Fin size for 10'6 board??

Hi everyone,

I ought to start by saying MANY thanks to all commentators in this forum as I have learned enormously from your posts.

Here's my question: I have a Mistral Malibu 10'6 X 32, 193lt , single fin SUP. So far I used it for general touring but more recently I have started experimenting with sup-surfing (beach breaks in Greece). I recently acquired a 7-inch FSCII fin (type: 'connect') as it was recommended to me by the vendor for surfing. I am not qualified to comment on whether it is much better from my previous 9-inch fin in the surf, but I have a problem with it concerning getting to the waves (esp paddling upwind) as the board tends to rotate much more than before (hard to keep going straight).

My question is: have I gone too small? What would be the desirable size of a fin for catching waves on this board? My weight is 74kg and the board weighs around 10,5kg. I also have a second 10-inch fin for touring.

Thanks so much!
T

If it is difficult to keep the board going straight when flat paddling, it will be difficult for you to get the board lined up correctly to catch waves, especially if you are not that experienced.

Also, a small fin like that on a large board will probably result in the board slipping sideways when on a wave of any size.

I have lots and lots of different size fins that I've used on my 10'6" noserider. If surf is very small I sometimes use a narrow width 7.5" swept fin - it is difficult to keep the board going straight when flat paddling, somewhat difficult to get the board lined up for taking off - have to paddle more gently(also with the paddle more vertical) or the nose will turn, and, the fun part for me is the sliding more sideways down the wave (especially when on the nose) and "side slipping" during turns, rather than carving.

For the ultimate in control I use very wide width D fins that are from 8.5" to 10" tall. Of course they have more drag, but are the easiest to paddle straight and provide lots of stability because of the deep surface area. I think more surface area, more precision (hopefully the drag isn't too much).

I would think your 9" fin would be more suitable for surfing than your 7" fin.
Part of it depends on the shape.
More width and more depth will generally give you more stability
and make it easier to paddle straighter.

Sweep is another issue - I think swept fins provide a bit less stability for equal size because the surface
area is further back from where you are standing. So, if a fin is swept you might want it a bit larger for stability.
As for paddling straight, equal size, the more swept, the straighter you'll likely go. On the other hand, your
turns when surfing will be a bit more drawn out.

The general rule is one inch in height for each foot in length.
So, yeah, I think you went too small with a 7" single fin for a 10'6" pretty large volume board.
I would try your 9" fin - it is probably large enough unless it has a narrow width profile.

It looks to me like your 7" fin shape has a pretty small profile.
Even at 9" that particular shape isn't that large - not bad -
that is a shape I would use with some side bites
but you have only the center box.

I routinely use crazy glue to build up the bases of fins that are too narrow
(and a file to file down fins with bases that are too thick).
You just drop the crazy glue on one side and spread it out. You might have to do
several coats - even a full bottle. You could just place it on the ends - maybe an inch each.
Sometimes the middle is too narrow - you'll figure it out. Usually I spread it on the entire side.
One thing - it cures fastest if warm and sunny. On a cooler day, I place the
fin on a surface that gets hotter - like the moonroof (dark glass) of my van,
or a black piece of plastic, etc.

That one looks better as a single fin (than the other one).
Since your board is very large, you might want the 10" version but 9" is probably OK.
Still you might want one with a bit wider profile - but that one does have a nice wide base.
(if you need help with balance and/or for noseriding, this one, or similar, would be pretty good:
www.surffcs.com/products/fcs-ii-hatchet-pg-longboard-fin)

As for supergluing. It is very easy. You are just applying a very thin layer.
I don't use the thicker version - it doesn't seem to dry/harden as well - I use the one that is more like water
(in a small bottle rather than a tube).
As loose as your fin sounds, it will likely take several applications - maybe a whole bottle.
Each time, you let it harden (in the sun) and, then, see how it fits.
You will notice which areas need more width - so in the next application you apply more in that area.
The fin should fit tight and not wobble. If you were to make it too thick, you sand that area
down with sand paper or, I like to use a flat file. It is very easy to do and inexpensive.

Again, really great feedback. Thanks guys! Subber, great recommendation- I might go for that fin actually and will try the glue too (indeed much simpler than I thought). DJ: in what size do you have that fin and on what board? (is it the Nalu you mentioned?).