Skid Fin Angle or not to Angle?

[dcrummett]

I race kneeldown hydroplanes (outboard) with a typical picklefork design and a left sponson mounted skid fin (located just aft of the sponson). There are varying theories on a vertical vs. canted mount of this fin. Any discussion on this as to performance in a turn? I've run vertical fins for a number of years and know some people recommend up to 5 degrees inboard cant for the bottom of the fin?????

Dan

[tom28571]

I mounted the skid fin on my little runabout vertical, but then I don't blast around sharp turns on a race course. I would imagine that the inward cant on a fin mounted on the left side of the boat would generate down force to help hold the boat down in a hard turn. Pickleforks don't bank inward on turns so they may need some inward down force on hard turns to keep the boat from lifting and ventilating the fin.

The force on a skid fin is considerable.

On right hand turns the effect would be opposite and not so good as it would lift the boat out and cause more skid. On straightaways, there might be some steering to the left because of extra hull drag on that side.

[dcrummett]

Thanks! I know the unlimiteds used this method, and I now understand it does help the fin from deflecting as severely as it might in high-power turns.

The "new knife" went on at 5 degrees cant... will see how it runs this weekend during a two-day race.

Thanks!

Dan