Over the past couple of years with the introduction of multi fin wave boards (mostly referring to quads and thrusters here) one thing that I have found pretty frustrating is how ridiculously over finned they are. The production boards are supplied with fins that are massive. They work ok in rubbish onshore jumping conditions, where early planing and upwind ability is a priority but in down the line conditions these fins really hamper the turning ability and loose feel of what are otherwise excellent shapes.
I personally use JP quads which are supplied with 10cm side fins + rear fins that are the same size as what I would use as a twin. Fanatics etc. all have similar sized fin setups. There is simply too much fin area. Changing down to 9cm sides with 13cm rears (the smallest JP make) it improved the board's turning especially in small waves where it felt a bit too stiff. The difference was promising. Others who have tried using smaller fins in their quads have all found the same thing - the waveriding ability is increased substantially with little loss in all round performance. However my verdict still remained the same - quads felt stiff in small waves from head high and smaller. The G10 fins provided little flex and were not forgiving through the turns, something that is needed when you have little time between bottom and top turning (ie. Small waves).
When I heard about K4 fins I was interested - flexy fins made out of plastic supposedly improving your boards turning ability with the added benefits of being substantially lighter and cheaper than G10 - but I wasn't entirely convinced. They could be too soft and spongy, losing out on speed, early planing and upwind performance. After getting my hands on some in 12, 13, 14cms and 6, 8cm side fins I have now got them out in some decent conditions and say that none of those concerns were justified. At first glance the fins were a pretty standard shape with slightly more area compared to the JP's of the same length. However the difference between the stiff G10 and flexy K4s was massive. My session on the fins was in gusty 15-25 knots cross off with logo high sets, testing the 8cm and 13cm combo. After two or three waves I was absolutely blown away at the difference the K4s made.
The first difference is noticeable as you come through your bottom turn. The flex in the fins is very apparent and as you are finishing the turn the flex 'whips' you out of the turn with an extra burst of speed that you do not get with G10. Suddenly you have more speed racing back up the face for the top turn - where the flex is the most beneficial. The K4's give control, speed and manoeuvrability through the top turn, allowing the board to rip around on the rail into full on roundhouse gouges or to push hard and chuck buckets with little chance of sliding out uncontrollably. The flex also helps when you are late hitting a section allowing you to go vertical and then come down with the lip in control. In these situations G10 fins can often spin out when the force of the wave smacks you back down into the flats. The K4s absorb the energy of the wave and allow you to sail out of turns you probably wouldn't have made with stiffer fins.
When sailing in a straight line fully powered the fins provide a pretty interesting sensation. It feels like the flex in the fins provides lift and the board feels like it hovers slightly higher out of the water than with stock G10. I found that this means you can load up the fins and crank upwind, they can slide out occasionally but it definitely feels different to G10, recovering easier.
Using the K4's so far I have only found one real downside - in choppy onshore conditions when backside waveriding is a priority, the flex can be too much. However these fins are not designed for these conditions and going up a bit in fin size overcomes this issue. Apart from that I've found these fins offer a whole lot of benefits for wavesailing, especially in down the line, clean waves.
I'm sure these fins do have limits - at a certain size the flex will become too much so they are only appropriate for multi fin boards using small fins under 17cm or so. Heavy weights may also find them too flexy for their weight in the larger sized fins that they would typically use but I believe K4 is about to release some stiffer fins to address this anyway.
For those with quads I would definitely suggest giving them a go. For those with hugely over finned thrusters (such as the JP - supplied centre fin is easily big enough to use as a single without 2x 10cm side fins) it would be worth experimenting with smaller fins all of a similar size eg. 16cm rear and 13cm front. I haven't personally tried it but have heard good things about improving the down the line performance of thrusters.
Summary:
Good:
Lighter than G10
Cheaper than G10
Better range and control due to flex.
More grip, speed and manoeuvrability on the wave in down the line conditions.
Bad:
Possibly limited to smaller sizes so only suitable for multi fin setups.
Loses drive with the flex through backside bottom turns in onshore.
Some heavy weights may find them too flexible.
Trying the 6cm and 13cm combo in tiny crappy waves today.
 | This image has been resized to fit - click to view as 1200x864. |
I personally use JP quads which are supplied with 10cm side fins + rear fins that are the same size as what I would use as a twin. Fanatics etc. all have similar sized fin setups. There is simply too much fin area. Changing down to 9cm sides with 13cm rears (the smallest JP make) it improved the board's turning especially in small waves where it felt a bit too stiff. The difference was promising. Others who have tried using smaller fins in their quads have all found the same thing - the waveriding ability is increased substantially with little loss in all round performance. However my verdict still remained the same - quads felt stiff in small waves from head high and smaller. The G10 fins provided little flex and were not forgiving through the turns, something that is needed when you have little time between bottom and top turning (ie. Small waves).
| This image has been resized to fit - click to view as 2156x670. |
| This image has been resized to fit - click to view as 1200x742. |
When I heard about K4 fins I was interested - flexy fins made out of plastic supposedly improving your boards turning ability with the added benefits of being substantially lighter and cheaper than G10 - but I wasn't entirely convinced. They could be too soft and spongy, losing out on speed, early planing and upwind performance. After getting my hands on some in 12, 13, 14cms and 6, 8cm side fins I have now got them out in some decent conditions and say that none of those concerns were justified. At first glance the fins were a pretty standard shape with slightly more area compared to the JP's of the same length. However the difference between the stiff G10 and flexy K4s was massive. My session on the fins was in gusty 15-25 knots cross off with logo high sets, testing the 8cm and 13cm combo. After two or three waves I was absolutely blown away at the difference the K4s made.
| This image has been resized to fit - click to view as 2029x938. |
The first difference is noticeable as you come through your bottom turn. The flex in the fins is very apparent and as you are finishing the turn the flex 'whips' you out of the turn with an extra burst of speed that you do not get with G10. Suddenly you have more speed racing back up the face for the top turn - where the flex is the most beneficial. The K4's give control, speed and manoeuvrability through the top turn, allowing the board to rip around on the rail into full on roundhouse gouges or to push hard and chuck buckets with little chance of sliding out uncontrollably. The flex also helps when you are late hitting a section allowing you to go vertical and then come down with the lip in control. In these situations G10 fins can often spin out when the force of the wave smacks you back down into the flats. The K4s absorb the energy of the wave and allow you to sail out of turns you probably wouldn't have made with stiffer fins.
When sailing in a straight line fully powered the fins provide a pretty interesting sensation. It feels like the flex in the fins provides lift and the board feels like it hovers slightly higher out of the water than with stock G10. I found that this means you can load up the fins and crank upwind, they can slide out occasionally but it definitely feels different to G10, recovering easier.
Using the K4's so far I have only found one real downside - in choppy onshore conditions when backside waveriding is a priority, the flex can be too much. However these fins are not designed for these conditions and going up a bit in fin size overcomes this issue. Apart from that I've found these fins offer a whole lot of benefits for wavesailing, especially in down the line, clean waves.
I'm sure these fins do have limits - at a certain size the flex will become too much so they are only appropriate for multi fin boards using small fins under 17cm or so. Heavy weights may also find them too flexy for their weight in the larger sized fins that they would typically use but I believe K4 is about to release some stiffer fins to address this anyway.
For those with quads I would definitely suggest giving them a go. For those with hugely over finned thrusters (such as the JP - supplied centre fin is easily big enough to use as a single without 2x 10cm side fins) it would be worth experimenting with smaller fins all of a similar size eg. 16cm rear and 13cm front. I haven't personally tried it but have heard good things about improving the down the line performance of thrusters.
Summary:
Good:
Lighter than G10
Cheaper than G10
Better range and control due to flex.
More grip, speed and manoeuvrability on the wave in down the line conditions.
Bad:
Possibly limited to smaller sizes so only suitable for multi fin setups.
Loses drive with the flex through backside bottom turns in onshore.
Some heavy weights may find them too flexible.
Trying the 6cm and 13cm combo in tiny crappy waves today.
http://www.seabreeze.com.au/forums/Windsurfing/Review/Flexy-fins-K4-fins-review/
Interesting review as I have a very similar experience and have been extensively testing K-4 twin fins (17-16-15cm) across-the-ditch in NZ for 12 months. 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 really 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 front side the fins will load up but then release off the top turn far easier than G10 fins which makes tricky clew-first front side riding easier as the top turn is faster and tighter in onshore winds so you get get through the turn without dealing with that surge of rig power on the back hand. Also in onshore backside riding they 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.
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!
For more info check out my K4 Fins Blog:
http://www.boardzone.co.nz/k4-windsurfing-fins-blog-xidc87430.html
Interesting review as I have a very similar experience and have been extensively testing K-4 twin fins (17-16-15cm) across-the-ditch in NZ for 12 months. 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 really 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 front side the fins will load up but then release off the top turn far easier than G10 fins which makes tricky clew-first front side riding easier as the top turn is faster and tighter in onshore winds so you get get through the turn without dealing with that surge of rig power on the back hand. Also in onshore backside riding they 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.
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!
For more info check out my K4 Fins Blog:
http://www.boardzone.co.nz/k4-windsurfing-fins-blog-xidc87430.html
K4 Windsurfing Fins Blog...
I have been testing the fins over the last six months and have the following feedback:
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!
Check out this link to the Boardseeker.com review of K-4 Fins: " K4 fins provide very good grip with a really nice balance between drive and looseness off the top. They will make your board livelier, yet more controllable. Theyre perfect for any wavesailor whos focused on waveriding, and the pricing is as impressive as the performance."
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!"
