Getting the bottom contours I wanted keeping the intended rocker, within the limitations of HWS was a chin scratcher for sure. So much easier to have flat to a subtle V off the tail with HWS, but I really liked the deeper concave under the front foot on a friend's similar foam board with appropriate volume that I tried one day when i was still pre pen on paper building the board in my mind. I wanted a new short board which had to be worked a bit more, not just a step forward and trim it out as I sometimes did with previous HWS that had very subtle bottom contours especially when it was ridden as a 2+1.
Bottom coutours turned out about 90% as i intended. Making HWS in the manner I do, will always try and form some concave closer to outline's apex and flatten out the rocker, and I intended to fight this tendency at every stage of the build no matter the extra time and labor and material involved. I was mostly sucessful, but proper lighting and a straight edge would easily reveal deficiencies to the trained eye. Mainly that the concave under the front foot is not a smooth arc but a bit more curve closer to the rail and a bit less through the middle, and not quite symmetrical. I could not safely shape it out without going too thin under center stringer, and that would have been a lot more than 1/4" concave, which I did not want. Perhaps this 'deeper rail' under the front foot and the sharky rail fins are both responsible for the overrotation when I lay it hard on rail.
So many HWS I see, seem to have that weird bump in the outline and rocker where the rails join nose and tail blocks. The way I form my rails helps to eliminate a fair amount of this wonky tendency, but is a lot of work and requires a lot more fairly expensive clear grades of wood. I've had it eyeballed by a few experienced shapers and glassers who assumed it was a uniquely veneered Compsand until they saw the nose vent, then felt the weight, but none of them thought it was a Kit, or was obviously a HWS, on appearance alone. Most HWS I can spot from quite a distance away due to rather primitive looking rockers, and wonky outlines in the nose. I suspect most board builders can, and am glad my board is only obviously a HWS by the thumbscrew in the nose, and when underarm, the weight. I never think it feels too heavy underfoot, only underarm.
When I unscrew the vent in the nose, to let the board suck in air in the lineup , many people always ask WTF I am doing... and had No idea the board is hollow. Which makes me happy. They also tend to give me way more space after, which makes me happier.
Still experimenting with untraditional fin designs in this board.
Since the smaller sharky cedar rail fins and Mr Mik's cut down 0.45GW center fin was way too loose, allowing hyper twitchy overrotation when pushing hard, I tried those same rail fins with a 0.5GW fin, whose Probox tab is about 1/2 inch farther forward on the fin, allowing the fin to move 1/2" farther back in the board. It is also raked back slightly more than the 0.45GW fin and slightly deeper. This made a huge difference in reducing the hyper twitchy overrotating feel when pushing harder, and I was having a lot of fun learning to enjoy this combo, in some pretty good groundswell.
Unfortunately, I lost one of these 0.5 GW fins. I had originally made these to accept the grub screws for being rail fins, with flats for grub screws on one side of the tab, and did not make a recess flat on it for being a center fin with opposing grub screws. I just torqued the opposing grub screw into the Fin and said good enough to try. It was not. That fin is now gone.
1/4 the way through a hard backside bottom turn, I fell flat on my butt like all three fins sheared off, but on retreival, only the center fin was gone, to my relief. I have the other 'rail' 0.5 GW fin as a backup, and that fin now has grub screw flats on opposing sides which should not allow the fin to eject so easily from the center probox. I do suspect my leash had partially ripped the fin out on a previous ride... the turbucles not only catch grass and kelp, but leashes too. I caught one wave with the board as a twin fin with these smaller sharky cedar rail fins. It was a 18+ second period swell, well overhead set wave, courtesy of the Southern hemisphere, that closed out, but only after I made It a good distance, being reminded how twin fins are just so incredibly speedy on open face. As a twin with these sharky fins with no raked tip, there was zero stability which made for a scary late drop, but which earned a bunch of hoots.
The next day I put a Wavegrinder fin in the center probox, the larger stiff version in cleaner similar conditions. A long period strong swell largely walled with some select corners available. The WG fins had previously imprinted on me a tracking feeling whether the full size WG2 in my longboard or the smaller WG fin as quad or thruster center fins in this board. I thought it might work well with the super pivotal and loose sharky rail twin fins. I was wrong. These Wavegrinder fins are also super high aspect ratio, and have the winglet on the top. This wavegrinder fin with the smaller sharky cedar twins felt atrocious, Slow and unresponsive and dull, as if the leash was wrapped around the fin, but it was not. Obviously the winglet and my board's tail rocker did not agree. One wave when I was up higher in the face, it felt good and responsive, briefly, but anywhere outside this part of every wave, and it felt like a sea anchor and I blew a few good waves because of it. I had the other 0.5GW fin in my pocket, with a fin key, but the pocket's Zipper head came clean off in my fingers after removing just the key, and would then balloon up afterwards, had I ripped the fin from the pocket, swapped fins and kept riding. I considered kicking out the WG fin, breaking off its tabs, riding the board as a pure twin, as it felt so horrible. I did not and this WG fin ruined my session, then the wind came up before I could get the 0.5GW fin in the board and paddle back out.
Anybody want to buy some larger WG fins, the 5.7 inch deep ones? I have lent out the 4.8's a while back and not seen the guy since. I would have used the 4.8 had i had it. It was Ok with more traditional shaped thruster style rail fins.
These High aspect ratio sharky or turbucled fins are a trip. These are an extreme experiment, in high aspect ratio in multifin boards, but for being large deep fins that look so untraditional and just wrong, they have noticeably and undeniably less drag than smaller more traditional dol-fins shapes. They also allow for a much tighter turning radius, to an almost ridiculous knee collapsing degree. They are super quick, super loose, with a lack of self centering and stability, compared to a more traditionally shaped fin. I wonder what a more youthful rubberkneed surfer could do with more speed and a tighter turning radius should they get over their untraditional look, and try them.
Why do all multifins need to perform the same tasks of adding stability and self centering? ...and thus be the same general shape and size.
They obviously work and work well, but How much self centering and stability do all the fins need to have? Seems to me other than being traditionally visually acceptable, this is the only benefit from the raked tip, at the expense of added drag and resistance to turning.
Well, shedding grass kelp and leashes is certainly a benefit of more traditional fin shapes, Can't deny that large factor, but from a tight turning radius, and low drag perspective, high aspect ratio is a different level, a much different feel, and I am digging it. I can still draw out the turns, but I can push harder and reduce that turning radius too with higher aspect, I don't necessarily need the fins raked tips limiting the turning radius or adding stability and drag, not all three of them anyway.
The purple turbucled fin in the pic below is a cut down version of Mr Mik's 3d printed Albatross Whale fin, which was a more extreme version of his Gullwhale fin, now just called the G-Whale fin. I made a mistake in the location of the probox tab, I want the fin farther back, but will try it like this first before modifying the tab to allow for a more rearward position in the board.
The larger sharky twin fin, that I retained after the collision, and which was broken,( the other lost) has been resurrected. It is on my port rail, for going left. Its trailing edge grew with the extra thickness from the extra glass used to rebuild it. It is ridiculously stiff. Hard to imagine water pressure alone deflecting the tip more than a few mm.
I also modified one of Mr Mik's large single red Deaweeder fins to fit Probox center tab with no fore aft adjustment. This fin's filament had issues with interlayer adhesion, and was quite flexible in my singlefin longboard box, before I added 2 layers of 1.43 oz cloth up the sides of it. That fin is not quite ready to go yet, and none of these modified fins of Mr Mik's designs, have been made to fit probox perfectly, yet.
Getting the grub screw bottoms to rest perfectly on flats on the fin tab, is yielding fin tab receptacles much different than any factory FCS1 fin I have. The receptacles are higher, deeper, at a different angle based on trial and error fitting and seeing where the grub screw threads dig in. While simple fin retention is easy enough to achieve via finkey torque alone, I want the whole fin to fit tightly in the receptacle, with no wobble, and the grub screws flattened bottoms resting on a perfectly angled receptacle on the fin tab. Should be easy to achieve this, yet it isnt. I've been achieving an 'just OK' fit so far, before going further towards ideal if the fin rides well, the going further part has not been followed through on yet, despite the 0.5GW being a good performer.
I have a whole other fin panel ready to cut into, to make new rail fins. The latest cardboard fin template I made is based on the larger sharky twin, but is slightly lower aspect ratio with a slightly more raked tip, but nowhere near traditional fin designs. I need to see how the larger rebuilt sharky twin goes left , before backing off these weird looking high aspect ratio sharky fins and working my way towards the middle ground compromise. I am thinking my happy middle ground will be much sharkier looking, than dol-fin looking, but time will tell, and I'll enjoy the experimentation.
Edit/Add.... as i don't want to bump up the thread, just to add the following:
The Purple 0.5 AW fin was not feeling right in the center box in two different sessions with the larger rebuilt sharky cedar fin on my backhand rail. The overrotation when pushed hard was as bad as the 0.45GW, which makes sense as their trailing edges line up when pushed all the way back in the center Probox. The extra depth of the purple fin does not make up for the loss of width. I intend to try it again once I move the tab 1/2+ inch plus farther forward on the fin allowing it to be that much further back in the board. In point and shoot speed on mode, not turning hard, it was certainly quick and responsive, but on light turns with the board flatter in the water the whole board would arc around on the inside rail fin as if there was no center fin and there is more toe-in than there actually is. It was a bizarre feeling and reminded me of how the full size turbucled Albatross whale fin felt in my traditional 9'7" log.
I have modified the yellow 0.45GW fin to overhang the box over a half an inch farther, but not yet tried it. I have also gotten the red 0.5 Deaweeder fin base to fit nicely, and be strong enough, and rode it today for the first time today with both smaller sharky cedar fins, and it felt really good, really responsive. 3 of my rides felt rather incredible from a speed and maneuverability/turning radius factor and the top turns and carves i pulled off, but as I gained more confidence in this fin cluster, I was able to overpower the fins on 2 frontside bottom turns which felt awkward. I would not say overrotation like the board was turning too tightly, buckling my knees, but more like the tail was drifting when pushed that hard and shortened the turning radius by 'pulling the parking brake' instead.
The modified red DW fin also got some carbon rods and SS screws up into fin through fin base and the grub screws press either onto a carbon rod or SS screw. No fore aft adjustment, the tab is the full width of probox receptacle right now. I did not sand the epoxy 'fill' coats near to the best of my ability pre surf today, a bit rushed, figuring I would do that if I decided I liked the fin. I do like the fin, and yet it was nearly continuously humming on each and every wave, and hummed loudest on those bottom turns just before the tail started drifting towards shore. Gonna go fine tune this fin now and hope the swell holds as this is a good combo despite being able to overpower them on some frontside bottom turns. Never before have I had a fin humm for so much of the ride.
The next rail fin template is still being contemplated. Same general surface area and depth, but tabs farther forward on fins and with a smidge more rake. Kind of wishing I installed the proboxes further back in the board, but i was not familiar with high aspect ratio fins when I laid those plans.
The rebuilt and slightly larger/thicker sharky cedar fin on my backhand rail with purple center fin, felt like too much fin in parts of the left, like it was locked in a track despite the happy go lucky nature of turbucle center fins in a partial stall. I liked this fin template best with the 0.45 GW fin whose first turbucle overhung the front of the probox, but that 0.45 gw fin is now modified to sit further back on the board.
This rebuilt sharky cedar fin is slightly larger and thicker, and while quite stiff before it partially broke, is much stiffer now, and seems to have lost that feel it once had. I think while the smaller sharky cedar fins template is just too upright, that their depth and size/surface area is in the ballpark for a rail fin in this board.
Might have to try replacing the 8 degree insert with the 6 degree on my frontside rail, see if the smaller sharky twin then holds a bit better on those hard frontside bottom turns with a properly located back foot. All these sharky cedar fins have some extra cant built into the fin tab, although I have not measured it precisely. Its likely around 11 degrees total with 8 degree Probox inserts.
I fine tuned the trailing edge of red 0.5 deaweeder fin, and it was silent on the next session. In dying swell, the board was very solid again, but I got no chances to see if I could overpower this fin combo on a hard frontside bottom turn, and have been riding my log since.
I wound up making a new Cedar zero clearance Insert for the surface of my Makita tablesaw. I have a taller longer fence with some more bracing to keep it perpindicular to the table, parallel with blade. The flat side of the latest rail fins I foiled, could slide perfectly along the fence, the fin base held on the new zero clearance insert, the blade height tuned exactly.
I'm all about a good footbone to finbone connection, and less than perfect fitting fins always bothered me, but so did failing when seeking something much nearer perfection
The tabs of my previous probox fins have been tapered as they ALL have been sanded to fit, and this taper would reduce total cant when grub screws were tightened. I was not getting 8 degrees of cant from 8 degree inserts previously.
These latest fins the tabs are the full length of the probox insert.
The thick portion of the foil sticking outside the width of the fin tab, is also angled at 8 degrees, with a razor blade after the pass on the tablesaw. The thick overhanging part of the foil rests almost perfectly flat, on the flat of the 8* insert.
I have never gotten any fin to fit any fin box as tightly as these new fins fit these 8 degree inserts. Removing insert from fin is difficult and time consuming, it can only be inserted or removed straight on or off, no rocking. There is Zero play for fore aft adjustment, though I can add that option later. Their trailing edges are 12 5/8" from the tail.
The white 8 degree inserts never fit the receptacles nearly as well as the 6 degree black inserts did. But now they do after time spent with a razor blade, scraping selected surfaces.
The fins below are the latest sharkyHAR rail fins, version 3.0 .
They are 6 1/8" / 155.575 mm deep
They have a 4 inch / 101.9 mm base
The Port fin is 0.386inch / 9.8mm thick at the base
The Starboard fin is 0.373 inches / 9.48mm thick
I've no idea how many square inches they are, and I am not quite sure how to measure aspect ratio, but needless to say they are very high aspect ratio.
They are very stiff, but have more flex than sharkyhars 1.0 and 2.0. and more of that near the tip.
This fin panel was made with 3 layers of 24 oz woven roving, Laid one at a time atop waxed heated glass, well saturated with heated epoxy rolled with a bubble roller, then warmed pre saturated 3/8" thick 3.5 wide western red cedar planks were laid atop and weighted. The heat was hoping for better saturation and more transparency.
Oh well. Its stiff and strong. Next time.
After foiling, two layers of 7.5oz or thicker old mystery cloth was laid atop, over the thick part and down teh side of the tabs. then two thick fill coats. Then refoiled the fin, wetsanded the fins to 800, and used some cheap spray laquer as a temporary gloss coat. Clarity issues with this old cloth. Oh well, next time.
The center fin is the 0.45GW fin, whose tab has been moved 9/16" further forward on the fin.
On a side note, the 0.5GW fin that I lost on a backside bottom turn about 5 weeks ago, on a fairly big day at low tide, has found its way back to me. Whomever found it, where and when is unknown. Also unknown is how long it was left on that fencepost, at the top of the trail, anywhere from 2 minutes to 6 days. I expect if it had a futures or fcs 1 or 2 base it would have been snagged by a passing surfer, but perhaps not, perhaps it is too weird.
I know the 0.45GW fin was very good with sharkyhar 1.0 when further forward in the probox.
I am excited to ride sharkyhar3.0 at 8 degrees cant, and 0.45GW version 2 in the center.
The purple turbucled 0.5AW fin is in the process of tab extension and might be ready the next time set waves are chest high +.
I know the red 0.5 deaweeder can always tame the turning radius, if required. It did not seem to add much drag either.
These latest sharky cedar rail fins I made recently, which I now call SharkyHAR version 3.0, have been impressive, and more so with more sessions accumulated on them.
With the 0.5GW yellow turbucled fin as shown immediately above, the board was feeling a bit too loose with a too short a turning radius, but with the red 0.5 DW fin in the center box shown further above, it feels incredible, and each session thereafter, it has felt even better.
I've gotten a front foot traction pad, placed over the rail fins and not far behind them, not for traction, but as a back foot location indicator I can feel without looking. With so much singlefin traditional longboarding in my background and present, I tend to have a wild back foot placement when I get back on a shortboard, so the location indicator traction pad saves some time readjusting, getting over the longboard hangover, and knowing the back foot is in the right spot before initiating a turn.
These latest sharkyhar rail fins, whose tab location has them located farther back on the board, make the sweet spot smaller and significantly sweeter, but less forgiving for back foot placement in front of that area. Back foot behind the traction pad, and my stance feels too wide and unnatural and the board way too loose, but better too far back than too far forward.
What really strikes me about these sharkyhar3.0 fins is the accelleration on open face above the trough. Late drops at an angle on a long lined up wall, it's like the board does not really want, or need, to go to the trough, but instead is more than happy to turn mid face and simply start rocketing parallel to shore and inducing speed to then possibly burn. Standard 'dol'fins would have to be forced to do this, yet would likely stall and slide and drag, where these seem to initiate it this mid face turn, but they hold and project Which has been nothing but beneficial in the location and conditions I have been out in.
One observer said it looked 'unnatural' at just how fast I gained speed on the drop, and this was while I was still getting my back foot in the right spot and my stance neutral. When I did, and was then actively seeking more speed on this barely head high wave as it stretched out, it was easily the fastest I have gone on this board on that size of wave, approaching the max speed attained on the biggest waves I have ridden on it, at double that size with a much longer period. Honestly, this mid face accelleration parallel to shore is difficult to get used to the first few rides of a session. I never quite seem to be fully ready for it and am off slightly balance, and as more of a front footed surfer, I've been forced onto the backfoot those first few rides each session and a little out of sorts. When I do get used to it enough to anticipate it, it seems the swell is fading quick, and I am back on a longboard until it rises again and then have to relearn it.
I know dedicated twin fins, with or without a smaller trailer fin that I have ridden in the past, they have always been most responsive well above the trough, and would require I take different lines requiring that I almost completely avoid the trough. Which led to me not riding twin fins anymore as I really like laying a well timed hard bottom turn in the trough, and a board which does not allow that is not a board I want, no matter how quick it might be above the trough. This board with these SH3.0 rail fins and 0.5DW is not afraid of the trough like a dedicated twin fin from my past, it just has that twin fin speedy reward on open face above the trough. Speed of a twin but the solid feel of a thruster through turns anywhere I have yet chosen to place them. Seems to be a win win at this point. It's certainly not an overfinned feel, not even close, yet total surface area of these 3 fins is likely well above that of a standard large thruster set. Overfinned usually feels draggy and stiff, yet these are quick and loose.
The speed reward for open face pumping with my back foot in the right spot on that one wave, was so far beyond any other fin set up in this board, or pretty much any board in my memory. It is not really the 'squirt' one expects from a round pin, a big wide board with wings or not. The wave eventually ran off, forced me to straighten out and ditch, but when I retreived my board and started paddling back out, looked back to shore at my lineups and where the guy I was sitting 15 yards deeper than was, noticed the distance I covered in such a short time, I was like "holy F***!!". It took me forever to paddle back and the guy was like: 'What crazy looking fins are you riding today?'
Almost every backhand wave, when I bottom turn before reaching the trough, I am surprised with the accelleration.
On another wave that day, the same observer guy remarked how I completely 'tore the top off the wave' on a backside top turn, and indeed it did feel incredible, yet I was not really going all that fast when I squared off the bottom and entered it. It just felt right, felt good, really good, and to have someone else compliment it made it even better.
I've not gotten too many frontside waves (rights) with this fin set up yet, but the traction pad now shows me just how much farther forward my foot back lands on pop up frontside compared to backside, which has been enlightening. I've gotten few rights with this specific fin set up, a few which felt great when my back foot was located correctly, some less so, and one or two weaker smaller waves in which I was like WTF is going on down under there?, usually as I was exiting the wave.
I rode some of the smallest weakest waves I've yet ridden on this board today, and again was amazed with the speed so easily attained on open face. The get up and go is simply unreal with these fins. The responsiveness to input is unreal. There's seemingly no delay, and this is a 15.5 lb board. I've been surfing rarely too, once or twice a week at most the last few weeks, and more longboard than short, as I can't handle the summertime warm water hyper entitled and oblivious crowd mentality, and the few swells to arrive have been mostly weak and inconsistent and overforecast.
I'm a tinker by nature, but I'm at a loss as to what I would now want this board to do differently underfoot, at least in the conditions/locations I have so far ridden it in with this fin combination. Perhaps in other conditions/locations I would want the fins to force me to draw out turns, or add some self centering stability, but honestly, I am excited to ride this board in conditions I'd formerly never consider taking anything but my longboard out in, and can't wait to try it in some size and power. If it needs more stability or a drawn out turning radius in more powerful conditions, I will add it via the center fin, whether a larger fin and or a more rearward placement of it, but if these Sh3.0 rail fins got unknowingly superglued in place, I would likely not notice for a long time.
I have made a drilling jig and added two more grub screws to my center probox. I used SS 5mm grub screws with a finer pitch than the standard 10-24 grub screw. I had them on hand thanks to MrMik, and my existing sharp drill bits matched better to the metric tap.
The probox inserts for rail fins have been having me questioning the location and angles of additional grub screws for them. The ideal jig for additional grub screw for an 8 degree insert, and the flat spot on fin base for the grub screw receptacle, will be slightly different than that for a 6 degree insert. I've not yet tried the sharkyhar 3.0's with 6 degree inserts and honestly see no need to change anything at this point, but when I made the center jig I was less sure of Sharkyhar3.0's potential and decided to hold off on the rail fin drilling jig.
I have a lot of fin panel left, but no desire to make more fins at this point, mostly as I have no idea what I would want to change about the way these rail fins have performed in this board. At this point I am just eager for more swell and less crowds, and to ride this board with these fins even, in conditions I normally would not consider anything but a longboard.