Zero Cant & Toe Fins on a Sup

[PonoBill]

Standuped--Wow, that's a lotta toe in.

Hey, Beasho, the original bone of contention was that toe would create drag 100 percent of the time. I still don't agree to that for both fins. I do, however, agree that asymmetric foils will always provide lift and drag. I'm just not sure that it isn't something you want. I do think that most surfers want to turn as much as they want to go fast--maybe more. I think if I were trying to run away from the whtewater at Mavericks I would have a major league interest in speed, and turning would be something I saved for little days. But I'm not. In fact I'm often doing big cutbacks and otherwise hanging out waiting for the shoulder to catch back up, while watching the sections ahead.

That definition seems to be odd and incomplete. Maybe it works for fins since no one builds complex camber profiles into them.

[standuped]

What's interesting is that the SIC 2015 catalog has a model very similar to my JP Fusion and it has 5 straight fin boxes.  Looks like a sweet board.

[OUTSIDEWAVE]

BEASHO THIS IS FASCINATING!! I have  always been one to fool around with my fins doing some crazy stuff like  grinding  my  fin base on the turbo tunnel so I could ride it as a  big twin fin on my Old Ben apia long board. In the 70's I made keel  fins out of plywood, but they broke.  a lotHey wasn't even out of school yet ( i am  a geologist)..Never been satisfied with the status quo.  and as Learned more about boards and take to more shapers I came away with there are some that really understand concepts of flow well others that  have a good eye and a steady hand  but not many who have both and the vision  to do both  and push the limits.

Let me ask you what  do you ride right now as far as fins go?  do you shape your own board so you can set your fin boxes they way you want?  what do you recommend as a a set up?  I think that the Joe blair fins are  thin and  have equal foil on both sides.

if  you have boxes with toe in, is there a way to  change the toe angle? aside from removing the boxes?

[SUP Sports ®]

I played around with the Four Way Fin System on some boards that I designed and had Imagine build back in 2008 - 2009...
After all of the experimentation our team did, I ended up right back where I started from, as far as toe-in is concerned with my board designs...

I am after responsiveness and maneuverability on a wave riding board...my board and fin designs already incorporate speed elements inherently...
I'm not looking to go faster down the line in a straight line on a wave...single fins do a mighty good job of that...YMMV...;-)

From the Four Way Fin sight...

When to increase Toe-In:
Increasing the toe-in of the side fins (i.e.turning them in the direction of the stringer) will increase the boards responsiveness during turns. Remember that increasing toe-in, results in less water resistance during turns.

When to increase Toe-Out:
Increasing the toe-out of the side fins (i.e. turning them away from the centre stringer and towards the direction of the rails) will increase the boards speed particularly when driving down the line.

Adjusting Splay / Cant
Fin Splay refers to the angle the fins are placed relative to the underside of the surfboard, or the number of degrees the fin tip is offset from the fin base. Fins splayed outwards would result in the fin tip being more towards the rail of the board compared to the fin base.

The side fins should always be splayed at the same number of degrees, whereas the centre fin must remain at 90 degrees – no splay.

When to increase outwards splay:

Increasing the outer splay of the side fins (i.e. the tips are leaning more towards the rail of the board) will

increase the boards responsiveness during turns.

When to decrease outwards splay:

Decreasing the number of degrees the side fins are splayed from the rail (i.e. more towards the centre stringer of the board) will increase the boards speed particularly when driving down the line.

[standuped]

I just impulse bought  my first "short" board. This how the shop had the fins set.  should I move the symmetrical shortys to the front? Or am I SOL

How does it ride?

Tom, I made a little write up in gear review. Sorry to hear about your friend.

[nalu-sup]

I just discovered this old thread, and decided to reopen it for anyone who still has the interest and patience to read more on the subject. If you are tired of this topic, just laugh at us fin nerds and move on.
I am a fanatical fin experimenter on all my water craft; surfboards, windsurfers, waveskis, and SUPs. Though I play with the theories in my head, I am a long way from having a degree, so I must rely on a lot of experimenting. Here are a few things that I have learned from that approach, and since the results are all subjective, all of this may only be true for me.
1. I am very old school when it comes to boards in windsurfing, which is something that I still do for many hours every day when it gets too windy to wave SUP. All of my sailboards are now single fins, though my first four waveboards back in the 80s and 90s were all 2+1. Whenever I ride multi-fin boards now, I cannot resist looking down at the water streaming off the tail to see all of the turbulence created by the fins.
2. When I wavesail multi-fin boards, I usually feel like the fins are fighting each other over who will set the arc and who will stall. They can sometimes make some great turns on a wave, but I believe that the turns are less trustworthy because of the potential for one or more fins stalling. There was a great candid article on this topic in one of the Euopean windsurf magazines a year or two ago, where many of the top wave sailors at that time admitted that they found multi-fin boards less trustworthy in high speed bottom turns.
3. SUPS. This is my current field of experimentation, and I am still learning every day as I change my setups. Here are two of my current thoughts.
At normal surfing speeds, we do not get a chance to feel the extent of the drag created by toed in fins, especially if they are single foiled (more on this later). When I windsup, the drag from the thrusters becomes much more apparent as the speed increases, until it becomes the limiting factor that prevents the hull from achieving its speed potential. When wavesailing SUPs at speeds that are generally much greater than surfing speeds, I can sometimes feel the fins stalling during hard bottom turns, and the bigger the fin, the bigger the problem.
And now to why I reopened this thread which I just discovered. Way back on Dec 29th, Beasho made the argument for reversing the thrusters so that the flat side is out (sacrilege I know), and claimed that it worked better for him. I have actually been contemplating doing this, but for a different reason. Under normal conditions with the flat side of the fin at a pretty good angle of attack due to normal toe in, there is just no way at higher speeds that you are going to get attached laminar flow to make it around that sharp corner on the flat side, and so I believe that there must almost always be detached turbulence on that flat side of the fin if it is toed in and going fast. If the fin was switched around, so that the foiled side is now on the underside of the flow (on the stringer side), there is some chance that the water will be able to attach around the curved leading edge on the foiled side and achieve laminar flow. Since the flow is now being compressed against the upper flat side (now on the rail side), I am guessing that attached flow will not be a problem on that side even with moderate angles of attack. I think that Beasho also made the point that double foiled thrusters make the most sense, and I would agree. There is a lot of discussion about how the single foil creates lift, but if there is detached turbulence on the flat side, any foil becomes worthless. If you have ever experienced fin stall on a windsurfer at high speed, you quickly learn that a stalled fin is equivalent to having no fin at all. However, by just switching sides, I am keeping the experiment down to just one main variable instead of changing to fins with different foil profiles and stiffnesses.
So here is my current hypothesis for anyone to tear into. On wide tailed SUPs on smaller waves, it makes sense to run smaller thrusters (I am now experimenting with 3.5" GLs), either double foiled or flat side out in order to minimize the effects of the loss of laminar flow and stall created by toe in. The board does seem faster and looser.
As a side note, one reason this might be working for me is that the board I am experimenting on has four very deep hard edged channels back near the fins, that are providing a lot of drive and doing a lot of the work that thrusters would normally do. This might mean that I can get away with smaller thrusters and still get sufficient drive in the turns.

[magentawave]

I just read through this entire thread and my head is spinning. I tried a 2014 8-6 JP Surf recently with the no cant and no toe fin setup and it caught waves very quickly and was very fast on the wave, was drive-ee even when standing forward on the board, and it wasn't the least bit stiff. How the exact same board would have behaved with conventional cant and toe is anyone's guess. Someone mentioned that zero toe and zero cant on a simsup was too stiff so maybe it's not such a cut and dried answer in that the performance of a board with straight fins is dependent on other elements like the outline, rails, rocker, and/or bottom?? On the other hand, JP's Slate has the straight fin setup so I guess it works on them too. I dunno. I just go by feel and my next board will be a thruster with the outside fins set at zero cant and zero toe.