Dan:
Seems to be lots of advice from non-participants. As they say, free advice is worth its price and more.
For them that don't know, the official opti rule for runners is that there runners can be shorter than DN runners but not longer, and no thinner than 0.150 inches.
Also, the limited rules regarding the boat limit maximum hull/plank geometry, limit weight, require buoyancy, and require an optimist rig and sail plan (plus shrouds). This is a WIDE OPEN class, and anyone who can get a kid sailing is welcome.
Also, Stan Mercur sells optis with 26 inch 0.150 plates. They are the norm on these boats in Europe.
Now, despite my belief that 0.150 plates might be a good thing on the DN,
would be cheap and easy to build for an opti,
the fact is that I no longer have either the optis I built nor a kid interested in sailing them,
I, therefore, offer offer zero advice on how the class is regulated here in the US.
However I strongly suggest: Either stick to the international interpretations (wide open), or make an "official" US interpretation for regattas here and publish it.
But beware of "drift." It took almost 10 years of hard work to reunite the US and Europe in the DN after the drift developed. Others will want to define more hull restrictions, limit materials, add buoyancy tests, limit weight, regulate sail cloth, regulate rigging, etc etc etc. Good grief. Well intended drift.
Everyone who shows up should sail. Each participant should feel happy and enjoy the event. Each should come home with a talisman. (I sure want my souvenir from the NAs). Hopefully, some will graduate into DNs. Then they can argue and regulate that class.