Optimal fin size depends on, not only the board dims and design (length, width, template, rail shape, rocker, bottom contours, fin placement), but rider weight, style of surfing (how the rider applies weight/pressure to the board), and wave size/water speed.
There are just too many variables for normal surfers to keep track of, which is how “magic boards” happen. And why shapers (Pavel, GG) who develop a system that limits the variables, and can adjust them for a particular rider/wave constant can have success recreating the magic.
…with a single fin if better to have a box if you are unsure. Also, I think that s better to move the fin or change the “type” than put bigger fin.
I deliver the 7 4 eggs with 7 1/2 fin in one type of template but different thickness and flex.
If the surfer is big powerful and crank the rails on the bottom turns, is better to use larger fin area on the sides for the multi finned boards; however, there s several variables here, like the rail curve (outline, rocker) type of wave, etc, so you should check all these aspects on the board or on the design you are about to shape to determine what type of fin.
But still think equal to the single finned board, better to have the possibility to move the fins or have the right dims than go larger and larger; and a very important fact is the back foot position, more if you do not have the chance to move fins; that s is very important more than the fin itself.
You can definitely have too much fin, especially if you are talking about the rear fins of a quad. I like bigger rear fins if finbox placement is towards the rail, and smaller rears if the placement is more towards the stringer (McKee-ish)
My favorite quad fin setup for a rail-finned board DOES NOT work on this new board I got that has quad rears closer to the stringer. It actually made the board feel like it was dragging and nearly stop a couple times. I could drive hard of the tail and make it go, but it was nowhere close to that fast, free quad feeling you get when the fin setup is right.
One note I would add to the discussion is that as the size of the wave (and hence speed of the board ) increases you can decrease the size of the fins (unless choppy conditions come into play).
I changed from my standard FCS PC-5 thrusters to a Kinetic Racing twinser setup on my Al Merrick 5’3 biscuit and found the board had more drive, more hold and still enabled me to throw the tail around. The only negative is when the fins come out of the water the board pivots faster, so I was over turning and sliding more until I got used to using a bit more finesse.
So, yeah more fin area was better for that board.ther must be a point where the surface area makes it too stable/tracks too much/lose of manoeverabiltiy
Single fin boards are more glide dependent to obtain max hull speed, best obtained with the minimum amount of effective fin area effectively placed. Try a couple of fins, move them around a bit, dialed in.
Multi fin shortboards are more turn dependent to generate speed, so work best with the maximum amount of effective fin area effectively placed. Lots of rocker, concaves, 3/4/5 fin set-ups, not so easy to dial in. Reason why most of us have a box, or two or three full of various fin sets sitting in the garage next to the quiver rack.
In my experience, surfing style has a lot to do with fin size. If more of a front foot surfer, driving the board more forward, a bigger fin is needed. If more of a rear foot surfer a smaller fin is adequate. Comes down to where leverage is applied.
I’ve found that on my 8’ round pin I definitely prefer my 9" Greenough stage 4a. I tried a 7.5" stage 4a and I had a few rides that I almost spun out. When I started riding my home made 8’ boards back about 2005, I was using a 9" cutaway and I liked that, but with the pulled in tails I prefer the stage 4a.
I also think it’s the shape of the fin, a 9" Brewer is too much fin for almost anything. With that shape 7.5" looks big. For quads, I think the distance of the fin from rail and the distance of the front and rears really makes a big difference. I always go with bigger fronts, but if the rears are closer to the rail, I use a bigger rear than if the rears are closer to the stringer. My current standard quads are 4" and 3.5", but I also have a set of Robin Mair fins and they are a little bigger, maybe 4.5" or 5" for the fronts. The Mair fins matched with his recommended fin placement work great.
Here’s shots of the 8’ round pin and the Mair fins.
It seems pretty simple to me in the context of the same board - once you get into changing board design and fins in combination the question becomes moot.
Fins in isolation:
Bigger = better hold in turns and when driving, slower, more stable - confident, solid, stiff
Smaller = looser quiciker faster less hold - less predictable, free
For me its a question of going as small as I can until it is slippery and spins out because generally the smaller fin feels best like it improves the board - faster and looser (until its too much). This (for me) is the same with thrusters, singles, and 2+1 - less is better until you are spinning out then take 1 step back.
What do you think about a 2+1 fin set up that has regular thruster fins for side bites? I bought a used 9’ high performance longboard a few weeks ago and it came with 6.5" center fin and medium size thruster fins for side fins. Do you think that is way too much fin? Or does it have some advantages? See the photo. I rode it like this once in tiny surf (1’-2’) and couldn’t really give it a fair trial.
I put on an 8" carbon fiber center fin, pushed all the way forward, and rode it as a single in 4-6’ surf and had lots of fun on it. Do you think if i put GL3 sidebites on it with the 8" center fin, it will be too much? I don’t have an extra 7" fin right now.
Someone else suggested that I try some small rear quad fins as side bites, but the only ones I have right now are foiled on both sides so that may not be ideal either. Anyone try that yet? It kind of makes sense with a smallish center fin for a 9’ longboard - if they were foiled with a flat surface on the inside, right?
I don’t like bigger sidebites on a 2+1 setup. Even the avid longboarder will have a “pivot-component” in his/her turn. Therefore you would like to have a centerfin bigger than the sidebites. If you would like to reduce this pivot-component and approach the “thruster-turn” I would suggest some more rake in the centerfin. Bigger sidebites tend to create drag in small surf and tend to lock during a bottomturn in bigger surf. IN other words; I like small sidebites!
A thruster setup on a longboard feels like a thruster too big. The only time I saw guys rip on thruster longboards are the smaller Peruvian guys on thin longboards and open face pointbreaks (Chicama, Huanchaco).
Here is the fin set up I’m going to try next - hopefully there will be waves tomorrow. It’s the same 8" carbon fiber fin that I rode as a single fin, plus the GL sidebites.
I was planning on using this longboard only on small days or at high tide (when the waves are fat and mushy) because I have short boards and other boards when it’s big and bigger - but this board was super fun in head high waves so I may reconsider it’s main purpose. I’d like to find a great all around fin set up, leaning towards the smaller days. I’m about 160 lbs and an intermediate surfer.
Bill - my BEST single fin I ever had was the 9" Brewer single fin (blue/black) . I also had a Greenough red clear flex fin on a phenomenal -William-Dennis 6’10"-7’2" egg. I thought it was 6’10"? It had some width though! The width 21"+ it sported a long flex fin -just like a tuna fish!it worked great in solid 3-4’ calif beach breaks, and I made every single wave till the end on my last time out on it…no bs. I couldn’t get enough of it…fyi it was the first board w convex bottom and pinched rails. Prob one of the best surfboards I ever owned! And it was given as a gift. Mind you, the board was sun baked yellow, and a “Pier pont rat” gave it to me! No bs.
The surf wasn’t as good today as it was when I rode it as a single fin, but it was good enough to decide that the 8" fin with side bites is a little too much fin for me. I think I’m better off with the 6.5" center fin with side bites so I’m going to try that out next.
Hey Bill, are you suggesting that the small quad rear fins are a good idea with the 6.5" fin? or just better than the thruster side fins (fcs M3)? And also because I already have them and am not ready to buy new fins yet?
BTW, I’m riding the 9’ Josh Mohr Model made by Bob Pearson at Pearson Arrow. Thanks again!
