Newbie here. Weed fin question. I understand the normal weed fin design moves the center of pressure back compared to a normal fin. If so, why not shape the fin in way that attempts to keep the center of pressure in the same spot as a normal fin? See diagram, not to scale, just to get the idea across.

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graygeezer said..
Newbie here. Weed fin question. I understand the normal weed fin design moves the center of pressure back compared to a normal fin. If so, why not shape the fin in way that attempts to keep the center of pressure in the same spot as a normal fin? See diagram, not to scale, just to get the idea across.

Many do :-
Tectonic Speed Demon
UFO Weed Forward
Tribal Delta Sym
Unifiber Lessacher Anti-Weed
Black Project Kestrel
etc.

You have drawn 3 different fins there too. Pointer weedspeed & delta. Range of use - no weed, some weed and thick weed in shallow flat water.

It's called offset and is exactly what many weed fins already have as per above.

The problem is mechanical, you can't shift a fin of any size forward enough, because it's attachment would be too weak.

Your example is very close to how a lot of us make our fins, that fin is short enough for the thickest part of the fin to still be in the box.

But I don't do it like that my boxes are set 10mm further forward in the board, because I always use shortish weedies.

If you have mild weed you can use a more upright fin with less rake, the denser the weed (or a shallow start) is, the more rake.

Sailing predominantly with weedies, it's just a case of shifting your mast base back further.

Tribal weed speeds are a pretty good compromise, but best suited for lighter weed spots due to less rake.

A fillet helps a little spreading the load, but even with 3D printed fins, I can put the box way aft with no structural failures...yet.

Is that a carbon rod I see, running from the tip to the middle of the box?