My all time favorite is a 60's wonderbolt fin that used to come on weber performers. That ames fin looks kind of like a rounded off version of it. They used to put the fins way too far back most of the time back then and it made boards completely unsteerable. Put a fin far enough forward with that mail box flag shape (whether rounded off or not) it'll enable you to turn even a thirty pound hobie incredibly powerfully. I like the unrounded version better just because its bigger and so will let you turn harder even though I'll admit it's probably not as fast. Here's a half way made one I made out of aluminum for an old wave set box. You can see how I shifted the whole thing forward to make a hobie loose even though it's fin box is too far back.
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