Whistling fin with x186 and standard Curtis 70cm

That subject line should get Bill Kline's attention, right?

Bought a secondhand x186 yesterday, and got to try it out today. Northerly winds in the bay of Oslo, went out in a shorty (this summer has been the longest ever in Norwegian history) - winds ranging from lulls at 3 m/s to 14 m/s in the gusts. I rigged a Z1 8.7 m² and set the mast foot at 3/4 forward. When reaching I'd sometimes hear whistling from the fin. What would be the standard reasons for that?

Under the heads of the fin screws there is a metal washer and a disk of EVA foam. I suppose that's OK?

My previous board was an F2 XL that I had for a couple of years - now going downwind is scary again.

Christian,

We have had several long threads on this issue, so a search of the newsgroup on Google should provide lots of long answers

Short answer. There is probably a very small ridge on the trailing edge of the fin. A couple swipes with fine sandpaper will probably fix it.

Dense foam or rubber 'under' washers are typically used on these boards to spread the load of the fin washers and protect the surface.

Hope you had a good time.

Jack (Sarasota)

Hello Christian, 'Whistling 'of the fin is usually a trailing edge problem. Get a dowel pin or something else very straight or ground flat and check for a 'hollow' just ahead of the trailing edge. If there is one, take a sanding block and work it out flat. A simpler solution is to simply take the sanding block and run it vertically and at a right angle to the axis of the fin and 'broaden' the trailing edge slightly, then put a tiny 45 deg. angle down each of the sharp edges created when you moved the trailing edge forward slightly. There was a batch of fins at one of the big races last year that had this problem and this was the solution in all cases. Hope this helps,

oh yes, you got my attention.

Roger and Jack said it better than I can.

Anyway, we have improved the CR-15 and the new one may be the fastest production fin in 70 (most races are won on CUSTOM fins, production rigs and sails). The CR-15 has won two world titles and many other races worldwide. The CNC cut mold and prepreg construction make a nice difference in performance.

Bill Kline Gorge Sport USA Curtis Performance Fins, Orca Fins, Orca Kite Fins Hood River, OR USA www.gsport.com ph/541 387 2649 fax/541 386 1715