuff, you don't need any fibre , very tough and never cracks. Has the consistency of honey so has to be warmed up to use......quickly! A spoonful of graphite powder mixed in colours the resin and makes the head slide in the box nicely when its all set.
 
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