SURF COACH: The Right Single Fin
Updated an Original Post from 3/18/18:
In the late 80's and early 90's I realized that I could make the closeout sections of longer period swell while riding a longboard. So in my 20's, when the tropical season arrived with its 12+ second pulses, I stopped grabbing my shortboard thrusters and started opting for a single-fin longboard. Floaters and cutbacks instead of closeout barrels... that was just better suited to my style. And since that time-frame, I've always had a single fin longboard in my quiver. I'm not going to say dudes enjoyed carpooling with me up coast, having to tie my canoe to the roof, but whatever. Riding longboards with one fin has opened my eyes to so many other larger/wider surf crafts, and I've been experimenting with them ever since.
So let's talk fins for these sliders. What's best? What's the conventional wisdom say? One thing that I've learned from riding single-fin surfboards over the years is to never count a particular fin out. There have been multiple times where I thought a fin would never work, and it totally did. Sometimes I figured this out by accident or weird circumstance. Other times I was just bored and wanted to try something different. (Want to really go scientific method? Try a fin club like Finatic... pay a membership fee and then swap 'em out at your leisure). UPDATE 3/29/22: FiNATIC fin club is no longer in business.
In the end, the reward of finding the right fin for your log or hybrid is worth the time it takes to figure out. For most single-fin crafts, the general rule is an inch of fin for every foot of board. But truthfully, this rule isn't always a reliable guide, and it can limit the opportunities for some fun slides. So what principles are in play here? In general terms, a bigger fin, with more surface area, will provide more hold and drive... while a smaller fin, with less surface area, will loosen things up a bit. Also, moving a fin to the back of the fin box can make a board feel like it has more hold... but there are some problems with doing that, because your rail and fin work together, and if a fin is moved too far back, the placement can hinder a smooth turn. Honestly, if you're using a traditional fin template, there's a really big window for finding the sweet spot in the box on any board 9 feet or bigger... so there's really no need to get all paranoid about it.
Before I talk traditional fins, I'll just say that you shouldn't dismiss the funky and weird looking fins. For example, I really like using undersized cutaway fins in my longboards, which are often used with side bites. Eh. They have good enough hold on their own at 7.5" or longer, but mostly I like the way a cutaway fin pivots and draws sharper lines. I also feel like I can glide into better spots on the wave with a cutaway because there is less drag. But on the contrary, I also enjoy the feel of a good flex fin, with traditional size, and a longer rake. I like the way a longer-tipped flex fin sort've slings you out of turns... so on those bigger days, on a point somewhere in the Northeast, I'd probably go more traditional flex fin. Right now, I rotate three types of fins through my high performance pin tail... a 9" Rainbow flex fin, a 9" FCS II Connect glass fin, and a 7" Kai Sallas glass fin. I had an 8" True Ames cutaway, but I broke it off on a Horseneck sandbar back in 2017 and have yet to replace it.
UPDATE: I've added a few new single fin boards to my quiver over the past couple of years... a 7'6 Vec Singlecut, a 9'0 Christenson Bonneville, and a 9'6 Christenson Bandito. And while I've experimented with nearly all of my usual favorite fins, I did purchase some newer ones that I really like in these boards. I use an 8" AU single fin in the Vec Singlecut, a 9'5" True Ames Yater Apocalypse in the Bonneville, and a 9" Christenson FCS II single fin in the Bandito. I've put the 9" flex fin in all of these with great results too!
Finding a single fin option for a shortboard, egg, or midsize is a bit more complex. I've sacrificed many sessions and spent many dollars trying various setups over the years. I am encouraged by FCS II's ability to change a fin position in the water, or change a fin completely without any tools. The only thing there is you can lose a fin in the ocean from time to time... so if the waves are bigger, use a fin that screws into the box. The FCS II system is convenient, but far from flawless. On more than one occasion I've knocked a fin loose while surfing. One time it happened in Costa Rica on a new thruster and I lost the fin. I was extra annoyed because I had just splurged on some expensive glass fins, and I had no replacements for the rest of my trip. There's also an environmental impact if fins are being lost and now rest on the bottom of the ocean floor. So just be careful using the FCS II click-in system, even on single fin logs.
At the moment I am using that same 9" RFC flex fin in my 6'4 winged pintail smurfboard made by Gee Rainbow. I've actually used a ton of different sizes and shapes in this board with a lot of success, but that long-tipped flex fin works like magic. I've had this blue board since the early 00's, and it's logged a lot of sessions. So it's been through quite a bit of experimenting. A smaller 7" performance style fin works well in there too, but it's sensitive to the location it's placed in the box. Smaller fins like to be placed in the center to the back of the box. But the bigger flex fin, set in the dead center, definitely turns that board on... so there's really no reason to switch it out. It's just a perfect marriage. My recommendation on finding the best spot in the box for your new fin is to start in the middle and adjust from there. Move it forward to free it up, move it back to lock it down.
What single fins are your favorite? Hope you're surfing where you are. Happy fin experimenting everyone!