PDA

View Full Version : Futura 144 - Drake SL50R - Noisy!!


Pryderider
3rd April 2009, 11:30 PM
Hi out there!

Had yesterday the first chance to ride my new Futura 144 - fantastic board, high speed, easy going, but........a noisy fin!! Mounted the original Drake SL50R and every time the baord gets planing there is a high whistle-tone. Ugly...uuugh......Had this problem a few yaers ago with my old board/fin and could only solve it by mounting an additional fin (Lorch) whitch was more stiff. But thought, Drake/Deboichet Fins would be from that high qualitiy too!!?? Anybody having similar "fin-problems"??

Unregistered
7th April 2009, 08:12 AM
the only board i have ever read/heard doing that was the earlier BIC Technos - never heard about SB boards doing this !!

Unregistered
7th April 2009, 08:30 AM
found a hit on the web that says , yes, SB does have whistle on occasion - i am surprised !! but that was 2003 !!!

"I have Starboard 186X with fin 70 curtis. When board start sliding you
can hear horrible noise like whizz or whistle. I don't know how eliminate
this noise, is it problem with fin's resonance or with board."

Unregistered
7th April 2009, 08:33 AM
and another from 2006...

Roger Jackson has posted instructions on how to do this in other posts. I'll let his words speak to the 'how.'

http://www.star-board.com/forum/view...hread_id=21526

Quote:
Yes, you can take a sanding block and put a flat (better still a tiny radius) on the traling edge and tip of your formula fin without affecting the performance of the fin to a degree you will be able to tell.
We've been "blunting" the TE of fins that "whistle" for years with no affect on the performance.
Run the sanding block (with 240 or 320 grit abrasve paper) down the TE of the fin with the block perpendicular to the fore and aft axis of the fin. 2-4 passes down the fin will take the sharp edge off. Then turn your sanding block to a 45 deg. angle and "break" the sharp edge where the tiny flat meets the foil of the fin. Just once or twice down the fin and you will have a nice 45 deg. chamfer that won't cut you if you happen to rub your leg or arm against it.
__________________

Roger
7th April 2009, 11:54 AM
Hi Pryderider,
Yes, nearly all fin designs, from virtually all stock and custom manufacturers seem to suffer every once in a while from the annoying "whistle" vibration of the trailing edge.
It's easy to fix.
Only 2 causes that I know of:
#1 the trialing edge gets "thinned out" too much and it vibrates.
So, as suggested above, use a sanding block to slightly "blunt" the trailing edge pependicular to the fore and aft axis of the foil.
This will also dull the sharp edge a bit and make it less likely you will cut yourself on the back of the fin when waterstarting or beachstarting if your leg/ankle/foot happens to come in contact with the TE of the fin.
After you sand it a few strokes to blunt the edge, turn your sanding block to 45 deg and
run it down each side of the blunted edge to make a little chamfer on the resulting sharp edges. Go sail your fin. If it still hums or whistles, hit it with the sanding block a few more strokes.
#2 cause of hums and whistles is slight concave areas just in front of the trailing edge of the fin. These little "hollows" thin out the material just in front of the trailing edge.
You can detect these concave areas with a straight edge placed on the fin perpendicular to the vertical axis.
A good "straight edge" is a hardened and ground dowel pin. Roll it down the trailing edge on both sides to check for "hollows".
If you find hollows, take your sanding block and work the trailing edge hollows out, then blunt the TE as suggested above.
Nearly all fins (custom/stock....machined by CNC or molded) are hand finished so these little thinned out areas are almost to be expected.
The people who finish fins are caught between trying to get a true foil with a thin TE and avoiding making it too thin in spots.
As I said, easy to fix.
Hope this helps,
Then

Pryderider
9th April 2009, 11:32 PM
Hi out there,
hi Roger!

Thanx for your very helpful suggestions. Will be riding my Futura next week - after sanding the fin!! I myself hope the whisteling will stop!! But itīs true, I detected little hollows and kind of "irregularyties" in the frontside of the fin. But really didinīt know if sanding would help and if it would do any damage to the fin and the performance. Now, after your nice help, iīll do and see..............