Sport Today

I would be grateful if you could answer a few questions concerning fins.

I got two fins with my board which I bought second hand.
One is 39cm long, 10cm wide max and nearly straight.
The other is 32cm,14cm wide max and is quite swept back.
My (only) sail is 6.0m (this did not come with the board).
My board is 298.

Do you need a particular fin for a given board/sail size ?
How do you work out what fin to use ?
How does the shape of the fin affect the performance ?

Also, one of my fins does not go all the way into the slot.
There is about 1 to 2mm of the base area proud of the board.
Will this cause a loss of performance ?

Thanks in advance

Steve Joures

The 32 cm fin sounds like a wave type fin. If it's planform is really
curved, then it's definitley a wave fin, but if it's got a lot of straight
surfaces, but they all angle toward the back, you may have a "swept pointer
of some sort. This fin will probably not go upwind as well, and at slow
speed will be fiarly easy to "spin out", but once you get some water
velocity on it it will hang in and not spin out very easily at all.
Use the vertical fin for fla***er, hi pointing, hi- speeds, and use the
swept fin for rougher conditions, smaller sails or if you want the board to
be looser, and turn better.
If these are stock fins, that came with the board, they can be quite good,
or not very good at all. You need to sail them and see how they work for
you, and then try some other fins that are larger/smaller and see which you
like best.

Yes, the fin root being "proud" of the fin box in not good at all. Perhaps
you have a "Euro" base fin and are trying to put it in a Chinook style
finbox. Check the two fin roots against each other. It one is about 1-1.5
cm longer across the vertical axis, then l'd guess you need to find someone
who knows the difference and have them advise you as to which fits your
board.
If you could tell us the brand of board, and the trade names on the fins
(if any) we can advise you a bit better.
Hope this helps!

Your other questions are good but I'll leave it to the other guys to
fill in the blanks (because I'm interested too).

~Jamie N

Oops., got all wound up and forgot about the other questions.

If the fin does not fit in completely in the slot, you should sand it down
until the board and fin fit perfectly (make sure to sand the same amount on
each side and underneath otherwise it will not be straight anymore and that
would be an even worse problem).

Francois

See http://www.sailusa.com/fins.html for more about fins.
More will be added next week.

Good Luck!

Brett USA-70

Come on Guys,
Everybody knows that in the Chinook type of fin boxes, there are 2 different
ones. The A, and the E. A for American, and E for Europian. The E box is deeper
and slightly thinner. Which was partly the reason for the Bic boards aluminum
fin boxes that almost all went soft. People were bying A box fins, fitting them
nice and very tight, and voila. Fin didn't go all the way down, so all the
pressure from the fin was on the lower (outside) end of the box and would
soften up in no time. Make you buy the right fin for your box. We repair boards
here all summer, and if this problem didn't exsist, we would not have repaired
half the fin boxes we did.
Bruno
2 Rad

Rule of thumb, use the biggest fin you can that doesn't cause the
board to rail up when the sail is powered (ful of wind).  When you
push on your feet and the board tends to lift on the windward side and
feels like it doesn't like to come down the fin is too big.

Postulate of fins: Bigger guy, bigger fin.

There is always an exception: If you don't need to point and or the
water is rough, smaller helps.

Bigger fins jump higher.

Two fins will get you by if your on a budget, a large straight up and
down pointer in the 11 inch to 15 inch catagory ( How big are you?)
Then a smaller more swept back fin in the seven to 10 inch catagory.
Determining factors on which side of the range is wind and weight. I
am two hundred pounds and use a 10 inch fin for my small fin. I can
get by with nine inch, but it just doesn't give me as much air when I
jump.

Limiting factor on the large fin is how strong is your fin box
relative to your size.

The posting about fins has been one of the most informative discussions I've
read.  Thanks for the helpful posts everyone.  Could a few of you please help
me with another fin question?

For shallow fla***er sailing in light winds, say 12-20 kts, like down at
Hatteras, one would normally sail a vertical race-style fin.  What if the fin
digs down into shallow sand bars?  I heard someone somewhere say that a weedfin
will avoid this.  Would you all suggest this type of fin or a more swept-back
fin like a Tru Ames Convert?  My 298 Veloce came with a 14.5" vertical fin and
I'm looking to buy a 2nd.  I'm 190 lbs., and sail an old 12'ft raceboard and my
new Veloce.  Thanks for your advise

Dan Thorne, Lorton, Va.

Depends on your objective.

A lower-aspect-ratio (stubbier) fin will keep the area needed to run big sails
and clear the sand better, but it'll be generally harder to jibe unless it's
swept back, and it'll be slower.

A weed fin is noticeably slower, but will clear the sand better, track well,
and turn well. Brushing the sandy bottom shouldn't hurt it.

A curved "wavy" fin will manuever and jibe much better than blades if you want
to start B&J sailing, but will be slower than a blade.

Or you can use shorter blades and rely on technique and a sensitive foot to
prevent spinout if you want to stick with straight-line slalom sailing.

Mike \m/
Never Leave Wind To Find Wind

Let me fix this! Man, I gotta learn to proofread better!

Dan,
   Every year I have a day in Hatteras when it's blowing 6.0 and I begin by
putting on a 14" blade fin.  It's great until I either start catching weeds or
 (depending on the wind direction) hit sand bars.  Every year I switch to a
swept pointer, which always seems to solve the weed problem (I've never needed
a weed fin), rides a little more shallow than the blade (missing some sand
bars) and on the few occassions the fin starts humming in the sand, I don't get
pitched.  

Maybe this is the year that I don't rig the blade in the morning!  ("You teach
best what you most need to learn":  Jonathan Livingston Seagull)

-Michael
US5613

A follow up question:

Do you think an old Mistral Malibu, European fin box could handle a
modern 40 - 50 cm fin?  I have a 34 on it now, and most folks tell me
it's too small.  The 34 is much better than the original a blue
plexlglass swept back fin with two or three ridges sticking off of it,
but if I don't get a new long board, I would plan on changing the fin.
I'm concerned that the fin box may not be strong enough to hold today's
bigger fins.