A simple beginners guide to Longboard fins…
As you get more involved with your fin choice you will begin to agree/disagree with a lot of the following… it's meant as a 'primer' see how you get on, and remember there are no rules!
So, the question will arise sooner or later, 'what fin shall i get'
More often than not the question is prompted by the realisation that the cheap plastic wonder the board shop 'gave' you isn't really what the aspiring Joel Tudor should have on his board. First off let's ask the question what does a Fin actually 'do'? Might be easier to answer that by trying to ride your board without a fin in the box, good luck with that!. Failing that watch https://vimeo.com/114935352 carefully study what happens when you ride a board without fins. What you should immediately notice is how the board will slide around the face of the wave, almost at times falling out back'ass'wards, fine if you have infinite control like Mr Machado, but for mere mortals like you and I, not so awesome.
A fin, much like the tail on a plane, provides some lateral stability, just like a keel on a yacht it stops you slipping sideways. Unlike the Alaia, your back end won't break away and slide out behind you. Unlike a keel on a yacht, which is placed in the middle of the hull, a surfboard fin is placed at the rear of the board. That way you are able to control the front of your board to turn. The fin acts much like a pivot in this sense as well as a keel. As a general rule, move a fin forward to loosen things up and backwards to gain more stability.
So a fin will help keep you on the straight and narrow, but that is a very simplistic explanation obviously.
Your fin works in conjunction with the board it is bolted to, obvious really, but a fin that works on one board may not work quite so well on another. The complex relationship between the boards rails, bottom contours and the riders weight and style, the waves height, speed and profile will all affect the way a fin helps or hinders your riding.
To complicate matters further the position of the fin in the fin box will also change the way your fin works, there is often a 'sweet spot' when the fin works well for your board. A good rule of thumb is to measure about 8 and a half inches from the tail edge to trailing edge of the fin as a good start when positioning your fin, box and fin allowing, or place your fin in the centre of the box. A good shaper will place the box so you have good movement fore and aft. Start with that and then try moving the fin around and see how that affects the ride. You might even find a better position and not even need that new fin you think you want. A fin is after all the cheapest way to improve or destroy the performance of your board. An adjustable fin bolt is a God send when fiddling with fin position, we might even sell these, I can't remember…
So do you want to surf carving turns or be a more traditional nose rider?
What fin to buy?
Starting Out: Try something that looks like the above (classic Dolphin template), this will give you a good benchmark by which to judge others against, try to get something roughly the same length in inches as your board in feet. Good all-round fins tend to look like Dolphins fins, for good reason I guess. These fins will often have some flex, others will be stiffer, flex will give you snappier turns. They will generally have more 'flow' through turns. Check out the subtle differences in the shapes above, they all have a purpose. Steeper rakes, less or more area, different front and rear edges, fascinatingly variable. You may never need to evolve beyond these great shapes as they will be pretty good at most things.
A Dolphin fin will get you turning and give you snappy/drivey/flowing turns off the bottom. But if you are wanting to venturing into other domains try…
Nose Riding: What you want is something with more area in the tip of the fin. This will give you more hold and stability when you are on the nose. These fins are stiff and will have no flex. The downside is it will be harder to turn and you will have to pivot the board off the fin stepping back to turn. These are called Pivot/Keel fins and are generally suited to more traditional boards with squarer tails.
So a few observations… (pinch of salt and all that)
1. A fin of around the same length in inches as your board is a good starting point. i.e. a 9 inch fin for a 9 foot board. For tri-fin boards you can go that bit smaller, it's a balancing act between the relative sizes of your side bites and main fin.
2. Fin colour and fancy graphics make all the difference to performance… really, they do.
3. The bigger, or weirder shape of fin makes you not a better surfer, but however may attract more of the opposite sex, this is also true.
4. Flex, the big fin buzz word, get used to the feeling of your fin, try flexing the tip, some won't budge, others will be pretty springy, a flexible fin will be easier to turn, but you may prefer it stiffer when you get better or vice versa, decide if you can tell the difference and what you prefer.
5. Make a point of looking at what the best surfers at your break are riding board wise, see what fins they have, you can learn a lot like this, try to look at the whole package, height, weight, board, fin, don't stare too hard now.
6. Just like a sanded/matt bottom on a board a sanded fin will offer less water resistance, if you notice this difference, kudos. Seriously though all part of fine tuning.
7. One of the biggest fins you will see is on the back of a 747, check them out next time your jetting off to Indo, aero dynamics are very similar to fluid ones. Big fins for big guys, smaller ones for lighter folks, as a general rule.
8. Cavitation, a great word to bandy about when your discussing fins with your mates, look it up before you spout forth though, let me know what it's about though won't you.
9. The 8 and a half inch rule, position your fin in the box with it's trailing edge 8 and a half inches from tail edge as a good starting point for position, no sniggering.
10. A rub of candle wax will let you slide a tight fitting fin in the box more easily… some thin slivers of plastic milk bottle will slide down side of box to help minimise 'wobbly' in loose boxes.
11. Best to have a spare fin in your board bag, just in case you loose one, maybe forgetting to tighten up that adjustable bolt, shit DOES happen. In fact have two, order them now…