Yeah, I got that. I always get confused because I call "gap" the latitudinal (parallel to stringer) distance between fins.
To get .5" gap I'm going to have to make some new fins. Might be worth a try.
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A twinzer, a thruster and a bonzer walked into a (sand) bar..
- Thread starter One-Off
- Start date
To get .5" gap I'm going to have to make some new fins. Might be worth a try.
The reason for the LERT sounds like a vortex generator. I remember going down the multi-vortex generator (MVG) rabbit hole.The reduction of the size of the fillet had more to do with vortex drag, the movement of fluid over the end of a wing section. In the case of keels and fins, where the end meets the hull/bottom , we're talking about the lack of this movement. The more perpendicular the joint the more efficient (less movement away from direct fore aft). The bigger the fillet, the more easily the airflow can deflect. This effect I believe would hold regardless of whether the hull is planing or not. In fact at planing speeds it might be more apparent. You see old boats and planes having big fillets (which are aesthtiically pleasing) which I think was more a nod to structural intergrity, but modern ones do not. Whether or not this can even be felt on a surfboard I don't know, but I kind of doubt it. If I recall correctly GG was adamant about the inferiority of glassed on fins.
I like glass ons, eg. I would never uses boxes for the runners.
In a complete different but realted topic, while googling to find a scholarly article on interference drag of sailbnoat appendages I came across this- LEX- leading edge extensions. Or more specifically LERT - leading edge root extensions. The concept sounds similar to the canard theory. I do not recollect anyone doing something like this with surfboard fins but I could be wrong.
How does the use of Leading Edge Root Extension help in increasing stall angle?
Leading Edge Root Extensions were first used in Northrop F-5A/B Freedom Fighter, which first flew in 1959. After that, many fighter air-crafts have used it, some of which are mentioned after the qu...aviation.stackexchange.com
In hindsight, I wish I picked a master's thesis on this topic, rather than getting into kelp forests. When I was an undergrad, George Lauder, who studied fish fins, was across the hallway from the prof that I worked for. Then in grad school, there was another fish physiologist, who studied thunniform locomotion. She was on my thesis committee, but I probably should've studied MVGs and finlets w/ her, instead.
Thanks.The reduction of the size of the fillet had more to do with vortex drag, the movement of fluid over the end of a wing section. In the case of keels and fins, where the end meets the hull/bottom , we're talking about the lack of this movement. The more perpendicular the joint the more efficient (less movement away from direct fore aft). The bigger the fillet, the more easily the airflow can deflect. This effect I believe would hold regardless of whether the hull is planing or not. In fact at planing speeds it might be more apparent. You see old boats and planes having big fillets (which are aesthtiically pleasing) which I think was more a nod to structural intergrity, but modern ones do not. Whether or not this can even be felt on a surfboard I don't know, but I kind of doubt it. If I recall correctly GG was adamant about the inferiority of glassed on fins.
I like glass ons, eg. I would never uses boxes for the runners.
In a complete different but realted topic, while googling to find a scholarly article on interference drag of sailbnoat appendages I came across this- LEX- leading edge extensions. Or more specifically LERT - leading edge root extensions. The concept sounds similar to the canard theory. I do not recollect anyone doing something like this with surfboard fins but I could be wrong.
How does the use of Leading Edge Root Extension help in increasing stall angle?
Leading Edge Root Extensions were first used in Northrop F-5A/B Freedom Fighter, which first flew in 1959. After that, many fighter air-crafts have used it, some of which are mentioned after the qu...
I would think that a center fin with no “fillet” - like in a flush fin box - would be better but in the side fins - canted and toed in - maybe not.
I remember seeing, reading Jobson would hot coat on his canards. Reason he was a fan of fin boxes. Wanted the canard as clean as possible. I’ve never met Jobson,only heard stories from guys here and on the shapers. He used a formula to set his placement, fillets would be increasing the stall angle, probably a variable he was eliminating. The fillet would have been hard to control. Length/height leading into canard and aft. This is only a thought of mine.
I think if you could glass fins on without filets you’d be on to something. GG might have mentioned it?
One thing I do know is the design is awesome and the rabbit hole is deep , I don’t think there’s another topic here that dives into design like a Twinzer can.
@One-Off foot placement is important. Notice a big difference when my foot is properly positioned.
I think if you could glass fins on without filets you’d be on to something. GG might have mentioned it?
One thing I do know is the design is awesome and the rabbit hole is deep , I don’t think there’s another topic here that dives into design like a Twinzer can.
@One-Off foot placement is important. Notice a big difference when my foot is properly positioned.
I think the filletless glass on involved routing a slot and then glassing the fin in. The fin would need a tab.
Regarding foot position, Wil said that you want your foot over your cluster. I always had mine as far back as I could (pre-programmed from my thruster upbringing).
Now I remember GG talking about it on here. Rob Brown has done it on his instagram page.
Once fyour doors in correct place .
Watched a recent review on the Panda Shiitake where big Craig noted foot position being really forgiving.
ETA I’ve never surfed a twinzer but am definitely curious.
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Before I glas
I think I would try it with 3 lb eps insert. Might be tricky routing. 1/4 in hole 1” (?) deep at the proper cant.
I agree, up to a point. A bit easier to turn from a more slightly forward position. I set my fins back a ways from traditional, but Im kind of an old broke down power surfer and like that solid drive-y feel.
They definitely are easier to turn with foot placement forward like @need 4 speed said. I was referring to the magic of a proper placement of your back foot. They become a different animal for me.
ditto. Addictively so, I'll echo ghosty, over the fins and away we go
If you notice my intial review I mentioned that the twinzer was sensitive to foot placment. I wonder if that was just a length thing- being 6-5 compared to 6-1 (bonzer). Most likely just a prpblme with the archer.
All this might be moot, for me, because after several days in a row riding shortboards my low back was acting up again.
I'm always compromised. At my local reef I have to find the compromise between performance and competing with longboards. My most recent iteration- the 7-6 twinzer- leaves me scrounging for scraps on crowded days. So far 8-3 is the smallest I've gone and still felt somewhat competitive. My next iteration will be 7-11 (magic number??)
Now with shortboards, I think I have to find the shortest length that doesn't trigger my back. This will be even trickier. As it is a moving target as I inevitably get older.
All this might be moot, for me, because after several days in a row riding shortboards my low back was acting up again.
I'm always compromised. At my local reef I have to find the compromise between performance and competing with longboards. My most recent iteration- the 7-6 twinzer- leaves me scrounging for scraps on crowded days. So far 8-3 is the smallest I've gone and still felt somewhat competitive. My next iteration will be 7-11 (magic number??)
Now with shortboards, I think I have to find the shortest length that doesn't trigger my back. This will be even trickier. As it is a moving target as I inevitably get older.
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I hear you. Few days of swell I can barely put socks on. In water I still think in 18, take beatings I probably shouldn’t.If you notice my intial review I mentioned that the twinzer was sensitive to foot placment. I wonder if that was just a length thing- being 6-5 compared to 6-1 (bonzer). Most likely just a prpblme with the archer.
All this might be moot, for me, because after several days in a row riding shortboards my low back was acting up again.
I'm always compromised. At my local reef I have to find the compromise between performance and competing with longboards. My most recent iteration- the 7-6 twinzer- leaves me scrounging for scraps on crowded days. So far 8-3 is the smallest I've gone and still felt somewhat competitive. My next iteration will be 7-11 (magic number??)
Now with shortboards, I think I have to find the shortest length that doesn't trigger my back. This will be even trickier. As it is a moving target as I inevitably get older.
On next board you could always bump up the thickness along with a concave deck. Have a stretch and really enjoy it. Only time I notice it is sitting on it, few surfs and I can’t really tell, it’s what I’m planning on doing on my next one.
I no longer feel 18...but still maybe 40? I had surfed 4 days in a row and by the fourth I think my nervous system was rebelling. I'd go to pop up and my feet would be dragging. A couple times I'd inadvertently end up on my knees. "WTF?"
I was thinking I should do like Sharky advised- 3 sets of 5 pop ups every day, but I always wonder if that would just accelerate the disc degeneration?
You might want to see your doctor. If he tells you to rest, find another. I’ve been there with my arms, hands. Paddling would feel like being shocked. I started stretching and working on core to help stabilize my spine. You might have some bulging in a few disc? Few things I’ll ignore, spine issues I don’t. I want to be upright for as long as possible. Good luck.
You shaping the 7’11yet?
Well, for the time being I'm back on the bonzer bandwagon. We had some really fun shoulder high sand bar action today and I was super swooping around from section to section with flow and speed. So much fun. My stock must have been visible because when I got to the beach a couple of the of the Seal Team crew told me it looked like I was having a lot of fun.
Oh yeah, forgot to mention, the whole parking lot at my local beach was filled with filming crew. I was told they were filming "Seal Team." Only in LA.
Oh yeah, forgot to mention, the whole parking lot at my local beach was filled with filming crew. I was told they were filming "Seal Team." Only in LA.