You know how sails 'breathe' and twist off to keep control and deliver speed? K4 Fins do the same to multi-fin wave boards by designing a flex pattern that works with you. K4 Fins have created a unique and new material for windsurfing - OptoFlex is a molded resin long fibre matrix that has been carefully manipulated to provide the perfect flex patterns for windsurfing. K4 technicians took a long time to create the perfect material with the qualities needed to provide the performance. K4Fins are moulded using a plastic composite material giving them the correct flex and strength properties - similar to surfing's 'Glass Flex' FCS fins and 'Natural Composite' Future fins. They use the latest materials and processes as recommended composite experts and have been testing the highest grade materials in the lab and on the water for nearly two years, continually improving the aesthetics and the performance.

I have been extensively testing K-4 twin fins (17-16-15cm) in NZ for 12 months everywhere from Pungarehu, Kina Rd, Waitara, The Ditch, Takapuna, Orewa, Tawharanui, Managawhai Heads, Omaha, Auckland harbour... and the fins have delivered in all conditions from nasty choppy 'egg-box' sea states, to cross-onshore mushy waves and to prefect cross-off logo high DTL reef breaks. They rip and I cant see my use my G10 fins again in a hurry! Even though they seem so soft they don't spin out even in the harshest sea state and when totally overpowered!

The K-4 fins work awesome on the wave face. Sooooo much more grip/traction and torque off the bottom and top turns. You can feel the fins flex with the carve when really loaded up off the bottom turn but through the last quarter of the turn they then whip the board around and provide a extra squirt of acceleration to drive you back up the wave face more vertically than ever before!

The top turn on the K4 fins is something else. You can crank as hard as you like and they engage traction like a 4WD off the top and keep turning. You can feel the fins loading up and flexing but you get whipped around so fast and can 'round house' the cut back super hard into the breaking section, or do those new school super whippy cut backs. Also I have been doing the best and longest lip slides ever as the fins release easily off the top to initiate the slide but they come back in again just as easily to control the end of the slide and let you sail off feeling like a rock star!

Simply, the more energy you put into the initiation of a bottom/top turn the more performance the fins will then deliver back to you! The fins release the energy you put in at the exit of the turn in the form of a squirt of acceleration right where you want it!

I find they do work well in cross-onshore mush - when going for  tricky clew-first front side riding the fins will load up but then release off the top turn far easier than G10 fins which makes the top turn faster, slidier and tighter in onshore winds so you get drive through the whole turn - without dealing with that surge of rig power on the back hand when you are slow through the top turn. Also in onshore backside riding they power up hard off the bottom and keep turning off the top turn with all that grip so you can really be aggressive going for backside hits and importantly recover from tweaked turns at the point off the wind when you have to re-engage the rail to get back on to a reach again.

I have used them in Taranaki, NZ, quite a bit, which is rocky...like really really rocky and have had no issues with robustness. I have scraped them a few times but as the fin material is soft I have simply used my finger nail to tidy up the scrape and later on use a bit of light sand paper to take the roughness off. I reckon that hitting a rock with a K-4 fin you are likely to dent the fin versus smashing a thin foiled G10 fin to pieces!

Basically, I am doing turns I've never done before on my Mistral 84 twin fin and I have sailed that board a lot prior to swapping to K-4 fins so I know what the difference is! 

K4 fins  are lighter, looser and grippier than anything else on the market with test winning performance. This guide will help you dial in your board for ultimate performance.

RELEASE/GRIP: This is a choice you have to make. Do you want to do huge wrapping gouging roundhouse cutbacks with ultimate grip, or would you rather the tail spun more easily into a Taka? Size choice will also affect release.

LOOSENESS/CONTROL: Again a personal preference as to wether you like your board to feel loose and skatey, or more directional and planted.

SNAP/CARVE: Snap and pivot for tight 'in the pocket' surfing, or carve for more drawn out turns on open faces. This is related to looseness/control but more to do with template than flex.

LOW DRIVE/HIGH DRIVE: Your immediate thought might be that the more drive the better, right?! Not always the case. Quite often on multifin boards you'll find yourself flying up at the lip but without the ability to get the board turned, this is too much drive.

These ratings are to compare k4fins only.

K4 fins are a unique innovation in windsurfing. Simply put they are different.

K4 fins are all about phat twins, tri's and quads. The new technology isn't appropriate for the longer single fins. The K4 multi-fin shapes, design, and innovation has come from water time. Coupling this with science and know how has culminated to something ground breaking.

You know how sails 'breathe' and twist off to keep control and deliver speed? K4 Fins do the same to multi-fin wave boards by designing a flex pattern that works with you. K4 Fins have created a unique and new material for windsurfing. OptoFlex is a molded resin long fibre matrix that has been carefully manipulated to provide the perfect flex patterns for windsurfing. K4 technicians took a long time to create the perfect material with the qualities needed to provide the performance we now appreciate. Lighter, snappier and with outstanding flex memory.

When powering around the fins flex from the tip down. When Jumping and general sailing you feel the fins under the foot complimenting your movements. When heading up-wind you feel the fins flex and work with the power your putting through them. When landing they again flex and work with you, rather then against you!

Simply, the more energy you put into the initiation of a bottom/top turn the more performance the fins will then deliver back to you! The fins release the energy you put in at the exit of the turn in the form of a squirt of acceleration right where you want it!

Waveriding is where the fins really excel. In your bottom turn the flex of the fins allow you to drive them hard and fast. As you're going through the bottom turn and your speed starts to drop off the fins give you something back. All that 'stored' energy from the flex is given back to you when you need it most. In doing so you don't get stuck through your turn. You can power all the way through to the lip and smack it at full velocity. We think Graham Ezzy hits the nail on the head:"The flex allows me to go more vertical and hit later lips. Instead of getting stuck in the curl, I can push on top of it and get more projection. Super cool."

K4 fins  Summary:

• Turn harder with more grip and torque - onshore, sideshore, cross-off shore
• Track higher upwind
• Easy to initiate and control slides - But don't spin out!
• 'Whippy' lively feel that makes your board come alive!
• Deliver a squirt of acceleration right where you want it!

Check out this link to the K4 Fins website

Check out this K4 Fins Tuning Guide link

Check out photos of K4 Fins on Flickr

Check out this K4 Fins Selection Guide link

All fin lengths (cm)

All weights (g)

STANDARD K4 FLEX: Our fin for looseness and grip.

K4 STUBBIE:  Our fin for onshore grunt, tri fins or heavier riders.

K4 SHARK TOOTH: Our fronts for speed and looseness.

K4 TRI SIDES: Tri fronts for control and sweeping turns.

K4 FREESTYLE

BLANKERS

K4 FIN TUNING

As with many things in windsurfing, fin tuning ultimately comes down to your own personal preference, your board and the conditions you sail in. There is NO one right set up. With that in mind, here are our guidelines and some general rules.

SIZE SELECTION

SAILOR WEIGHT

• The lighter you are and the more fins your board has the more flex your fins should have. If we imagine both ends of the scale; a 55kg sailor sailing on a large quad board in good waves with a 4.5m sail in light winds, and a 95kg sailor sailing a 6m sail overpowered in chop on a small single fin board (or rear biased Tri fin), the difference in fin force is huge. The lighter sailor will need very flexible fins in order to get the most from his board and the heavy weight stiff fins to deal with the high loads. The more fins you have in your board the more the load is shared and the less force on each individual fin. Obviously the higher the load on a fin and the longer the fin, the more it will flex. Our shorter fins are designed to have more flex than the larger sizes.
• For the heavyweight riders of 90Kg plus we have brought out a range of stiffer fins, called the STUBBY.  Although we have many 90kg+ riders who love our FLEX fins, we realise that for use in gutless waves, chop and/or overpowered conditions some extra stiffness would be a good thing particularly with rear biased set-ups.

TRI FINS

• We've found that for Tri fin set ups in good waves, almost equal sized fins are best with K4fins (eg 13 sides and a 14 or 15 rear). This will help all the fins work together and give a 'quad' like feel, maximising looseness and turning ability. Any of our front fins can be used; the CARVE have more base area and sweep, giving better control and drive, the SHARK TOOTH fins will be looser and faster, and the STUBBY's will give more pivot and a direct feel.

QUAD FINS

• With Quad fin set ups you can tune your board to feel more 'twin' like with smaller fronts and larger rears (eg 6 or 8 fronts and 15 rear), a standard quad (eg 10 front and 14 rear) or even go with bigger fronts and smaller rears (13MT tri or 14 US rears in the front and 12 rears).
• A rear area bias will make your board feel looser, easier to redirect or change line mid turn and have better 'pivot' in your top turn. It will be more 'twin' like in feel and we would recommend this set up for onshore conditions where looseness and snappy turns are the main requirement.
• A standard quad set up will make the board feel drivier in the turns, much better for swooping cutbacks or power gouges. More grip and confidence in hollow or steep waves. The trade off is slightly more difficulty in changing your line once set, and top turns may feel less snappy.
• A front area bias will make the board easier to 'push' through turns and release the tail particularly when underpowered. You may find you lack speed and drive down the line with this set up though, so it's better suited to slow softer waves. You can get some nice 'hooky' top turns using the rail with this set up and can be good if you're not having to chase the critical section.

FIN POSITION

FIN TEMPLATE

• The outline of your fin makes a considerable difference to it's performance..
• A wider base will give better drive and acceleration.
• A narrower base more speed and pivot.
• A more upright fin with less 'sweep' will give tighter turns and more pivot.
• A more swept back fin will give better control and more sweeping wide arc turns.
• More area will give more hold but be stiffer for a given length.
• Fins with a longer tip out the back (or rake) will give more grip and direction, better for larger arcs and powerful carves.
• Fins with less tip will be more snappy and turn tighter, better for staying in the critical section of small waves.

FIN CARE

• To keep your K4fins looking clean and shiny it does them no harm at all to go in the dish washer every now and then. This is highly recommended.
• Minor nicks and scrapes can be easily sanded out with 240 or 400 wet and dry.

Check this link to see Windsurf International magazine indepth article on K4 Fins

Graham Ezzy on riding K4 Fins @ Jaws: "Last week on Maui the swell was lining up to be massive enough for Jaws to break. I was excited for the big waves but also a bit worried because the only fins I had were my new sets of K4 plastic fins. And while I loved the fins in smaller waves, I wasn't sure whether they would be too flexible for the big bottom turns at Jaws. Without too much thought, I threw in a pair of 15" back fins and 7" front fins on my quad board. I was the first windsurfer to ride a quad board at Jaws back in 2009, and last week I think I was the first windsurfer to ride plastic fins there. The best part was that the fins worked amazingly. I was able to push really hard in the bottom turns without anything close to a spinout. And I was even able to throw a big air. It was the first time K4 fins were used at Jaws but it most definitely won't be the last!

K4 fins  have been extensively tested in NZ at Pungarehu, Kina Rd, Waitara, The Ditch, Takapuna, Orewa, Omaha, Auckland harbour - and have delivered in all conditions! Also tested at JAWS...

Check out this link to a review in the Seabreeze forum

Heres an overlay of our three different templates for k4 14cm fins. Ive renamed the TRI the CARVE (as the STUBBY is also a good choice for Tri fin boards). The areas are given next to the names.

Notice the greater area and wider base of the CARVE -this gives it greater drive. The STUBBY has less rake giving it more pivot, and a stiffer tip giving more release. The FLEX is our original template and still great for most sailors with the ideal mix of grip and looseness.

The STUBBY is the stiffest fin, followed by the CARVE, with the FLEX being the flexiest. For more info on what this means to your fin choice, see the section on TUNING.

Heres an overlay of our smaller front fins, the ones youd use with bigger rears. The stubby with its greater area (67) and larger more swept tip will give more drive, hold and grip. The Shark tooth has a more efficient template for speed, whilst being super loose due to having less tip -a good choice if your rears are providing plenty of grip and drive.

U-Ride Quad Fin Test Results

CHECK OUT K4FINS KILLING IT IN THE U-RIDE QUAD TEST

(Perhaps K4 Fins should have sent an 8 or 10cm front to give us full marks!!)

Google translation&.

K4 FOR 14 & 6 www.k4fins.com

Developed in England by Steve Thorp and taking advantage of a technology choice that could raise a smile at first, has K4Fins surprise and seduce since its inception in 2010.

Built in injected plastic, the K4 offer for a surface in the middle for the rear as in front. The weight is unbeatable on making it a major advantage in quad configuration compared to all G10 that increase a little the rear boards.

ON THE WATER

We find immediately the feeling that we K4Fins had not escaped in 2010 in our tests and twin models that carcatérise one word: flexibility! The planing is good but the feel is different from that of G10 fins. Flexibility more important than the G10 slightly delayed perception of the departure schedule and we must adapt the technique to quickly take off the board.

In the navigation K4 Fins are quick and very pleasant underfoot with good support on all speeds. Navigation is very seine and not surprisingly, with a very good glide and support without excess. Navigation is free, only in conditions very overpowered flexibility imposes some possibilities stall if the support on the back foot is excessive.

Surfing the set K4Fins is particularly efficient and pleasant change of support. The lines are sharp, the grip is very good and we feel that greater flexibility than conventional fins provides support change very fast and accurate while providing a very soft feeling.

In Conclusion K4 Fins offers a real alternative to G10 fins with plastic fins. These fins will satisfy the most demanding surfers with fins fast, accurate and do not have to blush against the best fins on the market! It is our heart of this test.

The pros: weight, flexibility and overall performance
The -: adapting its support for planing

K4 Fins "Bubble" Pro Freestyle

Andy 'Bubble' Chambers talks about the K4 Freestyle fin design and development process: http://www.k540.com/?p=283

"I got in contact with K4 Fins about possibly making a freestyle fin. It was new territory for both of us as we didnt know how the material would work for freestyle. The great thing with Steve from K4 is that he actually listens to everything you say! So we came up with a couple of shapes and Steve moulded them up super quick! It was also the windiest week in the UK so far so perfect for testing the shapes! I tested them in my new secret freestyle spot so i got the chance to test them in all sorts of chop and flat water.

The first thing i noticed was that i couldnt feel any difference between the plastic ones and the G10 ones! Which meant we had a great opportunity to change and play around with the shape to get the ultimate freestyle fin. The other main things to consider are the weight and the cost which are both a lot less than normal G10 fins! I took the prototypes straight to the UKWA Freestyle event in Minis bay and won the event using them! I have that much confidence them. 

My results in the UK Waves and Freestyle so far this year have been directly attributed to K4 fins and Im feeling super stoked to be a part of the team. A brand made by windsurfers for windsurfers who listen and innovative and are just hell keen on getting out on the water and going sailing pushing the limits of themselves and their equipment to the max!

I am taking the fins on to the World Tour for the whole year!"

Check out this video of K4 Team Rider Andy 'Bubble' Chambers talking about his new K4 Freestyle Fin. Packed with Windsurfing Freestyle Action of Andy on tour utilising his new K4 Freestyle fin. Andy and the K4 design department have been working hard to bring out the best freestyle fin on the market. The New K4 Freestyle fin is setting a new standard in Freestyle Fin performance.

Video of K4 Team Rider Andy 'Bubble' Chambers talking about his new K4 Freestyle Fin.

http://vimeo.com/32082778

K4 Fins 18cm - 16cm - 14cm Stubbies:

Our stiffer and larger area range of fins. Great for heavier riders applying greater power in higher winds and wanting more drive in lower winds. Also great for lighter riders in onshore conditions or those wanting more 'release' to learn Takas and other new school freestyle/wave moves. Upright template gives better pivot for in the pocket syle riding.

Flex: Low