Seriously. There are some large spade rudders here that look like they will have a lot of force put on them and none of them have shafts larger than 3" (compositions and structure unknown). 2-2.5" seems to be very common on these rudders, even though they are large and deep surface areas and on large boats.

I'm not sure what the CG has "taken notice" of in your posting, or your point in posting it. The boat in the picture is a Hinckley B40! The text simply states that one should inspect their steering system (as well as everything else). Nowhere does it mention spade rudders or undersized shafts. And the boats that required CG rescue in that regatta (which prompted that CG alert), did not have spade rudders (and none of them were catamarans)!

Mark